Behavior

Introduction

Fish behavior is often varied and complex within and between species. Sensory stimuli, cyclic influences, population density and structure, habitat quality, the availability and use of space, the potential for competition and coexistence, the need to avoid predators, foraging and diet, reproduction, and other factors all contribute towards the evolution of patterns of behavior and their use. Despite the great diversity of fish species, their wide patterns of geographical and spatial distribution, and their highly variable ecological requirements, there are a number of patterns of behavior common to all fishes, as well as unique adaptations that occur only in a few.

Sensory systems and behavior

The behavior of marine fishes is shaped by sensory information provided by any one of their senses, both singly and in combination. They use vision to detect prey, avoid predators, identify species, choose mates, communicate, engage in social and territorial interactions, select and use habitat, and navigate. Fishes use their inner ear to detect sounds made by conspecifics during communication, by approaching predators, or by other fishes as they feed. If the fish has a swim bladder, these sounds can be amplified. Low frequency sounds made by movement, including struggling, are detected by the lateral line. Fishes may communicate by rasping mouthparts, gill arches, or other organs, and amplifying the sounds with their swim bladders. Touch is important in prey detection, predator avoidance, social interactions, and courtship and spawning behavior. Olfaction (smell and taste) is important in many predators for the detection of prey. The barbels beneath the mouth of a goatfish are highly sensitive and allow this fish to taste, as well as feel, potential prey. The sense of taste also allows a fish to determine quickly where a prey item is palatable or toxic. Chemical cues are also utilized for navigation. For example, salmon utilize chemical cues to detect the natal stream, where they will return to reproduce and die. Some fishes, especially sharks, skates, and rays, and the electric freshwater fishes of the families Gymnotidae and Mormyridae, are capable of detecting minute electrical currents discharged by their prey. The patterns they detect allow them to pinpoint the location of the prey, even if lies buried under benthic sediments or is obscured by turbid or muddy water. Electroreception also allows some migrating fishes to determine their geographical position relative to Earth's magnetic field. Electricity is also used for communication in gymnotids, mormyrids, and some catfishes (Synodontidae and Ictaluridae).

Activity cycles

Fish behavior is influenced by various cycles that govern such activities as habitat use, feeding, migration, and reproduction. Circadian rhythms derived from internal or endogenous 24-hour clocks control hormone releases and subsequent behaviors. Changes in light levels on a daily or seasonal basis are a principle factor influencing rhythms. Lunar periods control tidal cycles that influence patterns of local migration, feeding, and reproduction. Seasonal shifts in water temperature or other climatic variables trigger migratory and reproductive behaviors.

Fishes and other organisms possess an internal, or endogenous, clock that is set to a period of approximately 24 hours for a given day. This clock can be adjusted daily by some sort of trigger or stimulus. Two common stimuli are the onset of daylight and the constant progression of low and high tides. The clock governs a number of basic behaviors, such as the onset of movement, feeding, or courtship, along with the hormonal activity that influences or triggers these behaviors.

Most freshwater and marine fishes are diurnal, or active in daylight, during a 24-hour period. As dusk approaches, diurnal species seek shelter in which to rest or sleep and are replaced by nocturnal species that are active during the night. At dawn, these fishes retire to shelter or simply rest until dusk approaches again. Some fishes ignore the changeover between day and night and are more or less active for 24 hours. The dawn and dusk changeover periods, also known as crepuscular periods, also trigger pronounced reproductive or predatory activities in a number of species. Vertical migrations, in which deep-dwelling species rise hundreds or even thousands of feet in the water column at night, only to descend when daylight approaches, are also triggered during these times.

Tidal shifts, either the onset of low tide or high tide, and the corresponding movement of water off or onto a flat, tide pool, or other type of habitat, govern the movements of fishes within or between affected habitats. For example, as the tide falls in a tide pool, residents must move out of the pool and seek shelter elsewhere to avoid desiccation or thermal shock. As the tide returns, so do the fishes. Similarly, predators cue on the outgoing tide and move to locations where prey will gather or pass through as they move out of an affected habitat. Tidal shifts also trigger courtship and spawning behaviors that favor the movement of pelagic eggs and larvae off the reef or flat to avoid benthic predators or, alternately, to allow pelagic larvae to move back onto the reef or flat for settlement.

Temperate marine and freshwater fishes often spawn on a seasonal basis, usually during spring or summer, although others spawn in the autumn prior to the onset of winter. Spawning in spring or summer provides an opportunity for larvae to feed and grow before the falling temperatures of autumn and winter slow growth and activity rates. Fishes spawning in the autumn have eggs that may overwinter and hatch with the onset of spring. Spawning in river species is often timed to coincide with annual or seasonal flood cycles that trigger migrations, but that also provide feeding opportunities for juveniles and adults and the increased dispersal of young.

Tropical, and some temperate, species court and spawn in relation to phases of the moon. Some species are semilunar, in that they spawn every other week in relation to the new and full moon. Others are lunar, in that they spawn just once a month, either on the new or full moon. The actual day of spawning relative to moon phase may be variable, as a number of species spawn on the days on either side of the new or full moon, but reach a peak at a the height of the phase. Semilunar and lunar spawning may also be seasonal. For example, a number of groupers (Serranidae) form spawning aggregations once or twice a year, with the time of formation centered around a specific phase of the moon.

Many reef fishes, particularly those tropical species resident at low latitudes, court and spawn daily. Their reproductive cycle is regulated by daily shifts in light. Some species spawn at dawn, others at dusk or into the night, and still others during daylight, but the time of spawning shifts daily in relation to tidal phase.

Migratory behavior of marine and freshwater fishes may be controlled by annual, seasonal, lunar, or daily cycles that trigger movement from one location or depth to another. Pelagic fishes, such as marlins (Istiophoridae) or dolphinfishes (Coryphaenidae), migrate great distances annually. These species, and numerous others, track changes in water temperature and move from winter to summer grounds, or vice versa, for feeding and reproduction. Many river species, especially in larger rivers prone to flooding, migrate annually or seasonally to take advantage of the new spawning habitats and food sources made available when bottomlands are flooded. Fishes may migrate from one body of water to another for reproduction, and their progeny often migrate back from where their parents came. Diadromous, catadromous, and amphidromous migrations and subsequent recruitment of young may be triggered by annual or seasonal stimuli. Vertical migrations allow fishes to track the movements of potential prey as they migrate up and down in the water column.

Communication

Communication is an important component of fish behavior. The transmission and reception of information by a number of means facilitates social interaction, the partitioning of space, cooperative feeding, predation avoidance, and reproduction. Visual communication is important in all but the darkest or most turbid environments. Many freshwater and marine species possess color patterns that are helpful for species recognition, sex recognition, age determination, and for assessments of agonistic and reproductive states. Both black and white coloration and bright colors are utilized. Coral reef fishes, for example, are famous for their bright color patterns, or poster coloration. (Poster coloration, a term coined by Nobel laureate Konrad Lorenz, refers to the conspicuousness and potential advertising or function of bright color patterns in coral reef fishes. Such coloration is useful in intra- and interspecific communication during territorial interactions, aggregation formation and maintenance, or mating, and facilitates species recognition.) Color patterns may be permanent or temporary. The latter is under hormonal control in relation to the expression of certain behaviors. For example, some groupers assume temporary color patterns during social interactions. The detection of bioluminescent signals at night or in low-light habitats is another component of vision-based communication. Numerous deep-sea and deep-slope fishes utilize light flashes to communicate with conspecifics. Fishes also employ body and fin displays to communicate intentions during territorial encounters, courtship, and predation avoidance.

Several species of fishes communicate with sound. Sound production is used to warn predators, warn of predators, attract mates, attract conspecifics in school formation and maintenance, and to communicate intentions during agonistic, reproductive, and parental care interactions. Sound production also places fishes at risk from predation, as some predators have learned to locate sound producers and prey upon them.

Fishes produce chemical secretions known as pheromones, which may be detected by taste or smell. Chemoreception is significant for the recognition of conspecifics in catfishes (Ictaluridae), minnows (Cyprinidae), and other species. This recognition is important in establishing and maintaining social relationships, such as dominance hierarchies or territorial interactions. Parents and young in species that practice parental care of fry and juveniles, such as the cichlids (Cichlidae), employ chemical reception to identify each other.

Fishes make use of touch when communicating intentions during aggressive behavior, courtship behavior, and parental care. Electric communication in gymnotids, mormyrids, and some catfishes (Mochokidae and Ictaluridae) is also used for aggressive and courtship behaviors, and is especially helpful in waters where visual detection is greatly reduced or nonexistent. Electrical discharges made by these fishes are species specific. Variations in production properties, such as pulse length, interpulse length, frequency, and amplitude, allow these fishes to communicate or assess information about species identity, individual identity, sex, size, reproductive readiness, and level of agonistic behavior. The fishes also obtain information on the location of and distance between communicators in this way.

Behavior and habitat use

How fishes select and make use of habitat is determined by their behavior. In marine systems, especially coral and rocky reefs, pelagic larvae actively swim shoreward as they prepare to settle into a habitat. Prior to and during settlement they assess the suitability of that habitat. For example, damselfish (Pomacentridae) larvae settling onto a portion of a reef have been observed to reject this habitat, swim back up into the water column, and search for more suitable one. Post-larvae, juveniles, and adults all utilize a variety of patterns that allow them to compete or coexist with others already using a habitat. Agonistic behavioral displays are common. Sometimes, the behaviors involved are cryptic, in that fishes "sneak" into the habitat and become established without drawing attention to themselves. Size-structured schooling species likely join the school as larvae and exploit a repertoire of innate patterns that allow them to function cohesively with conspecifics. In shoals or mixed-species schools, members use a similar repertoire to join, maintain, or leave the aggregation. Solitary pelagic species employ a repertoire of behavioral patterns that allows them to swim, feed, and avoid predation in a habitat that provides little or no cover. If cover is present in the form of drifting pelagic algae, logs, or other flotsam or jetsam, small pelagic species seek shelter there. Some species, such as the sargassumfishes (Antennariidae), are adapted to life in floating sargassum, where they shelter from predators, ambush prey, and mate. Other fishes, such as juvenile butterfishes (Stromateidae), shelter within the tentacles of pelagic jellyfishes. Many small pelagic fishes recruit to floating structures, and larger predators are attracted in turn.

Benthic freshwater and marine species often adapt to specific conditions and make use of seemingly novel structures that provide shelter, feeding sites, or places for reproduction. In moderate or fast-moving streams, trouts and charrs learn to make use of rocks, logs, holes, undercut banks, and other forms of structure as shelter. Their swimming behaviors allow them to move up into the current, feed or chase off intruders, and return to their shelter sites. Sand-dwelling darters (Ammocrypta; Percidae) in slower moving streams rest on the sand, but bury into it to avoid predators. On coral reefs, various species use specific behaviors to burrow into sand, rubble, cobble, or mud in order to avoid predation, ambush prey, or rest. Fishes that employ burrows use those dug by other organisms or dig and maintain their own structures, often building multiple entrances or exits. They swim, hover, or rest near these burrows as they feed or engage in social interactions, but will dart quickly into an entrance if threatened. If resting inside a burrow, they may quickly escape via an alternate route if a predator is blocking or has entered one of the entrance points. These burrows are sometimes shared by more than one fish species or by invertebrates, such as snapping shrimps, in a symbiotic relationship. Other benthic fish use abandoned tubes made by polychaete worms or other invertebrates. These fishes swim out of these tubes to feed or mate, but return and move backward into them if threatened. Some tube-dwelling species use these structures as cryptic ambush sites from which they attack passing fishes. Shrublike corals, sea fans, and black corals all provide structures for a number of small reef species. These structures are shared because intra- and interspecific behavioral interactions define the use of space and reinforce order and structure within the coral head.

Social behavior

Agonistic behavior is employed by fishes to establish social dominance, defend territories, and ward off potential predators, and involves the use of displays given at increasing levels of intensity. The displays are fixed or modal action patterns, and the sequence of their use is often highly ritualized. The information communicated by a pattern or series of patterns in sequence is therefore recognized in the context of its use, and aggressive behavior leading to the injury of one or more parties in the interaction is often averted.

Dominance of one or more individuals by the agonistic behavior towards another of the same species occurs among groups of individuals, in shoals, and in schools. Dominance is expressed in either of two ways. First, a single individual may dominate all others who hold equal rank under the dominant fish. More commonly, a dominance hierarchy forms linearly, with a single alpha individual dominating others. The alpha is followed by a beta individual that dominates the remaining individuals, and so on. Dominance hierarchies such a this are often ordered on the basis of body size, with larger fishes dominating smaller fishes. They may also be ordered by different levels of aggressive behavior between individuals, with the more aggressive fishes dominating less aggressive fishes. Mating groups of sex-changing fishes also have hierarchies. For example, the mating group of the hawkfish Cirrhitichthys falco (Cirrhitidae) consists of a single dominant male, a large dominant female, and two or more subdominant females of variable size, which dominate one another on the basis of greater body size.

Agonistic behavior is used to defend living space, food resources, or mating groups and sites. This is known as territorial behavior. Territorial displays include the use of body displays, erect fins, color changes, sound production, chasing, or a combination of patterns. Defense may be against both intra- and interspecific intruders. The latter include competitors for food and space, but may also include potential predators of a defender's nest of eggs or free-swimming offspring. Territories usually consist of an area of relatively fixed size. The size of a territory varies within species and between species, usually as a function of size or sex, but will also vary in relation to the give and take of interactions with neighbors. A territory will often be nested in a much larger home range that is utilized by the fish or a group of fishes. Only that space that is actively defended by an individual is considered a territory. Territories may be permanent or temporary. For example, territories needed for courtship and spawning of a number of fishes are formed only during the breeding season or at certain times during the breeding season. Agonistic behavior increases during these times, but will often be absent during nonmating periods. Fishes may leave their home ranges or territories to form temporary multimale territories at courtship sites, known as leks, at which to attract females for mating. Some of these leks are "floating," in that their position may change relative to the location of females in the area. Territories required for feeding may be quite large, especially for larger predatory fishes, and may often greatly exceed the area defended for shelter space. Permanent territories often involve the defense of a shelter site. Males in single-male, multifemale, mating groups will defend their territories and those of the females contained within. Females, in turn, defend their smaller territories from intrusions by neighboring females within the same group. Mating sites of these fishes are defended in the same way. At the extreme end of territorial behavior is the defense of personal space, as seen in shoaling or schooling fishes that display to, or ward off, neighboring fishes who swim too close.

Territorial defense is also practiced by monogamous pairs of fishes. The best-known examples are the butterflyfishes (Chaetodontidae) on coral reefs. Pairs of butterflyfishes patrol

a territory and may encounter potential competitors for food or space. These competitors include conspecifics (also usually in pairs), as well as other species that may utilize the same resources. Defense involves an exchange of ritualistic displays culminating in the departure of the combatants. Highly territorial butterflyfishes, not usually in pairs, chase intruding competitors away; however, noncompetitive species are usually ignored. Clustering behavior, in which one or more individuals within a group, or mosaic, of territories rises up into the water column to assess others in the mosaic without engaging in agonistic interactions, is an interesting offshoot of territorial behavior, and has been observed in damselfishes.

Fishes form shoals or schools for protection from potential predators, foraging, overcoming the territorial defenses of individuals migration, and reproduction. Shoals are unorganized aggregations and may often be temporary in nature. They may consist of different species with a changing membership (heterospecific shoal), are relatively unstable, and may be dissolved and reformed quickly. Schools are organized or polarized aggregations that form permanently or temporarily. Generally, they are monospecific (contain only one species),

and membership is often age specific. Schools may dissolve at night for diurnal species, during daylight for nocturnally active species, or remain constant over a 24-hour period. Some schools dissolve under heavy attacks from predators, but reform afterward if sufficient numbers of fishes survive. The movements of schools are governed by a unique set of behaviors that determines position, synchronized movements, swimming speed, evasion, and flight.

Fishes have been found to be capable of transmitting traditional information socially. For example, certain benthic reef fishes follow predictable long-term routes between feeding and sheltering grounds as either darkness or dawn approaches. Experimental manipulations of the composition of a shoal of these fishes have shown that resident fishes can transfer information about the location of resting shelters to fishes new to the shoal during a dusk or dawn migration.

Fishes form symbiotic relationships with other fishes, or with invertebrates that share some common form of micro-habitat, food, or need. An excellent example of shared microhabitat is seen in the anenomefishes (Pomacentridae) and the burrowing shrimp gobies (Gobiidae). Anenomefishes live in close association with anenomes, flowerlike benthic invertebrates related to corals that have poisonous nematocycts in their tentacles and are capable of inflicting an injurious or deadly sting. The function of these nematocysts is to deter predators and immobilize prey. Anenomefishes have developed defenses against the effects of the sting and make use of the tentacles for shelter and nest sites. Part of the anenomefish's defense is behavioral, in that its undulating movements within the tentacles communicate to the anemone that it is neither a threat nor some form of prey to be stung and ingested. In exchange, the anemonefish defends the anenome against potential predators, such as butterflyfishes, that feed upon the anemone's tentacles. Anenomefishes may also "groom" the anenome by removing foreign matter and feces, as well as consuming potential parasites. Shrimp gobies share burrows with one or more species of snapping shrimps of the family Alpheidae. The shrimp, which is usually blind, constructs a burrow that may be shared with one or two individuals of a given species. The goby, or pair of gobies, guards the burrow at its entrance while the shrimp maintains it. If danger approaches, the shrimp is alerted as the goby or gobies signal it with flicks of the caudal fin. If the threat continues, the goby or gobies will dive headfirst into the burrow and the shrimp will retreat. Often there is species specificity between shrimps and gobies, and there is some evidence that both the goby and the shrimp settle out of the plankton together as post-larvae, prior to the construction of their shared burrow. The behavior exhibited by the anenomefishes and anenomes, and the shrimp gobies and the burrowing shrimps, is known as a mutualistic symbiosis, in that parties benefit from the relationship. Other examples of mutualistic behavior relating to cleaning and the control of parasites, and commensalistic behavior, such as the relationship between remoras and large pelagic fishes, are discussed in the section on feeding behavior.

Reproductive behavior

Behavior is an essential component in the reproduction of fishes, and is essential for the identification of conspecifics, the attraction and selection of mates, the process of courtship and spawning, and, in a number of fishes, parental care. To perform these functions, fishes have developed a repertoire of behavioral patterns. These are often used in conjunction with some physical trait, such as a larger body size, elongated fin rays, larger hook-shaped lower jaws (kypes), well-developed humps on the forehead, and unique color patterns (temporary or permanent). These physical traits are coupled with one or more behavior patterns, whose use and intensity of use accentuate the traits. The products of sexual selection, these patterns and traits confer reproductive advantages to individuals in a given species population. Other patterns are essential for the physical act of spawning or breeding to occur, or for parental care to be successful.

Fishes identify conspecifics as potential mates by the recognition of species-specific morphological shape and form, color patterns, scents, or various behaviors. This recognition is not as easy as it seems because of variation in each as a function of sexual dimorphism or individual variation. Sometimes "mistakes" in species identification are made, and interspecific mating occurs. Most of these mating attempts likely fail, but occasionally functional offspring, or hybrids, result. Once species identity is recognized, the next step is to determine if the potential mate is of the opposite sex. Again, differences in morphology and color pattern or other factors accentuated by sexual dimorphism are recognized. If no such differences exist, then the use of behavioral patterns becomes an essential tool for the recognition of sex. Once sex is recognized, potential mates have to determine if they are attractive or suitable for one another and if they are ready to mate. Sexually selected traits and patterns are utilized to determine this. In many mating systems, females select mates. Females are attracted to males that appear stronger, fitter, and capable of providing the greatest investment for her offspring. Males utilize a series of behavioral patterns to convey this impression. They may also emphasize the quality of their resources, such as feeding or sheltering territories, nest sites and qualities, or spawning site locations. Females assess these attributes and select the most attractive male or males, accordingly. Males, for their part, may wish to mate with the largest female or the most females possible. Larger females tend to be more fecund, thus increasing a male's opportunity to fertilize more eggs, pass down his genes, and achieve greater fitness. Mating with more than one female also increases fitness. Males compete with other males for access to females. The quality of their behavioral and physical traits and their use in intermale interactions, convey an advantage to one male over another.

Courtship patterns are used to attract mates, assess spawning readiness, and facilitate spawning or mating. A male employs a series of patterns to attract passing females or initiate courtship with females that form part of his mating group, and courtship bouts ensue with variable success. For example, in single male, multifemale mating groups (called "harems" by some authors), a male courts and spawns with each of his females in succession. Unfortunately for the male, this is not always easy. Individual variation in readiness to spawn among females means that a male may have to make repeated visits to females within his group before spawning takes place, and there is no guarantee that he will be successful in spawning with all females during a given spawning period. Sometimes the male is so busy attempting to spawn with one female that too much time passes and the "spawning opportunity window" closes before he can mate with others in his group. Alternatively, especially at dusk when light levels are falling, the male may become the target of a predator as he moves between females to court. Predator avoidance is costly because spawning opportunities may be lost. Worse, from the male's perspective, is that he might become lost, and control of the mating group will pass to a sex-changing female within his group or to another male from outside the group. Females are also at risk while waiting to court and spawn, and this threat may affect spawning readiness.

If courtship is successful and the male is able induce the female to spawn or mate, another series of patterns comes into play, which help the pair (or group, if spawning is in an aggregation) synchronize their activities so that the spawning or mating event is successful. Some of these patterns are as gentle as a male nuzzling the female's abdomen during a paired pelagic ascent, as in some of the marine angelfishes (Pomacanthidae). Other patterns, such as a sharp-toothed male shark grabbing a female's flank so that he can insert his clasper inside her and attempt internal fertilization of her eggs, are more forceful.

Modes of reproduction classify how fishes reproduce physically. The mode itself is not specific to a single taxonomic group, but may be shared by many taxa regardless of their phylogenetic affiliation. Criteria are defined based upon the degree of parental care, if any, invested. Thus, fishes may fall into three general guild categories: those that do not guard offspring, those that guard offspring, or those that bear offspring. Nonguarding species spawn openly upon substrates, either pelagically or benthically, or they hide their broods. Open pelagic spawning occurs in the water column. Fishes swimming in the water column engage in courtship and release eggs. Benthic fishes swim upward into the water column and release eggs and sperm at the apex of the spawning rise or rush. Spawning may be paired or in groups. Open benthic spawning includes the release of eggs onto the substrate (rocks, cobble, etc.), with the resultant larvae being either pelagic or benthic. Benthic spawning may also occur on plants as an obligatory or nonobligatory function, or on sand. Brood hiders deposit their eggs on the bottom, in caves, on or in invertebrates (such as corals, bivalve mollusks, and crinoids), or on beaches during a tidal cycle. They may also deposit eggs on a substrate that is prone to annual desiccation, in which case the eggs are adapted to resist this and hatch out when wet conditions return.

Spawning aggregations are a specialized behavior, and are formed by migrations of fishes to specific sites for courtship and spawning. There are two general types of spawning aggregations: resident and transient. Resident aggregations occur locally, in that members of the aggregation are drawn from the general area in which the aggregation forms. These aggregations usually form on a daily, semilunar, or lunar frequency. Transient aggregations consist of fishes that are drawn from a much larger area and population. Some species of groupers, for instance, migrate hundreds of miles along coastal waters in the Gulf of Mexico and Caribbean, and the number of individuals forming the aggregations can be in the hundreds or even thousands. These aggregations usually form annually or seasonally in relation to the lunar period. Both kinds of aggregations form at sites that appear to facilitate mating and the dispersal of eggs and larvae.

Guarders include those fishes that choose the substrate they spawn upon with subsequent guarding of the offspring. The substrates chosen include rocks, plants, terrestrial structures (such as overhanging leaves or flooded grasses), or the water column. Nest spawners construct simple or complex nests to attract females, deposit eggs, and provide parental care. Nests are made from a variety of materials, including gravel and rock, sand, holes, plant materials (with or without a "glue" secreted by the male), anenomes, or bubbles. In the latter case, males of some species make the nest by blowing bubbles of air and mucous onto an object or even the underside of the surface of the water. Miscellaneous materials are also utilized in nest construction. Generally speaking, nest construction is more common in freshwater than in marine species.

Fishes that bear young are either external or internal bearers. External bearers include mouth brooders, pouch brooders, gill chamber brooders, forehead brooders, skin brooders, or brooders that transfer offspring between one individual and another. Fertilization may be external or internal depending upon the taxon. Internal bearers have internal fertilization. Oviparous fishes deposit egg cases on the substrate; these eggs hatch externally. Ovoviviparous fishes retain fertilized eggs until they hatch and then release offspring "live." Viviparous fishes retain fertilized eggs that, as embryos, develop internally and are also released live. There are two forms of this strategy. The first is yolk-sac viviparity, in which the egg's yolk sac is attached to the digestive system of the developing embryo. The second is placental viviparity, in which a placental connection between the mother and the developing embryo occurs. Not all internally fertilizing fishes have internal bearing, however. For example, glandulocaudine characins (family Characidae) and many catfishes of the family Auchenipteridae have internal fertilization but are egg scatters. Similarly, members of the genus Campellolebias (family Rivulidae) have internal fertilization but are egg hiders.

One specialized form of live bearing is parthenogenesis, in which young are produced by a female without the fertilization of eggs by males. There are two forms, gynogenesis and hybridogenesis. In gynogenesis, an egg is activated following mating with a male of another species, but no fertilization of that egg occurs. The egg develops within its mother and is born as a female identical to the mother. In hybridogenesis, mating with a male of another species also occurs, but the egg is fertilized. The male's genetic component is discarded and the egg develops into a female identical to the mother.

Fishes select sites for reproduction in a variety of ways. For instance, salmons, trouts, and charrs make short or long-distance migrations to spawning habitat. Spawning occurs in gravel beds or other suitable substrates and includes the preparation of a redd, a depression made into the substrate where eggs are deposited, fertilized, and buried. In other fishes, nest sites may be placed within the territory of a male (or less commonly, a female) and are defended after spawning takes place between the nest owner and one or more mates. Nest sites may also be located within a home range of a temporary or permanent pair of fishes. There the eggs are deposited and fertilized, after which the site is abandoned. In some species, there is no nest at all, and eggs are merely broadcast over a suitable substrate. Spawning sites of pelagic species follow similar rules. Sites may be within a territory or cluster of territories, and are defended against intruders (usually same-sex rivals). Sites may also be used on a regular basis, due to some physical feature that may favor pelagic spawning, but are not defended.

Parental care of eggs and offspring is most often practiced by males than females, and is more commonly seen in freshwater rather than marine species. In some species of African cichlids, such as members of the genus Lamprologus, care is provided by helpers that are usually related to the parents and offspring. These helpers forego the opportunity to breed at this time, but manage to realize some sort of evolutionary fitness by learning parenting behaviors and by protecting offspring that carry a fraction of their own genes.

Care behaviors provide defense and maintenance of offspring. Parents protect the eggs and larvae in their mouths, brood pouches, or other structures, but also attack intruders that attempt to prey upon them. Defense also includes herding or shielding larvae or post-larvae from attacks. Maintenance behaviors include blowing on eggs to provide them with oxygen and to remove detritus or other undesirable objects (including dead eggs). Parents also provide alternative food sources for growing larvae. For example, some cichlids secrete a skin mucous that provides nutrition for their young, who ingest this by "glancing off" the flanks of their parents where the mucous is deposited. Intertidal species may wrap their bodies around an egg mass to shield it from desiccation during low tide. A freshwater tetra, Copella sp. (Lebiasinidae) from South America, lays its eggs on the leaves of overhanging terrestrial plants to avoid predation, and splashes water on the egg mass to provide it with oxygen and to prevent desiccation. Electric eels and some bagrid catfishes produce infertile trophic eggs to feed their free-swimming young.

A number of fishes practice alternative mating tactics that exploit certain behaviors to a strategic advantage. For example, in mating systems with paired spawning, the pair consists of a dominant or parental male and a female. Other, smaller, males in the vicinity, known as satellite males, mimic females both in color and behavior. The satellite males approach a mating pair and, if successful at "fooling" the male, will not be chased off. Then the intruder inserts itself into the dominant male-female courtship bout and attempts to fertilize at least some of the female's eggs. In other cases, smaller "sneaker" males use stealth to approach a mating pair, then quickly streak or dart into the pair's spawning bout as eggs are released to fertilize a portion of them. Among nesting fishes, both tactics have been observed in the bluegill sunfish (Lepomis macrochirus; Centrarchidae), whereas the latter has been seen in salmons.

In pelagic spawning fishes, smaller satellite males will streak into the water column to join a pair during their spawning ascent and fertilize part of the female's eggs. This has been observed in a number of groups, and variations on the theme occur. Two independent teams of researchers studying the reproductive behavior of the "haremic" Japanese sandperch (Parapercis snyderi; Pinguipedidae), observed repeated sneaking behavior by dominant males from neighboring mating groups instead of by satellite males. One team found that these males sneak fertilizations in neighboring groups after spawning with all the females in their own groups had been completed for the night. The other research group also observed this pattern, but found that dominant males temporarily abandoned courtship with their own females and carried out "sneak" fertilizations in a neighboring group in close proximity to their own location, when the opportunity presented itself. Males also spent considerable amounts of time and effort defending their groups from sneaking neighbors. The downside of these behaviors was that the opportunity to mate with their own females was lost and the females mated with other males while their males were busy.

Lizardfishes (Synodus dermatogenys; Synodontidae) have two strategies that depend upon local population size and sex ratio. If the population is relatively low, and the numbers of female and males are approximately equal, paired courtship and spawning occurs. If, however, the population size is larger and males outnumber females, then a different strategy prevails. In this case, males form floating leks at sunset to display to larger females as the latter move about the spawning site. One male may be more successful and joins the female as she rises into the water column to release her eggs. As the female and male ascend, however, they are joined by other males, who all contribute sperm toward the fertilization of the eggs. Females do appear to exercise control over the timing of the spawning and the composition of the group. Unlike females of many other pelagic spawning reef species, female lizardfishes may spawn more than once during an evening. As courtship continues, the female rises to spawn again and is joined by more than one male. If, however, only one male joins her, she will abort the spawning ascent, return to the bottom, and wait for courtship from the group of males to resume. Females seem to pursue this strategy of group spawning in order to assure complete fertilization of their egg masses. The male closest to her in an ascent, the one she chooses from the others as the most attractive, will likely fertilize a significant proportion of her eggs, but the contributions of the other males may promote both genetic diversity and completion of the job!

Feeding behavior

Fishes use a variety of behaviors while feeding to detect and capture prey, extract plant materials, or to sift sediments to extract objects of nutritional value. Planktivory by fishes occurs during the day and at night. During daylight, hovering planktivores such as fairy basslets (Serranidae: Anthiinae), some freshwater sunfishes, damselfishes, angelfishes, certain triggerfishes (Balistidae), and many other species, feed upon zooplankton or phytoplankton by plucking individual plankton out of the water column. Plucking is accomplished with specialized mouthparts or by rapid movements of the mouth. The mola (Molidae), and other species that feed upon macroplankton or mesoplankton in the water column, forage in a similar fashion. Garden eels (Congridae) and other burrow-dwelling planktivores emerge partially from their burrows to feed upon plankton that drift past in the current. Schools of fusiliers (Caesionidae) dart erratically in the water column as they grab and feed upon plankton they detect there. Alternately, fishes such as whale sharks (Rhyncodontidae), basking sharks (Cetorhinidae), manta rays (Mobulidae), herrings, anchovies (Engraulidae), scads (Decapterus spp.; Carangidae), and similar species open their large mouths and strain the plankton from the water column as they swim. Fishes with smaller mouths, such as reef herrings and flyingfishes (Exocoetidae), also strain plankton in the water column. At night, a new set of planktivores emerges from shelter to feed upon pelagic and demersal plankton in the water column. These include squirrelfishes and soldierfishes (Holocentridae), cardinalfishes (Apogonidae), bigeyes (Priacanthidae), along with a host of deep-dwelling species. These fishes use their large eyes and other well-developed senses to detect and feed upon plankton.

Herbivory in marine fishes is more pronounced in tropical than in temperate species. Among the tropical fishes, halfbeaks (Hemirhamphidae), sea chubs (Kyphosidae), damselfishes, parrotfishes (Scaridae), blennies (Blenniidae), rabbitfishes (Siganidae), and surgeonfishes (Acanthuridae), are the prominent groups. In freshwater systems, numerous species feed upon benthic algae, emergent plants, and even seeds and fruits from terrestrial plants. Some marine groups, such as the butterflyfishes, angelfishes, filefishes (Monacanthidae), and triggerfishes, include species that are omnivorous and feed upon benthic algae. In temperate marine waters, some members of the Sparidae (porgies), Kyphosidae, Aplodactylidae (sea carps), Odacidae (rock or weed whitings), and

Stichaeidae (pricklebacks) are more dependent upon plant life. Freshwater omnivorous species, such as the carp and its relatives (Cyprinidae), and a number of characins (Characidae), often include plant materials as a significant part of their diet.

Herbivores feed by grazing or browsing, and are capable of learning what species of plant are edible and what are toxic. Access to edible benthic algae, sea grasses, or other plant materials may be as simple as swimming into a given area and stopping to graze or browse. Parrotfishes feed on zooxanthellic algae contained in coral skeletons by using their specialized beaks scrape algae off rocks or dead corals. They also bite off chunks of the coralline skeleton as they graze. The parrotfish's pharyngeal teeth crush the chunk within the mouth cavity, swallow and extract the algae, expel the resulting coralline sand. Territorial species, such as certain damselfishes known as "farmer" fishes, actively maintain patches of desirable species of algae that they tend, defend, and feed upon. Other herbivores attempting to feed upon this patch (or patches of algae not tended, but within the territory of any herbivorous species) are turned away. Fishes defending the patches must be overwhelmed before other herbivores can gain access to this resource. One way to accomplish this is for the grazing or browsing species to form schools that can move into a territory and easily outnumber the defender. One form of this type of school, the heterospecific or mixed-species shoal or school, consists of fishes of a number of species (including nonherbivorous fishes) that move about the bottom. Membership in the school is temporary, and its members not only gain protection from schooling but, more importantly, are able to breech the defenses of a territorial herbivore to feed upon the algae it attempts to protect.

Feeding by herbivorous monospecific schools takes place both at night and during the day. For example, unicornfishes (Acanthuridae) form schools that graze on sea grass flats at night. Their efficiency at feeding upon sea grass and benthic algae there is analogous to a giving the flat a good haircut.

Predators rely heavily upon one or more sensory systems in their search for prey. Among benthic species, ambush predators such as scorpionfishes (Scorpaenidae), flatheads (Platycephalidae), and sculpins (Cottidae) use vision to detect passing prey. Scorpionfishes and many sculpins remain motionless until they detect prey and estimate the distance to it. The predator then engulfs the prey by rapidly opening its mouth and sucking it in. Flatheads grab the prey with a mouthful of teeth, and manipulate and swallow it. Other ambush predators, such as lizardfishes or hawkfishes, launch themselves into the water column or down to the substrate to grab prey. Freshwater pikes and pickerels (Esocidae), groupers, basses (Centrarchidae), the Murray cod (Percicthyidae), and the barramundi (Centropomidae) utilize structures, such as submerged trees and stumps or weed beds, to mask their presence as they ambush passing prey. Their acute vision allows various trout species in streams to identify and assess aquatic insects carried by surface and subsurface currents. At night, the enlarged eyes of many nocturnal predators allow them to detect, track, and attack prey on the bottom or in the water column.

Other sensory systems, such as taste, touch, and chemoreception, allow fishes that prey on benthic invertebrates and smaller fishes, such as catfishes (various families), goatfishes, threadfins (Polynemidae), freshwater eels (Anguillidae), and moray eels (Muraenidae), to detect prey buried just beneath the surface of the substrate. Similarly, electrical receptors known as ampullae of Lorenzini allow elasmobranches, such as sharks and rays, to detect minute electrical currents generated by prey buried beneath sand, rubble, or mud; locate their position; and feed upon them. Knifefishes (Gymnotiformes) of South America and the Mormyridae of Africa use other organs to generate weak electric fields that allow them to detect prey in murky water.

In the pelagic realm, vision, olfaction, touch, and sound detection are important sensory components of predatory behavior. Swiftly moving predators, such as tunas (Scombridae) and billfishes (Istiophoridae), rely upon keen eyesight to track and hunt their swiftly moving prey. Predators, especially sharks, also rely upon the smell of prey, and in particular, the smell given off by injured prey, to detect them. Low frequency sounds generated by the movement of prey, whether swimming or struggling, are detected by the predator's lateral line system. These vibrations are felt, rather than heard, by the lateral line receptors. Higher frequency sounds generated by prey are detected by the inner ear and direct it to the location of the prey.

In deepwater environments, visual capabilities may be reduced in favor of other senses in some species, but accentuated in others. Deepwater predators with large eyes can detect bioluminescent flashes generated by potential prey. Chemoreception, hearing, and lateral line senses are also important in prey detection in waters where darkness prevails and little or no light penetrates from above.

The pursuit of prey varies among predatory species. Ambush predators frequently employ camouflage and position themselves among rocks, corals, or marine plants to conceal themselves until they can detect and ambush prey. Some ambush predators use lures fashioned from modified fin rays or other body parts. These lures, which may resemble a small fish or invertebrate in shape, are waved about to attract the prey. This behavior, sometimes referred to as aggressive mimicry, occurs in a few shallow and deepwater predatory families of fishes. In deepwater species, the lure may be bioluminescent. Other predators, such as juvenile snappers (Lutjanidae) or hamlets (Serranidae), mimic nonthreatening species such as damselfishes to get closer to prey. Predators, such as trevallys (Carangidae), often rapidly patrol the bottom throughout the day and night in search of prey that cannot retreat to shelter quickly enough to escape being eaten. These predators may also attack schooling baitfish species in the water column singly, in pairs, groups, or schools. Barracudas (Sphyraenidae) rest motionless in the water column, then strike rapidly, sometimes over a distance of several meters, at an unwary fish in the water column or on the bottom. Schools of salmon, striped basses (Moronidae), amberjacks (Carangidae), bluefishes (Pomatomidae), and tuna (Scombridae) rapidly chase and slash schools of fleeing baitfishes, and may also herd them while attacking. Other species, such as some barracudas and lionfishes (Scorpaenidae), hunt in packs and often utilize structures, including reef and cave walls and even suspended fishnets, to act as barriers to aid in escape. At sunset, a pack of lionfishes assembles and gathers near a school of sweepers (Pempheridae) that is emerging for the night. Then the lionfishes extend their large pectoral fins and use them to push the sweepers into an increasingly small aggregation that is ultimately trapped between the pack of lionfishes and the reef wall. The predators then rapidly inhale the sweepers with their large mouths as they try to escape. Other predators, such as groupers and large soapfishes (Serranidae), take advantage of this behavior to ambush escaping sweepers.

Many species detect prey hidden in bottom sediments and then dig or sift them out. A number of these predators have specialized teeth, mouths, or gills that allow them to do this; others fan the sediments to expose the prey. Some fishes, such as certain wrasses (Labridae) and trevallys, allow other fishes, such as stingrays and goatfishes, to do the digging for them. These predators follow the bottom-foraging species and feed opportunistically upon whatever may be exposed. Barracudas have been observed hanging motionless in the water column above nests of large triggerfishes (Pseudobalistes spp.). The triggerfishes constantly tend these nests by rearranging the substrate and turning over rocks, and in doing so they expose or startle prey fishes or other organisms. When this happens, the barracudas quickly rush down to the exposed prey and grab it before the triggerfish can respond.

Pelagic deepwater species ascend the water column as night falls and may rise hundreds of meters toward the surface as they track their prey. Some species are following the similar movements of pelagic invertebrates upon which they feed. Others track these fishes as prey, and some species, such as the snake mackerels or oilfishes (Gempylidae), have feeding behaviors that appear to be similar to shallow water species, such as barracudas (Sphyraenidae) or wahoos (Scombridae).

A number of predators employ mechanisms or behaviors that allow them to stun or otherwise immobilize their prey before they eat it. For example, torpedo rays (Torpedinidae), electric eels (Electrophoridae), electric catfishes (Malapteruridae), and some stargazers (Uranoscopidae) discharge a strong electrical current that stuns passing prey. Some wrasses (Labridae) smash their invertebrate prey with or against rocks. Archerfishes (Toxotidae) stun and knock down insect prey resting on mangrove branches or emergent grasses above the water surface by shooting a stream of water "bullets" at them. Billfishes and the swordfish (Xiphiidae) utilize their bills to herd, stun, spear, or slash their prey before eating them. Hammerhead sharks use their unique cephalic lobes to pin down stingrays, a favored prey. Sharks and barracudas use sharp teeth to capture and cut prey into smaller pieces before they are eaten. Sharks also take bites out of larger prey, such as whales, without capturing them. Relatively diminutive fishes, such as the poison-fang and fang blennies also practice this behavior. These small predators hover in the water column and launch themselves at passing fishes to bite off a scale or small piece of flesh. Fishes in the genus Aspidontus mimic blue-streak cleaner wrasses (Labroides dimidiatus), approaching fishes that may be fooled into thinking they will be cleaned, but end up being bitten. Juveniles of larger predators, such as the leatherback, Scomberoides lysan (Carangidae), also engage in this behavior. Scale-eating or biting off small pieces of flesh is also practiced in tropical freshwater fishes of Africa and South America. Specialized genera of scale-eating African cichlids (Cichlidae) include Perridodus and Plecodus from Lake Tanganyika, and Corematodus and Genyochromis from Lake Malawi. Fin-eating is practiced by characoid fishes of the families Citharinidae (genera Ichthyoborus, Mesoborus, and Phago from Africa) and Characidae (subfamily Serrasalminae, the piranhas and their relatives; genera Catoprion and Serrasalmus from South America).

Cleanerfishes, including the cleaner wrasses Labroides and Labropsis (Labridae), cleaner gobies (Gobiosoma), and some butterflyfishes establish cleaning stations along coral or rocky reefs, where they attract and clean the "client" fishes that approach. The cleaners swim in a regular pattern of movements. The client fishes, responding to the swimming behavior and distinctive color pattern of the cleaner, as well as to the location of the cleaning station, assume a posing posture to signal that cleaning is required and may begin. The cleaners then forage along the client's body, feeding on parasitic copepods and other parasitic organisms, along with any damaged tissues. Cleaner wrasses and gobies also enter the mouths and gill cavities of their clients, including large predators like groupers and moray eels, without being preyed upon. This type of behavior is a mutualistic symbiosis, because both the cleaner and the client benefit. Cleaning behavior has also been observed in freshwater fishes, including some members of the family Cichlidae. A pelagic variation of this behavior is practiced by remoras or sharksuckers (Echeneidae). These fishes attach themselves to large predators, such as sharks, billfishes, turtles, and whales, and hitchhike as their hosts swim. In turn, the remoras feed upon parasitic copepods on the host, but will also take advantage of scraps left over from the host's feeding bouts. This behavior is a commensalistic symbiosis, in that the cleaner gains while the client neither benefits or loses out.

Parasitism by marine fishes is not a common strategy, but it does occur in a number of different species. Internal parasites include the pearlfishes (Carapidae) that live in the gut cavities of seacumbers and large starfishes, where they feed upon gut tissue. The eel-like Simonchelys parasitica (Synaphobranchidae) has been found burrowed into the flesh of various bottom-dwelling fishes, but has also been recorded from the heart of a mako shark, a fast-swimming pelagic species. In freshwater fishes, however, catfishes of the tropical Amazon family Trichomycteridae are parasitic. Most species attack gill tissues of larger fishes, but members of the genus Vandellia are known to parasitize the urethra of mammals, including humans, causing considerable harm. Lampreys (Petromyzontidae) are external parasites, which attach themselves to the skin of their prey and feed upon tissue and body fluids with their specialized mouths.

Fishes that feed upon detritus use their mouths to scoop up sediments, from which they extract detrital materials with their pharyngeal teeth and expel sediments through their gills. Scavengers feed upon dead and dying fishes or other organisms and play an ecological role. Fishes bite or peck at the body of the organism to remove chunks of flesh. Some fishes, such as the deepwater hagfishes (Myxinidae), are specialized to enter the body cavity of dead fishes to feed upon them internally.

Predator avoidance behavior

Marine fishes have evolved a number of mechanisms and behavioral strategies to avoid predation. These include color patterns and modifications of body structure to provide camouflage, mimicry, or warnings of toxicity. Color patterns that disrupt the fish's outline, reduce its contrast against background coloration, or allow it to blend into the background all provide camouflage and protection from predation. These same attributes also favor predators who wish to hide from their prey. Countershading (dark color dorsally and pale or white ventrally) and reverse countershading (pale or white dorsally and dark ventrally) obscure the fish when it is viewed from above or beneath. A silvery or mirrorlike coloration, as seen in herrings, tarpons (Megalopidae), ladyfishes (Elopidae), smelts (Osmeridae), carps and minnows, and mullets (Mugilidae), reflects light and confuses potential predators. Fishes that are relatively transparent, such as in the glassfishes (Channidae) and some cardinalfishes, are difficult to see, especially in low light conditions. Similarly, modifications to the skin, fin rays, or other portions of the body can convey similar benefits. For example, the sargassumfish (Antennariidae) has modifications, which, in conjunction with its greenish brown coloration and hovering behavior, allow it to resemble sargassum algae. Pipefishes and seahorses (Syngnathidae), and some filefishes, have similar adaptations. Adult leaffishes (Nandidae) and juveniles of a number of species, including spadefishes and batfishes (Ephippidae), combine a color pattern with behavior to resemble inedible objects such as leaves.

Warning coloration informs potential predators that a fish is (or is giving the impression of) being toxic and should be ignored. The juveniles of some species of sweetlips (Haemulidae) have color patterns and behaviors that allow them to mimic toxic nudibranches and flatworms. Other fishes with toxins in their skin or organs, such as various tobys or sharp-nose puffers (Canthigaster spp.; Tetraodontidae), have color patterns that advertise their toxicity. One species of filefish, Paraluteres prionurus, is nonpoisonous, yet is afforded protection from predation because it has a color pattern and behavior that exactly mimics the black saddled toby (Canthigaster valentini), and, to a lesser extent, the crowned toby (C. coronata).

Behavioral responses to perceived threats detected by senses such as vision, hearing, the lateral line, and smell may be rapid or subdued. These responses are used by solitary individuals but are accentuated in aggregations or schools. Many species react swiftly to the sight of an approaching predator or to the detection of noises or pressure waves generated by its approach. Flight avoidance, usually in the form of rapid or erratic swimming away from the predator, occurs in the water column. Some species, such as flyingfishes, halfbeaks, and needlefishes (Belonidae), leap above the surface of the water and may coast for a few to several meters in the air before entering it again. As a school or aggregation, reef herrings and other baitfishes leap repeatedly into the air as they flee approaching predators. Schooling behavior provides significant predation avoidance benefits because of the fact that there is safety in numbers. Most predators have to target a single individual to successfully prey upon it. The presence of many individuals within a school means that, with more prey to choose from, the chances of any one healthy individual of being preyed upon is reduced as the school takes flight.

Fishes with less energetic responses than the reef herrings, such as lionfishes and other scorpionfishes, merely erect pectoral and dorsal fins that have poison-tipped spines to detract predators. Other fishes with poisonous spines show a similar behavior. Adult pufferfishes (Tetraodontidae) and porcupinefishes (Diodontidae) inhale water and inflate their bodies to avoid predation by all but the largest predators. These fishes may also be poisonous or have spines that make ingesting them difficult. Other species, such as garden eels (Congridae), sanddivers (Trichonotidae), tube blennies, burrowing gobies, and triggerfishes duck into holes or burrows. Triggerfishes can "lock themselves in" their holes by extending their dorsal and anal fin spines. Similarly, soles (Soleidae), flounders (Bothidae), and their relatives bury themselves in the sand. At night, sleeping parrotfishes wedge themselves into the reef and secrete a somewhat gelatinous cocoon that allows it to detect predators by touch if the cocoon is violated.

Another behavior normally attributed to birds but also observed in some species of reef and freshwater fishes is mobbing. Mobbing serves to ward off an intruding predator by displaying to or attacking it in number, but also to warn conspecifics of the intruder. For example, the damselfish Pomacentrus albifasciatus maintains territories adjacent to conspecifics on reef flats. If a predator, such as a moray eel or scorpionfish, enters the area, those damselfishes closest to the intruder rise into the water column and display their erect fins as they dance in front of, behind, or along the flank of the intruder. These damselfishes are soon joined by others from the territorial matrix, and together they mob the intruder until it leaves the area. This damselfish also appears to be able to recognize which kind of danger the intruder may pose before mobbing it. If the intruder is a scorpionfish, the damselfishes avoid displaying near its head and focus their attacks along the posterior flank or tail, presumably because scorpionfishes have large mouths and are capable of extremely rapid feeding attacks. However, if the intruder is a moray eel, the damselfishes also mob in the region of its mouth because it is relatively smaller and the eel's feeding behavior is different.

Behavior, evolution, and conservation

The behavior patterns in fishes evolved over countless generations, largely in response to pressures from natural and sexual selection. These behavior patterns are distinct and measurable, and they are just as much characteristics or traits as those based upon morphology or biochemistry. Although general patterns among different, and often quite divergent, species exist, the applications of these patterns and their subtle differences are often unique. Similarity in patterns may be a function of convergent evolution, common descent among related groups, or an affinity among species. Differences in patterns may be the result of a lack of affinity or may be subtle changes in application within a group of closely related species. The study of phylogenetic relationships among species by the comparative method provides an understanding of the patterns of behavior observed, as well as the processes that underscore their evolution within species. This field of study, known as historical ecology, has great utility in ascertaining patterns of character development between and within species, and has predictive power in instances where information on a particular species within a group of related species is relatively lacking. This method also allows for testing hypotheses that may confirm the validity of the prediction.

The methods of historical ecology in the study of fish behavior have considerable utility as tools for predicting how fishes behave under exploitation, habitat destruction, or other problems addressed in the science of conservation biology. Conservation efforts, especially in highly diverse systems, are often stymied because of a lack of information on the biology and behavior of some fishes within those systems. As detailed studies of most groups are lacking, some considerable effort has been expended upon understanding the biology and behavior of a relatively few species within these systems. Generalizations are feasible for attempting to understand species that are less well studied. However, only the steady collection of data coupled with the predictive advantages of historical ecology allows scientists to understand the larger picture so they can convey to fishery managers the information necessary for the design and implementation of effective conservation and management plans.

Resources

Books

Briggs, J. C., and J. B. Hutchins. "Clingfishes and Their Allies." In Encyclopedia of Fishes, edited by J. R. Paxton and W. N. Eschmeyer. San Diego: Academic Press, 1998.

Brooks, D. R., and D. A. McLennan. Phylogeny, Ecology, and Behavior. Chicago: University of Chicago Press, 1991.

Donaldson, T. J. "Assessing Phylogeny, Historical Ecology, and the Mating Systems of Hawkfishes (Cirrhitidae)." In Proceedings of the 5th Indo-Pacific Fish Conference, Noumea 1997, edited by B. Seret and J. Y-Sire. Paris: Societé Française, Ictyologie, 1999.

Helfman, G. S., B. B. Collette, and D. E. Facey. The Diversity of Fishes. Oxford: Blackwell Science, 1997.

Moyle, P. B., and J. J. Cech Jr. Fishes: An Introduction to Ichthyology. 3rd edition. Upper Saddle River, NJ: Prentice-Hall, 1996.

Myers, R. F. Micronesian Reef Fishes. 3rd edition. Barrigada, Guam: Coral Graphics, 1999.

Pitcher, T. J., ed. The Behaviour of Teleost Fishes. London: Chapman and Hall, 1993.

Potts, G. W., and R. J. Wootton, eds. Fish Reproduction: Strategies and Tactics. London: Academic Press, 1984.

Thomson, D. A., L. T. Findley, and A. N. Kerstich. Reef Fishes of the Sea of Cortez. 2nd edition. Tucson: University of Arizona Press, 1987.

Thresher, R.E. Reproduction in Reef Fishes. Neptune City, NJ: T.F.H. Publications, 1984.

Wootton, R. J. Ecology of Teleost Fishes. London: Chapman and Hall, 1990.

Periodicals

Balon, E. K. "Reproductive Guilds of Fishes: A Proposal and Definition." Journal of the Fisheries Research Board of Canada 32 (1975): 821–864.

——. "Additions and Amendments for the Classification of Reproductive Styles in Fishes." Environmental Biology of Fishes 6 (1981): 377–389.

Donaldson, T. J. "Mobbing Behavior in Stegastes albifasciatus (Pomacentridae), a Territorial Mosaic Damselfish." Japanese Journal of Ichthyology 31 (1984): 345–348.

——. "Lek-Like Courtship by Males and Multiplespawnings by Females of Synodus dermatogenys (Synodontidae)." Japanese Journal of Ichthyology 37 (1990): 292–301.

——. "Mating Group Dynamics and Patterns of Sneaking by Dominant Male Sandperches, Parapercis snyderi (Pinguipedidae)." Unpublished manuscript in review.

Lassuy, D. R. "Effects of 'Farming' Behavior by Eupomacentrus lividus and Hemiglyphidodon plagiometapon on Algal Community Structure." Bulletin of Marine Science 30, Special Issue (1980): 304–312.

Thresher, R. E. "Clustering: Non-Agonistic Group Contact in Territorial Reef Fishes, with Special Reference to the Sea of Cortez Damselfish, Eupomacentrus rectifraenum." Bulletin of Marine Science 30, Special Issue (1980): 252–260.

Terry J. Donaldson, PhD

Behavior

Behavior consists of all an animal's reactions to messages received by the central nervous system from any of the several sensory systems of the body. Herpetologists have been most interested in behaviors that have clear functional significance, such as behaviors involved in obtaining food, avoiding danger, finding mates, thermoregulating, and moving between microniches at alternate times of the active season (e.g., migration from hibernacula to feeding grounds and vice versa, migration from feeding grounds to oviposition sites and vice versa, and moving between feeding grounds).

For many vertebrates, vision is the most vital of all the senses, followed generally by hearing. In most reptiles, however, chemical sensitivity is as vital as vision, or more so. As in other vertebrates, olfaction is mediated by the paired nasal organs, which open to the exterior through the nostrils. In reptiles, however, additional mediators of chemical sensitivity are the paired vomeronasal organs, the openings of which are at the anterior extremity of the roof of the mouth, close to the nasal organs. In general, the nasal organs are sensitive to airborne or volatile chemicals, whereas the vomeronasal organs are sensitive to substrate-borne or nonvolatile chemicals. Hearing air vibrations varies in importance across reptilian taxa, although there is a general sensitivity to lowfrequency vibrations propagated through the substrate. Touch and taste receptors exist in reptiles, and they play important roles in mediating certain behaviors, but considerable variation exists across species. Sensitivities to polarized light, infrared radiation, and geomagnetism are known to play significant roles in some taxa, but analysis of these sensory processes is in its infancy.

Behaviors guided by chemical senses

Chemical guidance of predatory behavior has been extensively studied in snakes and lizards. Many species exhibit attack and ingestive behaviors on presentation of chemical cues derived from prey. In these experiments, the chemicals typically are presented on cotton-tipped applicators in the absence of any visual or tactile cues associated with prey. Therefore we can be certain that chemicals alone are responsible for triggering the predatory actions. This does not mean that garter snakes (Thamnophis sirtalis), for example, pay no attention to other stimuli arising from prey (fish, salamanders, frogs, worms) under natural conditions. We know that cues such as movement are vital for attracting the snakes' interest. Yet if investigatory behavior does not bring the snake into contact with appropriate chemical cues, the snake is unlikely to bite the target. Visual cues may command attention and lead to careful inspection, whereas chemical cues trigger the final consummatory acts. Of considerable interest is that neonatal garter snakes exhibit such responses to certain chemical cues before having any experience with prey. This finding leads to the conclusion that responses to these cues are innate. Furthermore, neonatal garter snakes born in different parts of the geographic range respond most strongly to different prey extracts. This finding indicates that subpopulations of snakes have experienced differential selection based on variation in prey abundance. In general, the chemical cues to which snakes respond most strongly are those associated with prey that happen to be available in the snakes' habitat. Changes in prey populations are followed by changes in prey recognition mechanisms within the snake population.

Because reptiles possess nasal and vomeronasal chemosensory systems, herpetologists have been keen to learn the relative contributions of these two systems to predatory behavior. Experimenters have developed various techniques for blocking one or both of the systems to study predatory behavior. Garter snakes have been subjects of most of these investigations, although a few studies have involved western rattlesnakes (Crotalus viridis). The common result has been that prey recognition remains undisturbed when the nasal system is blocked but that this behavior almost disappears when the vomeronasal system is blocked. In some particularly elegant experiments, the blocks were reversible, and restoration of the vomeronasal system was followed by a return of the abilities to recognize and respond appropriately to prey. This body of research leaves no doubt about the importance of the vomeronasal organs.

The role of the nasal system and its interaction with the vomeronasal system remains a matter of speculation. Most investigators believe that the nasal system is extremely sensitive but not particularly discriminatory, whereas the reverse is true of the vomeronasal system. The nasal system is thought to serve an alerting function. It informs the snake that something of interest is nearby and sets the vomeronasal system in motion in the form of tongue flicking. Vomeronasal examination

can identify the molecules in question and activate the appropriate behaviors. In this view, nasal olfaction functions as vision or detection of vibrations does in that ambiguous stimulation of any of these senses can activate tongue flicking so that the animal can conduct a definitive examination. Unambiguous stimulation of any sense, usually by an approaching predator, typically activates immediate escape without the need for cross-modal verification. Detection of potential prey is frequently an ambiguous matter because of prey crypsis (camouflage) and consequent reduction in intensity of stimuli and requires the synergistic action of multiple sensory systems. In the latter context, the vomeronasal system performs the "gold standard" test, and the other senses invite the vomeronasal system to conduct the test.

The vomeronasal system plays an equally important role in the reproductive behavior of garter snakes. In experiments, males with impaired vomeronasal systems did not follow the trails of estrous females and did not attempt to court or copulate with such females when they encountered them. When the vomeronasal systems of the males were restored, normal sexual behavior reappeared, including the ability of the males to follow trails deposited by females. Male garter snakes

differentiate the trails of conspecific and heterospecific females only through chemical cues. Males can differentiate large and small (but reproductively mature) conspecific females with chemical information alone. In experiments, males preferred chemical cues from large females over those of smaller females, a fact probably correlated with the greater number of eggs produced by large females. In other words, mating with larger females produces greater fitness benefits for males than does mating with smaller females, and males reflect the effect of this selective pressure in their chemosensory preferences. When the length of females was controlled but mass was varied, males preferred the heavier females and did so when only chemical information was available. Male garter snakes apparently can use chemical information to discriminate females of varying nutritional conditions. This capability probably is associated with an effect of nutritional condition on quantity and quality of eggs produced by females.

Although few other reptile species have been studied in as much detail as have garter snakes, especially T. sirtalis, we know that male skinks can do some of the things that male garter snakes can do. In particular, male skinks can differentiate conspecific and heterospecific females with only chemical cues. Likewise, female skinks can differentiate chemical cues of conspecific and heterospecific males. It seems probable that male skinks also are able to differentiate conspecific females of varying size and condition, but these phenomena have not yet been tested. Nor has anyone tested whether female skinks or garter snakes can differentiate chemical cues derived from males of varying size or condition. We assume the vomeronasal systems of garter snakes and skinks are responsible for discrimination, but this has not yet been demonstrated in experiments that block the vomeronasal system while the olfactory system is unimpaired.

Chemical cues associated with predators are detected by various reptiles. The result is avoidance or other self-protection reactions. We cannot yet be certain that the vomeronasal system mediates these reactions because appropriate blocking experiments have not been conducted, but this is a reasonable hypothesis.

Some reptiles have been shown to discriminate between their own chemical cues and those of conspecifics. Some male reptiles can differentiate male conspecifics on the basis of chemical cues. Experiments along these lines have been done with rattlesnakes, desert iguanas, and sand swimming skinks. It is likely the abilities will be found to be widespread. A number of benefits can be derived from individual recognition, including the interesting social dynamic known as the "dear enemy" phenomenon. Common among territorial birds, the phenomenon consists of individual recognition by neighboring territorial males. These animals respect the boundaries between their territories and do not intrude on each other; thus each animal is allowed to relax the level of vigilance and aggressive behavior that would otherwise be devoted to boundary patrolling and defense. If one of the males is replaced with a new individual, the remaining neighbor exhibits an immediate elevation in vigilance and defense, revealing that he notices that his former dear enemy is no longer present. Eventually the original territory owner and the new neighbor enter a dear enemy relationship, so that each can save energy and avoid injury from fighting. The dear enemies enjoy mutual benefits by respecting each other's property rights. Because individual recognition is clearly an important component of this behavior, the dear enemy phenomenon is generally thought to be an advanced form of social interaction. This does not mean that it is found only in birds and mammals; the behavior has been shown to occur in salamanders and lizards. Whether it occurs in any species of snake, turtle, or crocodilian is conjectural at this time, although a chemosensory basis for the phenomenon clearly exists in at least some species.

Perhaps the most intriguing chemosensory behaviors of reptiles involve venom. Venom immobilizes and kills prey and contains powerful enzymes that greatly facilitate digestion. In experiments, rattlesnakes given a choice between envenomated and nonenvenomated mice otherwise equal in size, age, and sex selected the envenomated prey more frequently than they did the nonenvenomated prey. This remained true when the mice were wrapped in dark nylon mesh that blocked visual or tactile cues; thus we can be certain that chemical cues mediated the selection. When rattlesnakes were given a choice between a trail deposited by an envenomated mouse and one deposited by a nonenvenomated mouse, the snakes reliably selected the former trail, a finding that again indicates chemical cues mediate the behavior.

To understand how sensory bias might contribute to a snake's fitness, it is necessary to understand that rattlesnakes and many other venomous species are ambushers that strike and release adult rodent prey. This style of predation avoids injuries that could occur if struggling rodents were held in the snake's jaws after the strike. Although the venom kills the prey, the process takes as long as several minutes, during which the rodent's teeth, claws, and guard hairs can inflict serious damage. Releasing the rodent after the envenomating strike minimizes the snake's risk of injury, but the snake risks losing the prey, which can travel several meters from the site of attack while the venom takes effect. Recovering the rodent carcass becomes difficult, partly because the immobilized rodent no longer emits motion cues to attract the snake's attention and partly because the rodent may be behind objects or in a burrow, so thermal information (i.e., infrared radiation detectable by pit organs) is obscured or blocked entirely. Recovery of the rodent carcass therefore is mediated by chemical cues detected by the vomeronasal system. A rattlesnake that has delivered a successful predatory strike is capable of following the rodent's chemical trail with exactitude, even though the same snake usually does not follow such a trail in the absence of a predatory strike. The strike is necessary to trigger chemosensory searching and trail-following behavior. This is true for rattlesnakes; cottonmouths (Agkistrodon piscivorus), however, follow trails effectively whether or not a predatory strike has been delivered before the snake encounters the trail. Gila monsters (Heloderma suspectum) and Australian sand goannas (or monitors) Varanus gouldii, behave as cottonmouths do. For these predators, chemical cues on the substrate are sufficient to induce trail following, and this behavior may be associated with a propensity to search for carrion. For rattlesnakes and various other vipers, chemical cues on the substrate usually are not sufficient, and a successful predatory strike is critical.

In the case of rattlesnakes, two trails always are present in the poststrike environment, one deposited as the prey wanders into striking range (the preenvenomation trail segment) and one deposited as the prey moves away from the site of attack (the postenvenomation trail segment). Following the wrong, or preenvenomation, segment could result in losing the prey, wasted energy, and vulnerability to predators. It is not surprising that rattlesnakes discriminate the two trails and select the postenvenomation segment. What is the chemical basis for this fascinating discrimination?

Venom is a complex material, containing well over 30 identifiable fractions, some of which are lethal to rodents, some not. The latter fractions are thought to be synergizers or amplifiers, not necessarily harmful in themselves but capable of increasing the damaging effects of other fractions. Finding the particular fractions responsible for the snake's discrimination of pre- and postenvenomation trail segments is almost impossible. One reasonable hypothesis is that proteolytic enzymes, major constituents of venom, are responsible. The idea is that such enzymes break down rodent protein and contribute to immobilization, death, and digestion of prey and that the snakes have evolved a perceptual sensitivity to these effects. This sensitivity facilitates the important task of locating and following the postenvenomation trail segment. In other words, proteolytic enzymes have an initial or primary function, and they have acquired a secondary one because of the snake's ability to perceive some of these primary chemical effects. Another hypothesis is that specialized components have been added to venom, not necessarily because of their

lethal effects but because of their perceptual, trail-enhancing effects. The term "trail marker substance" can be used in recognition of the idea that the venom component has acquired its perceptual role not secondarily but as its primary (and perhaps only) function.

Differentiating these hypotheses hinges on the fact that rattlesnake venom passed through gel filtration columns separates into fractions according to molecular weight and that proteolytic enzymes sort into several fractions while other fractions contain little or none of this material. Therefore it is possible to use these various fractions as experimental injectants. That is, mice given injections of each of these fractions suspended in distilled water can be paired with control (nonenvenomated) mice and presented to rattlesnakes. If proteolytic enzymes are the critical elements, then snakes ought to be able to discriminate mice injected with these enzymes from control mice. If such mice cannot be differentiated from controls, one implication would be that some other venom fraction is the critical one. The result in experiments with western diamondback rattlesnakes (Crotalus atrox) has been that proteolytic enzymes do not cause a mouse to be discriminated from a control but that another fraction (containing no proteolytic enzymes) has this effect. The chemical composition of this fraction has not yet been identified, but the indications are that the second hypothesis is correct. This work underscores the subtlety of the chemical cues used by reptiles. Reptiles can detect gross cues, such as those associated with rotting carrion, and they can use remarkably subtle cues in remarkably low concentrations.

Ambush predators must first select an appropriate site, a place which prey are likely to visit or to pass through. Several reptiles have been shown to make this selection on the basis of chemical cues deposited by prey that have recently moved through the site. Prairie rattlesnakes making their vernal migration would stop if they were to encounter fresh chemical cues derived from deer mice (Peromyscus maniculatus). Once the rattlesnake occupies an ambushing site, however, it usually waits until a successful predatory strike is delivered before paying any further attention to chemical trails. There are exceptions, of course: Some snakes engage in active foraging for burrows containing the neonates of various small mammals, and this search is undoubtedly guided by chemical cues. Thus strikes are not always necessary to activate chemosensory searching. It seems likely that reptiles of many species can use chemical cues to discriminate large versus small populations of prey and to differentiate sites currently occupied by prey from sites previously occupied but now abandoned. Evidence along these lines has been collected, but a great deal of research remains to be done on the topics of habitat selection and chemical ecology.

Although heavy reliance on the nasal and vomeronasal senses is characteristic of many species of reptiles, particularly the most advanced species, numerous species are less reliant on chemical cues than on visual information. Chameleons are examples not only in their use of visual cues in locating and capturing prey but also in their use of visual cues in social and reproductive behavior. Interspecific variation exists among reptiles in the modalities that mediate important behaviors. Therefore statements about the role of vomeronasal stimulation should not be generalized to all reptiles. The relationships between type of food, behaviors involved in acquiring food, and the sensory modalities used are a major area of herpetological investigation. Herbivorous lizards have been found to behave in surprising ways. These animals not only detect edible plants through chemical cues but also detect and reject other plants on the basis of the presence of defensive compounds. Herpetologists have made theoretically important discoveries regarding the chemical senses of reptiles, but we have probably only scratched the surface.

Behaviors guided by vision

Visual cues, usually in the form of prey movement, have long been known to attract a snake's attention and to elicit predatory responses in insectivorous lizards. Equally interesting is the role of visual information in social and reproductive behavior of lizards. Chameleons exhibit "emotional colors" that involve changes in brightness during agonistic interactions and culminate in victory or submission, each with a characteristic pattern. It is partly through these color changes that chameleons have acquired their protean reputation. Iguanian lizards execute a set of movements, including head bobs, pushups, and dewlap extensions, combined in particular sequences that are species specific not only with respect to sequence but also with respect to cadence. Females of sympatric species can discriminate conspecific from heterospecific males on the basis of these display properties. Males use the displays to advertise territories and to settle boundary disputes with other males.

Results of experiments involving presentation of models to territorial males have established that color patterns and postures contribute to agonistic and courtship activities. These behaviors have been found to be innate, and the development of the behaviors is not influenced by social stimulation. Some display elements of the green anole (Anolis carolinensis) are present immediately after hatching, whereas other elements emerge later in ontogeny. Even in the later stages, social stimulation appears unnecessary, because the behaviors usually emerge on schedule in animals that live in social settings or in experimental isolation. This characteristic represents a major difference between green anoles and birds and mammals, both of which typically depend on early social stimulation for the proper development of social signals. Because only the green anole has been studied extensively in this regard, we look forward to comparable projects with additional reptile species. Only when such work is completed will we know whether the developmental characteristics of the green anole are common among reptiles. The indications are that the green anole is a reasonable model for reptiles in general, and many herpetologists believe this to be the case, but more taxa must be analyzed.

Reptiles use visual cues as lures for prey. The alligator snapping turtle (Macrochelys temminckii) is probably the best known example because of the wriggling wormlike process attached to the floor of the turtle's mouth. The animal remains motionless with jaws agape while the "worm" attracts fish, which are engulfed by a profound oral snap. Several snakes (e.g., the sidewinder rattlesnake [Crotalus cerastes] and the massasauga [Sistrurus catenatus]) use their tails as lures, in some cases only during the juvenile stage of life. As the snakes grow, they experience an ontogenetic shift in prey preferences such that caudal luring for lizard or frog prey is abandoned in favor of predation on rodents. Ontogenetic shifts in prey preferences are not uncommon, and they are associated with parallel ontogenetic shifts in habitat preferences and even in diel activity patterns. Some snakes rely on caudal luring throughout life. The best example is the death adder (Acanthophis antarcticus), which has a highly specialized tail that strongly resembles a wormlike or grublike creature and is quite attractive to lizards.

Play, learning, and plasticity

Although play behavior occurs in a few species at least under captive conditions, most species do not exhibit this phenomenon. Play observed in reptiles has not been a social phenomenon. It has involved the deployment of foraging, feeding, or other behaviors in unusual, nonfunctional contexts, sometimes aimed at inanimate objects, sometimes at humans. The players have been adults, and their playful activities have been idiosyncratic rather than common among conspecifics.

Exhibition of play behavior as a social phenomenon is a major difference between reptiles and mammals, with birds positioned in between. The usual explanation is that most reptiles have been strongly selected for precocity. Neonates are miniature versions of adults and must function effectively as predators, as avoiders of predators, and as competitors. They have no leisure to acquire behavioral skills during playful interactions with peers or by observing parents.

Even the most precocial (capable of independent activity from birth) birds and mammals have opportunities to learn,

although this process may be accelerated, as it is in filial imprinting in precocial fowl and analogous social phenomena in some precocial mammals. There are important ontogenetic effects of early social stimulation in these birds and mammals. In the more altricial (immature or helpless at birth) species, similar effects occur over a broader span of time, play being an important context for social learning. In reptiles, by contrast, such effects are less common. The usual observation is that neonates are competent at biologically significant tasks the first time they encounter the task.

This does not mean that learning is unimportant in reptiles, only that it is a less conspicuous aspect of reptile ontogeny than is the case for birds and mammals. For example, several species of turtles develop strong preferences for the foods encountered after hatching. The turtles are capable of accepting many different types of prey, but the types available at the time the turtles hatch becomes favored prey as a consequence of an imprinting-like phenomenon that occurs during early feeding experiences. Because piscine prey species can fluctuate in abundance, even replacing each other owing to normal ecological events, hatchling turtles apparently are better off without strong, innate preferences but with the capacity to form preferences after sampling foods that happen to be present in the posthatch habitat. A strong innate preference for a prey type that happens not to be available could have disastrous consequences, whereas experientially induced preferences would simply adjust the predators to prey currently in the food web.

Only when the composition of the food web is predictable or reliable does it make sense for neonates to have innate preferences. This phenomenon is well known in garter snakes.

Neonates exhibit strong preferences, on the basis of chemical cues, for prey normally present in their habitats. Even here two points are of interest. First, results of experiments have shown that neonates typically exhibit several preferences; they do not prefer only a single prey species. If one type of preferred prey is not present, another will probably be available. Second, although they have strong innate preferences, neonates are capable of acquiring new preferences on the basis of early feeding experience. If none of the preferred prey are available, hungry neonates are flexible enough to adjust to new foods.

The flexibility of adult snakes and other adult reptiles has not been studied experimentally, but the husbandry experience of zoo professionals and that of many hobbyists indicates that some species readily adjust to captivity and to the foods normally provided there, whereas other species make this transition only with great difficulty. Most rodent-eating snakes typically do well in captivity, even when captured as adults. The same is true of fish-eating species, especially if rodents are facultatively present in the natural diet, such that the snakes can be switched to rodent prey in captivity. Snakes with highly specialized diets are typically difficult to keep in captivity, but this problem usually is associated with the fact that the keeper has difficulty obtaining the necessary prey in sufficient quantity.

Even notoriously difficult species can be kept in captivity, if specialized habitat factors and required foods can be provided. This judgment is based far less on scientific data than on accumulated experience of gifted, dedicated keepers. Our experience with the viper boas (genus Candoia) is consistent with this point of view. Species that take rodents adjust well to captivity, whereas species that take lizards are quite difficult to keep, unless appropriate lizard prey are available. When such prey can be offered, the snakes accept them and remain in good flesh. Lizard prey, however, are not regularly obtainable, and because the lizard-specializing snakes do not readily switch to rodents, the snakes generally become thin and vulnerable to infections that occur as a secondary effect of nutritional compromise. This outcome is a shame because lizard-eating viper boas have pleasant personalities, being tolerant of handling without offering to bite. They could be easily maintained in captivity if the food problem could be solved. Commercially produced rodent prey are widely available in the United States. The rodents are generally free of infection and relatively free of parasites, especially dangerous ones. Wild-caught lizards are sometimes infested with microbiotic and macrobiotic organisms that can readily colonize snakes with disastrous consequences. This is another reason that rodent-feeding snakes have an advantage in captivity.

Although rodent-feeding snakes usually are easy to keep in captivity, there are exceptions. One of the most famous is the eastern diamondback rattlesnake (Crotalus adamanteus). Neonates born in captivity do fairly well, but wild-caught adults rarely thrive, even under the best husbandry conditions. This fact is all the more interesting because western diamondbacks are no less aggressive and no less likely to remain aggressive in captivity, yet they generally do reasonably well, accepting prey readily and breeding with alacrity when given the opportunity under appropriate thermal conditions. Neonatal western diamondbacks born in captivity usually are calmer than wild-caught adults, but the latter usually manage to do well in captivity even with their notorious dispositions. Why wild-caught adult eastern diamondbacks and western diamondbacks differ in their tolerance of captivity remains a mystery that probably involves a difference in behavioral and emotional plasticity. Unraveling this mystery will not only shed light on the dynamics of these species but also contribute to the ability to manage many other species in captivity. Problems similar to those among wild-caught eastern diamond-back rattlesnakes have been reported in many other species. Providing appropriate habitat may be part of the solution. Many keepers report success with defensive individuals if hiding places are provided. To our knowledge, experimental tests have not been performed, and we see here an excellent example of the interface between behavioral research and the development of good husbandry techniques.

Behaviors guided by tactile cues

Tactile cues are important contributors to social and reproductive behaviors. Although chemical cues usually guide males to females, once the individuals meet, tactile information comes into play. If several males are simultaneously attracted to the same female, male combat is likely in some species. The winner is the male that eventually mates with the female. In some species, many males are present simultaneously, all competing for one female. This process is called "scramble competition" rather than male combat and leads to formation of the famous mating balls, which can contain dozens or even hundreds of males. Garter snakes (T. sirtalis) in some parts of their range form such balls.

Less chaotic mating arrangements are more common, a few males courting one female. In this circumstance, ritualized combat is likely to occur, as in some rattlesnake species. Two males engage each other in a pushing contest involving the anterior parts of their bodies, which usually are raised off the ground, each male pressing against the other. The winner is able to press his opponent down to the ground and hold him there for a few seconds or longer. Losers of such contests typically retreat and are sexually refractory for days afterward. Although the contest requires effort, it seems most unlikely that physical exhaustion can be the explanation for the loser's withdrawal and refractoriness. Instead, a neuroendocrine mechanism must exist by which losing suppresses subsequent aggressive and sexual activities, at least temporarily. This mechanism may benefit both winner and loser in that the winner mates with no further distraction and the loser manages to avoid serious damage. An interesting characteristic of male combat among vipers is that males usually do not bite each other during the ritualized wrestling activity. Because the snakes are not immune to their venom, the vipers could inflict serious damage through fang punctures and venom injection. By replacing such actions with ritualized wrestling, both males benefit. By withdrawing after defeat, the loser spares himself further domination as well as, perhaps, a biting attack by the winner.

Species in which male combat occurs typically exhibit sexual dimorphism in body size, males being larger than females. The idea is that combat creates a selective pressure favoring large males, because size correlates with winning versus losing. On the other hand, females should generally be selected for large body size because this factor determines clutch size. Within the limits of opposing selective pressures, females should generally be large. Males also are large, even larger than females, if male combat is important for mating success. If male combat does not occur in a species, males are smaller than females. These generalizations appear to hold over a broad range of species.

Sexual dimorphism in size is relatively common among reptiles, as is sexual dichromatism. In dichromatic species, males usually are more brightly colored than are females, a fact that correlates with the males' need to defend and advertise territories and to attract females. There are some spectacular cases among the spiny lizards (genus Sceloporus) in which both males and females have brilliant (but different) color patterns. These cases are not well understood, but they constitute an extreme form of dichromatism in which both sexes may be sacrificing crypsis to communicate sexual identity. It is possible, however, that future research will reveal that one or both of these patterns, although perceived as brilliant and conspicuous to human observers of preserved specimens, are nevertheless cryptic in the natural habitat.

Because male combat is a form of tactile stimulation, (1) delivery of this stimulation has become highly ritualized in some snakes and lizards, (2) the "meaning" of the stimulation appears to depend on differential neuroendocrine events in winners and losers, (3) delivery of the stimulation appears to inhibit tissue-damaging bites, at least for a while (it is possible that escalated aggression, including bites, could occur if the loser fails to retire), and (4) this form of tactile stimulation has created a selective pressure favoring large body size and increased ability to deliver the tactile information. Females benefit when they mate with males who have won combat encounters and are, by this measure, superior males. Sons of such males are presumed to inherit the size and strength of their fathers. Daughters also may benefit from genes favoring

large size. Although females can benefit by doing nothing, that is, by simply letting males fight and then mate with the winner, it has been reported that females sometimes add an element of their own. Females of several pitviper species raise their heads above the ground when a male approaches. This is the same behavior that combating males use at the start of their contests. The female may be making an aggressive gesture that has the effect of differentiating dominant and subordinate males. Males that have recently lost in combat are intimidated by this action on the part of a female, whereas males who have recently won in combat are not intimidated and proceed with courtship. Females can easily discriminate these two types of males on the basis of the males' behavior immediately after the female presents a combat intention display. This is the hypothesis currently held by a number of herpetologists who study the reproductive behavior of vipers.

Courtship and copulation in nonvenomous species have been studied in detail, and a useful terminology has been developed. Precourtship behaviors are those by which the potentially large distances between male and female are reduced. These behaviors usually involve the following of female pheromone trails by males. In some species, males may also use a head-raised posture to search for visual cues arising from females. An important role of visual cues has been established for ratsnakes (genus Elaphe) and is believed to exist in other genera as well. Males are attracted by the visual cues, and when the male is relatively near the female, chemical cues become readily available regarding the female's specific and sexual identity and her state of sexual readiness.

On making contact with a receptive conspecific female, the male initiates a series of behaviors typically grouped into three phases: tactile-chase, tactile-alignment, and intromission and coitus. At first the male exhibits a high rate of tongue flicking, during which he is apparently confirming the information he has previously obtained during the trail-following period. Direct contact with sexual pheromone along the female's dorsal surface likely intensifies the male's sexual motivation, leading him to rub his chin in a linear series of jerky movements along the female's back. A female might flee at this point, and the male usually follows, sometimes attempting to mount the female. This tactile-chase phase continues until the female remains stationary and allows the male to mount along part or all of her dorsum. The most conspicuous act usually is chin rubbing by the male along the female's back, advancing toward her anterior, moving posterior, and starting forward again. In the family Boidae, in which males have vestigial pelvic structures in the form of spurs, the tactile-chase phase of courtship entails spurring, which is rapid, oscillating movements of the spurs against the female's body. In some species of rattlesnakes, the male curls his tail around the base of the female's tail and gently massages her by moving his curl over the female's vent and down the length of her tail while repeatedly rubbing his chin along her dorsal, anterior surface. These behaviors may be analogous to the titillation movements by which male pond turtles stroke the heads and necks of their mates with long fore claws.

The tactile-alignment phase contains all of the foregoing behaviors and the juxtaposition of cloacal apertures, a posture that eventually allows copulation. The male and female achieve this important posture entirely with tactile sensation; there is no visual guidance. (Although there is ample evidence of integumentary tactile receptors in snakes and other reptiles, the term "hedonic receptors" is rare or absent in the herpetological literature. This term and various synonyms occur commonly in the mammalian literature, especially the literature on human sexuality, and we suspect it is applicable to the receptors mediating these cloacal alignments during sexual encounters between squamates.) On attaining juxtaposition of the cloacal apertures, the female may exhibit cloacal gaping, and the male may evert one of his hemipenes. At this point, tail-search copulatory attempts occur in which the tails of the partners are engaging each other but the animals' heads are not (i.e., the eyes and other anterior sense organs are not involved). Male garter snakes have been observed to rub their chins on one female while aligning with the cloaca of another female.

Coupling is the eventual outcome of tail-search copulatory attempts. In some colubrid genera, such as Elaphe, Lampropeltis, and Pituophis, it is common for a male to obtain a mouth grip on a female's neck just before penetration and to maintain this grip during coitus. This is a regular feature of mating among lizards (most of the terminology developed by snake researchers can be applied to lizards). One of the most interesting aspects of snake reproduction has to do with the duration of coitus, which ranges from a few minutes in many species to well over 20 hours in others (e.g., vipers and pitvipers). In garter snakes of several species (T. sirtalis, T. sauritus, T. butleri, and probably others), coitus is relatively brief, but a mucoprotein plug forms thereafter in the cloaca of the female that blocks penetration of the female by other males. In vipers and pitvipers, the tendency of the male to remain coupled for extended periods accomplishes the same result as the copulatory plug in garter snakes. On the other hand, the male garter snake is free within 15–30 minutes to seek additional copulation, whereas male vipers and pitvipers are unable to do so for 20–30 hours. Such variation may be associated with several ecological factors, such as the availability of sexually receptive females nearby. If availability is high, it makes sense to uncouple quickly and for the male to initiate courtship with new females. If, however, females are widely spaced and it is likely that several males will be simultaneously attracted to each receptive female, a successful male may benefit more by guarding the inseminated female than by leaving her while he goes on an uncertain hunt for a new female. The density of predators that might take advantage of snakes in copula is another ecological factor that could influence the duration of coitus. A high density of predators leads to selection for brief copulations. These ecological factors have not yet been studied systematically by herpetologists.

Maternal behavior

Little or no interaction occurs between male and female after coitus. With rare exception (male western diamondback rattlesnakes have been observed to remain with females for some days before and after copulation), there have been no scientific reports of long-term pair bonds between males and females in any species of reptile. Females of some species exhibit maternal behavior. Building of nests with attendance of eggs has been reported among king cobras (Ophiophagus hannah), Great Plains skinks (Eumeces obsoletus), and most crocodilians. Female turtles deposit their eggs in nests, sometimes with elaborate digging and refilling, but no species has been reported to attend the eggs or nest after oviposition and refilling of the nest cavity. Indian pythons (Python molurus) have been observed to brood their eggs using shivering movements to generate heat. Although parental (maternal) care of neonates is now well known among crocodilians, early reports of this behavior were doubted until modern researchers developed methods to observe these animals, especially American alligators (Alligator mississippiensis) in captivity as well as in the wild. The well-organized maternal behavior of crocodilians, the last of the ruling reptiles, has prompted some paleontologists to speculate about the presence of maternal care in dinosaurs. This topic remains controversial but is gradually being supported by an impressive array of fossil evidence and insightful argument.

New evidence regarding maternal behavior is likely to arise from the study of certain viviparous snakes. Several investigators have reported that female rattlesnakes remain with or very near their litters for several days after parturition. Initially this behavior was considered unimportant, perhaps the result of maternal exhaustion from the act of giving birth. Now it has been hypothesized that maternal attendance of neonates may be more than an artifact of exhaustion. Perhaps the fitness of the neonates is enhanced by the mother's presence, and this means her fitness may be enhanced. The general idea is that the mother's presence may discourage predators who would otherwise take a toll on the neonates. The mother's presence also may allow the neonates to become familiar with her odors and use them to find their way to the hibernaculum. That is, the neonates might locate the den by trailing familiar odors deposited by the mother. None of these ideas has been subjected to rigorous scientific testing, but such tests are likely to be performed.

Activity patterns and thermoregulation

Activity patterns influenced by seasonal, daily, or other rhythms probably have been the targets of more herpetological research than any other aspect of behavior except diet. This is partly a consequence of the development of miniaturized radiotelemetric equipment and partly the result of the simple fact that understanding any animal requires a sense of the actions it performs and when it performs them. Numerous investigators are interested in energy budgets and related phenomena, and activity patterns tell us about most of the energy costs sustained by animals. Feeding success tells us about energy gains. The construction of activity budgets is an important step in the calculation of energy budgets. Many herpetologists consider the study of activity patterns a necessary starting point, once the basic questions of taxonomic allocation are at least tentatively answered. It could be hypothesized that we could predict activity patterns and energy expenditures if we knew the resource needs of a species and the distribution of these resources in the habitat. Although this reasoning is sound, rarely do we know about all the resource needs of a species, and we know even less about their distribution, especially in the perception of the animals. Knowledge of resource needs is an important goal, but instead of using the information to predict activity patterns, we frequently use data on the patterns to infer resource needs and distributions.

The longest migration by any reptile is the oviposition movement of some female green seaturtles (Chelonia mydas) from their feeding grounds in the kelp forests off the coast of Brazil to the beaches of Ascension Island in the South Atlantic, about midway between Brazil and the west coast of Africa (approximately 1,600 mi [1,900 km] from Brazil). Other populations of green seaturtles and all other seaturtles make substantial annual movements to nesting beaches, although none of these migrations is as long as the swims of the subpopulation of green seaturtles using Ascension Island. The sensory basis of this remarkable migration involves geomagnetic sensitivity, chemical cues, and probably celestial cues. Even more remarkable is the movement of hatchlings from Ascension Island to the Sargasso Sea and later to the Brazil kelp beds, the turtles again using the same variety of sensory systems. Somewhat less spectacular migrations are known in other reptiles, especially snakes in temperate zones, where hibernation sites and feeding sites are separated by distances on the order of 1–7 mi (1.6–11.2 km). The snakes make an annual vernal migration to the feeding grounds and an autumnal migration back to the hibernacula. Sensory bases for these movements have not been studied sufficiently, but it seems clear that chemical cues are involved, and there is reason to suspect a role for geomagnetic, celestial (especially solar), and visible landmark cues.

Homing has been observed in a variety of reptiles that have returned to sites from which they were experimentally displaced. Alligators, several species of snakes and turtles, and a few species of lizards have been studied, but we know relatively little about the sensory basis of this behavior. Geo-magnetic cues were probably used by the alligators, chemical cues were certainly involved in several of the turtle studies, and solar cues were well documented in several of the snake studies. In most other cases, however, our knowledge has not advanced beyond the fact that homing or related behavior (e.g., y-axis orientation) occurred. Some studies have shown no evidence of return to a site occupied before displacement. This lack of evidence gives rise to interesting speculation that the motivation to return depends on the quality of the initial habitat and the quality of the habitat in which the test animals were released. An important implication is that the animals assess their habitats and use this information to decide whether to move toward "home" or to adopt a new home for themselves. If such behaviors occur, the cognitive mechanisms involved in habitat assessment will prove to be even more interesting than the sensory mechanisms mediating orientation and movement toward home. The literature on reptile homing behavior contains many anecdotes that have substantially influenced our collective thinking. For example, rattlesnakes have been removed from a human property (usually a backyard, field, or a common area in a community) and released a distance away (usually on the order of a mile or two [1.6–3.2 km]) only to return to its initial location within a few days. Another interesting case involved a black ratsnake (Elaphe obsoleta) removed from a farm several times but always returning within a few days. In cases of this sort, the snakes were not marked at the time of original capture, so it is not absolutely certain that the returning snake and the removed snake were one and the same. On the basis of size, coloration, and unique features such as scars, we can be reasonably confident, but the following case, described by the late Charles M. Bogert, urges caution.

Bogert was collecting reptiles in New Mexico and caught a striped whipsnake (Masticophis taeniatus) in a particular bush, which Bogert marked with a golf tee. The next day, while passing the same bush, Bogert caught a second striped whipsnake in it. Later on the second day, Bogert visited the bush again, and, sure enough, a third specimen of the species presented itself. There is no question that the snakes were three different individuals because Bogert caught and preserved each one. He was interested in what might have been special about the bush, but he was able to identify nothing. Perhaps this was pure chance, always a possibility with anecdotes. On the other hand, maybe the bush was in a prey-rich area or in a migration path or in a spot containing an ideal refuge from the sun or from predators. If any of these conditions existed, it would not be surprising that removal of an initial occupant might be followed by the arrival of another. If the first occupant had not been captured and kept out of the habitat, we might easily misinterpret the second and third snakes as being the initial one. Although anecdotal reports of homing should not be discounted, they should be regarded cautiously.

Closely related to homing is territoriality, the defense of a resource, usually in a particular place but sometimes mobile, as in the case of potential mates that might move a considerable distance but are nevertheless defended in each place they occupy. Numerous lizards exhibit unambiguous territoriality, defending feeding areas from conspecifics and sometimes from heterospecifics that compete for the same foods. Clever experiments have shown that adding food to territories results in shrinkage of the area defended, whereas depleting food from territories results in expansion of the area defended. Results of such studies leave no doubt that the territorial behavior of the resident lizard is sensitive to the quantity and quality of the food contained within the territory. The results of the studies also leave no doubt that the lizards assessed their food supplies and responded accordingly. Food, however, is not the only resource that lizards defend. Oviposition sites are important in some species, and refuge is important in others.

Crocodilians are known to behave in a territorial manner, especially mature females who defend their nests. Large males also appear to be territorial, particularly during the breeding season. Turtles and snakes present a far more ambiguous situation, except for the few species in which females attend their eggs or young. Even these cases are not clear examples of territoriality, because there is no evidence that the females defend their eggs or oviposition sites against conspecifics. It is possible that mothers defend their eggs or neonates only against heterospecific oviphages or predators, in which case the term territoriality may not be appropriate. Territoriality implies intraspecific interaction. At present we cannot state with certainty that any species of turtle or snake exhibits true territorial behavior. Anecdotal evidence exists for both groups, and behavioral phenomena among captive specimens also are suggestive. The possibility of territoriality among these reptiles should be considered, but caution should be exercised in interpretation of anecdotal evidence.

Another approach to the study of activity patterns of reptiles is to record the number of individuals seen or captured (usually in pitfall traps) during each month of the year. In temperate North America, such projects reveal several annual patterns: a single peak during the warmest months with sharply reduced activity before or after; a single peak during the warmest months but fairly broad activity period such that substantial numbers of individuals are active before and after the warmest months; and two peaks, one in spring and one in autumn. Some species, such as garter snakes, appear to remain active all year if the temperature remains high enough. Other species appear to be endogenously programmed to become inactive during winter months, even if the temperature is artificially elevated. Having maintained many rattlesnakes in captivity, we have found that in species such as the prairie rattlesnake and the western diamondback, some individuals remain active all year if the temperature is kept at 79°F (26°C) or higher. Other individuals "shut down" for several months under the same conditions, refusing food for one to three months each year.

Closely associated with the circannual studies of reptile activity are parallel studies of reproduction. Periods of high activity or capture success can correspond with periods of intense feeding behavior, but they can also correspond with periods of courtship and copulation, particularly because of the likelihood of capturing males active in searching for reproductively motivated females. Pregnant female prairie rattlesnakes, for example, are relatively inactive, perhaps even congregating in birthing rookeries, whereas nonpregnant females have made a vernal migration to hunting grounds. The females that migrate are the ones likely to develop ripe ova and to become sexually motivated. Consequently, they are the ones mature males pursue, making themselves vulnerable to traps or to capture by hand. Although a number of reproductive strategies are observed across the various families of reptiles, most of these strategies involve seasonally increased activity by one sex or the other. It is safe to conclude that circannual activity patterns are partly correlated with ovarian and testicular cycles or with courtship and copulatory seasons in taxa that exhibit a dissociation between reproductive behavior and genital physiology (i.e., some species breed at times of the year different from the times gametes are produced; in such cases, activity is influenced by the breeding season rather than the gamete-producing season).

In addition to circannual studies of reptile activity, there have been many studies of circadian rhythms, that is, changes in activity during the 24-hour period of a typical day in the animal's active season. Some species are strictly diurnal (active only during daylight), others are strictly nocturnal (active only at night), and other species are crepuscular (active at dawn and dusk). Juvenile kingsnakes (Lampropeltis getula floridana) exhibit crepuscular and nocturnal patterns, whereas adults are diurnal. The shift toward diurnal behavior occurs when the snakes are approximately 35 in (90 cm) snout-vent length and capable of defending themselves against a variety of predators, particularly birds, that are active during daylight. Nocturnal reptiles exhibit relative cessation of activity during periods of full moon, when ambient illumination at night favors detection by predators.

In some species, daily activity patterns shift with average daily temperature. Among plains garter snakes (Thamnophis radix) and western diamondback rattlesnakes, individuals are diurnal at the relatively low temperatures of early spring and late autumn, but during the hottest days of summer, these same individuals become nocturnal. During intermediate parts of the year, such as late spring and early summer, the snakes are crepuscular, because it is too hot during the day and too cold at night. For species with very broad geographical ranges, it is possible that individuals in northern latitudes are diurnal whereas individuals to the south are crepuscular or nocturnal, depending on thermal conditions.

Temperature is a primary modulator of many physiological processes influencing digestion, reproduction, and locomotion in reptiles. Herpetologists have focused on this factor more than any other. Each species has a lethal minimum and maximum temperature, below or above which life ceases immediately. Within this range, which might be 17.6–104°F (−8°C to +40°C), there is a second range from the critical thermal minimum (CT_Min) to the critical thermal maximum (CT_Max), which might be from 35.6°F to 89.6°F (2°C to 32°C). Survival below the CT_Min or above the CT_Max is possible for brief periods, longer below CT_Minthan above CT_Max, but death occurs relatively rapidly as the temperature converges with the respective lethal extremes. Yet another range is nested with the boundaries of CT_Minto CT_Max. This range runs from the voluntary minimum to the voluntary maximum, within which the reptile prefers to remain when choice (i.e., behavioral thermoregulation) is possible. This range defines the animal's normal or preferred activity range, and its midpoint corresponds to the animal's voluntary or preferential mean temperature. The precise temperatures corresponding to these boundaries shift during the course of the year, a phenomenon called acclimation. For example, in early spring, a reptile might prefer to keep its body temperature between 64°F and 82°F (18°C and 28°C), but later in the summer, the voluntary minimum and maximum might shift to 68°F (20°C) and 86°F (30°C), respectively. As this acclimation effect occurs, the lethal minimum, CT_Min, lethal maximum, and CT_Max all shift upward by 3.6–5.4°F (2–3°C).

One of the dominating necessities of any reptile is to keep its body temperature within the preferred range of its species. Because all extant reptiles are ectotherms, temperature regulation involves a large suite of behaviors, some obvious and some remarkably subtle. Reptiles also exhibit many anatomical and physiological adaptations. Among the more obvious thermoregulatory behaviors are locomotory activities by which the animals shuttle between sunlight and shade as necessary to keep their body temperatures within the optimal range. Basking is another behavior by which body surfaces are exposed to sunlight to increase core body temperature. Reptiles of some species can thermoregulate by altering the amount of surface area exposed to sunlight. They do so with inconspicuous alterations of posture, sometimes associated with color change. Large snakes are known to retain fecal material and to use it for storing heat. If a snake needs to reduce its heat load, one option is to eliminate the feces. Coiling the body and aggregating with other snakes can profoundly reduce the rate of heat loss, such that snakes in winter dens can have higher body temperature than would be indicated by the ambient climate. Because of the many behavioral and other devices they have for regulating body temperature, reptiles can maintain their temperatures within a surprisingly narrow range. The typical standard error of the mean of repeated measurements of an individual reptile's preferred body temperature is less than 1.8°F (1°C). These measurements were made under close to ideal conditions; nevertheless, such studies show how precise reptiles can be when heat sources and refuge are readily available and when no obstructions are placed in the way of locomotion. Although reptiles lack the endothermic mechanisms of birds and mammals and only a few species of reptiles engage in shivering thermogenesis, when solar or other heat sources are available during the active season, many reptiles can maintain high body temperatures with surprisingly little variability.

The temperature at which reptiles maintain their bodies during the active season can be influenced not only by acclimation but also by disease. Infection with pathogenic bacteria can cause the reptile to prefer a higher than usual temperature. This so-called behavioral fever kills the bacteria within a few days. This interesting phenomenon has been found to occur among most ectothermic vertebrates and is straightforwardly analogous to the endogenous fever response of endothermic vertebrates to pathogenic bacteria. Another thermal phenomenon is emotional fever. Lizards handled briefly by humans regulate their body temperature between one and two degrees higher than normal. This elevation may be related to a flight or escape response or to a metabolic response to the immunosuppressive effects of stress. The presence of food in the stomach also induces reptiles to elevate their body temperature and digest the food more rapidly and more thoroughly than would otherwise be the case. Pregnant females prefer higher temperatures, which facilitate gestation. As we discover these fascinating events, our appreciation of the precision of reptile behavior increases, as does our ability to care for these animals in captivity.

Resources

Books

Burghardt, G. M. "Behavioral and Stimulus Correlates of Vomeronasal Functioning in Reptiles: Feeding, Grouping, Sex and Tongue Use." In Chemical Signals: Vertebrates and Aquatic Invertebrates, edited by D. Muller-Schwarze and R. M. Silverstein. New York: Plenum Press, 1980.

Gans, C., and F. H. Pough, eds. Biology of the Reptilia. New York: Academic Press, 1977.

Halpern, M. "Nasal Chemical Senses in Reptiles: Structure and Function." In Biology of the Reptilia, Vol. 18, edited by C. Gans and D. Crews. Chicago: University of Chicago Press, 1992.

Hayes, W. K., I. I. Kaiser, and D. Duvall. "The Mass of Venom Expended by Prairie Rattlesnakes When Feeding on Rodent Prey." In Biology of the Pit Vipers, edited by J. A. Campbell and E. D. Brodier. Tyler, TX: Selva, 1992.

Seigel, R. A., J. T. Collins, and S. S. Novak, eds. Snakes: Ecology and Evolutionary Biology. New York: McGraw-Hill, 1987.

Periodicals

Aleksiuk, M. "Temperature Dependent Shifts in the Metabolism of a Cool Temperate Reptile, Thamnophis sirtalis parietalis." Comparative Biochemistry and Physiology 39A (1971): 495–503.

Andren, C. "The Role of the Vomeronasal Organs in the Reproductive Behavior of the Adder Vipera berus." Copeia 1982, no. 1: 148–157.

Bennett, A. F. "The Thermal Dependence of Lizard Behavior." Animal Behavior 28 (1980): 752–762.

Brattstrom, B. H. "The Evolution of Reptilian Social Behavior." American Zoologist 14 (1974): 35–49.

Brown, W. S., and F. M. MacLean. "Conspecific Scent-trailing by Newborn Timber Rattlesnakes, Crotalus horridus." Herpetologica 39 (1983): 430–436.

Carpenter, C. C. "Communication and Displays of Snakes." American Zoologist 17 (1977): 217–223.

Chiszar, D., A. Walters, J. Urbaniak, H. M. Smith, and S. P. Mackessy. "Discrimination between Envenomated and Nonenvenomated Prey by Western Diamondback Rattlesnakes (Crotalus atrox): Chemosensory Consequences of Venom." Copeia 1999, no. 3: 640–648.

Cooper, W. E., Jr. "Correlated Evolution of Prey Discrimination with Foraging, Lingual Morphology, and Vomeronasal Chemoreceptor Abundance in Lizards." Behavioral Ecology and Sociobiology 41 (1997): 257–265.

Devine, M. C. "Copulatory Plugs, Restricted Mating Opportunities and Reproductive Competition among Male Garter Snakes." Nature 267 (1977): 345–346.

Dill, C. D. "Reptilian Core Temperatures: Variation within a Individuals." Copeia 1972, no. 3: 577–579.

Duvall, D., K. M. Scudder, and D. Chiszar. "Rattlesnake Predatory Behaviour: Mediation of Prey Discrimination and Release of Swallowing by Cues Arising from Envenomated Mice." Animal Behavior 28 (1980): 674–683.

Ford, N. B., and J. R. Low. "Sex Pheromone Source Location by Garter Snakes: A Mechanism for Detection of Direction in Nonvolatile Trails." Journal of Chemical Ecology 10 (1984): 1193–1199.

Garstka, W. R., and D. Crews. "Female Sex Pheromones in the Skin and Circulation of a Garter Snake." Science 214 (1981): 681–683.

Gillingham, J. C. "Reproductive Behavior of the Rat Snakes of Eastern North America, Genus Elaphe." Copeia 1979, no. 2: 319–331.

Greene, H. W. "Dietary Correlates of the Origin and Radiation of Snakes." American Zoologist 23 (1983): 431–441.

Hirth, H. F., and A. C. King. "Body Temperatures of Snakes in Different Seasons." Journal of Herpetology 3 (1969): 101–102.

Kardong, K. V. "The Strike Behavior of the Rattlesnake, Crotalus viridis oreganus." Journal of Comparative Psychology 3 (1986): 314–324.

Krysko, K. L. "Seasonal Activity of the Florida Kingsnake, Lampropeltis getula floridana (Serpentes: Colubridae), in Southern Florida." American Midland Naturalist 148 (2002): 102–114.

Lowe, C. H., P. J. Lardner, and E. A. Halpern. "Supercooling in Reptiles and Other Vertebrates." Comparative Biochemistry and Physiology 39A (1971): 125–135.

Mackessy, S. P. "Venom Ontogeny in the Pacific Rattlesnakes, Crotalus viridis helleri and C. v. oreganus." Copeia 1988, no. 1: 92–101.

Naulleau, G. "The Effects of Temperature on Digestion in Vipera aspis." Journal of Herpetology 17 (1983): 166–170.

Reinert, H. K., D. Cundall, and L. M. Bushar. "Foraging Behavior of the Timber Rattlesnake, Crotalus horridus." Copeia 1984, no. 4: 976–981.

Rodda, G. H. "The Orientation and Navigation of Juvenile Alligators: Evidence of Magnetic Sensitivity." Journal of Comparative Physiology A 154 (1984): 649–658.

Semlitsch, R. D., K. L. Brown, and J. P. Caldwell. "Habitat Utilization, Seasonal Activity, and Population Size Structure of the Southeastern Crowned Snake, Tantilla coronata." Herpetologica 37 (1981): 40–46.

Shine, R. "Sexual Size Dimorphism and Male Combat in Snakes." Oecologia 33 (1978): 269–277.

Shine, R., and J. Covacevich. "Ecology of Highly Venomous Snakes: The Australian Genus Oxyuranus (Elapidae)." Journal of Herpetology 17 (1983): 60–69.

Yamagishi, M. "Observations on the Nocturnal Activity of the Habu with Special Reference to the Intensity of Illumination." The Snake 6 (1974): 37–43.

York, D. "The Combat Ritual of the Malayan Pit Viper (Calloselasma rhodostoma)." Copeia 1984, no. 3: 770–772.

David Chiszar, PhD

Hobart M. Smith, PhD

BEHAVIOR

Americans for years have been embracing new technology to make life more convenient, and at the same time grew accustomed to cheap, abundant energy to power that technology. Each year more than $500 billion is spent in the United States for energy to perform work and provide heat, and the energy needed for creating and building businesses, home-making, getting around, purchasing goods, and seeking pleasure. The decision-making exhibited while engaging in these daily activities varies widely, which results in diverse energy use behavior.

THE LONG-TERM IMPACTS OF DECISIONS

Energy-use behavior cannot be looked at just in the here and now or in isolation. Americans developed a greater reliance on heat, light, and power than any other nation, primarily due to decisions made by industry, government, and individuals of earlier generations that largely established the patterns for behavior today. Collective choices made long ago have behavioral consequences today, just as collective choices made today will have behavioral consequences for many more years to come.

The high-energy-consumption culture evolved primarily as the automobile became affordable in the 1920s and 1930s, offering tremendous mobility and the possibility of distancing home from work, school, and pleasure. It was then accelerated by the post-World War II federal policies of funding a vast network of highways and offering subsidies (home mortgage and property tax deductions) to make home ownership more affordable. Government policymakers at the time never realized the energy consequence of these nonenergy policies. Highways to everywhere, and home ownership subsidies promoted flight from city centers to suburbia and a high-energy-consumption economy largely based on the automobile. With these policies in place, the energy use patterns established a trend of greater and greater consumption. Moreover, the many benefactors of these policies amassed significant power and influence in the political system, discouraging any reversal.

Another factor contributing to high-consumption behavior is the ever-growing affluence of the population. In the 1950s, U.S. consumers spent around 25 percent of disposable income for food, which fell to less than 10 percent by the 1990s. For many, this translates into less than three hours of wages to cover the family's weekly food bill. (For much of the developing world, it can take seven or eight hours of wages to feed a family of four for one day.) Moreover, six or seven hours of wages in the United States can cover the cost of a month's worth of gasoline for the cars, and electricity and natural gas for the home.

This growing affluence allows a greater percentage of disposable income to go toward purchases of energy-using technology and ever-more-elective applications, rather than the cost of energy to power the technology. For example, while energy costs had remained flat or risen only slightly from 1980 through 2000, the average cost of an automobile tripled, going from around $7,000 to $21,000. Furthermore, as the United States became more affluent, the distinction between want and need—elective and essential—has blurred. Technology that was rare or nonexistent in the 1960s became a want in the 1970s and 1980s, and evolved into what many consider a need or necessity in the 1990s. Most households are now dependent on all sorts of energy-hungry technology that did not even exist in the 1960s—appliances such as lawn trimmers, personal computers, and microwave ovens, to name a few. Greater affluence, and an economy geared toward high consumption, has resulted in U.S. per capita energy use growing to more than thirty times that of developing world nations, and more than twice that of Western Europe or Japan.

One of the biggest fears with massive consumption and the high energy lifestyle is the high level of immigration that has accompanied it. Although the U.S. birthrate has been slightly more than self-sustaining since the 1970s, a liberal immigration policy had added more than 30 million people to the population by 1995, and is likely to push the population to more than 400 million by 2050. Millions of people from around the world try to immigrate, legally or illegally, to enjoy the freedom and the opportunities of the United States. Because most immigrants, regardless of culture and country of origin, tend to quickly assume the U.S. norm of high-energy-use behavior that increases carbon emissions, exacerbates air pollution (through a need for more power plants and automobile use), and worsens the dependence on imported crude oil, overpopulation and poverty is as much a United States problem as a world problem.

LIFESTYLES AND ENERGY USE

Energy is the ability to do work. The work can be done by man or machine; the fuel to do the work can come from food or fuel. Humans often have a choice of whether or not to continue to develop technology that replaces the work of man as well as do other types of work that man is not capable of doing. Historically, the choice has been almost always to embrace technology, driving the steady increase in demand for energy.

There is often a mental disconnect between technology and the energy needed to make technology work. Except for a small percentage of the population, people are not much interested in energy itself, but only what it can do for them. That is because energy is largely invisible. The units of energy—a kilowatt hour of electricity or a cubic foot of natural gas—cannot be seen. Thus, energy is primarily thought of in financial terms: the dollar amount of the electric or natural gas bill, or the cost of refueling the car.

Energy behavior can be categorized loosely as conserving (frugal), efficient, or high-energy (Table 1). It is not always fair to make such clear-cut distinctions because many behavior patterns exist within each income level that are beyond easy classification. For example, a few cross-classifications could be rich and frugal, rich and efficient, poor and frugal, and poor and wasteful. Ironically, the poor are often the most wasteful and inefficient because they own older cars and live in leaky homes.

The distinction between high-use versus conserving or efficient is well-known, but the difference between energy-conserving behavior and energy-efficient behavior is a more subtle distinction. Energy is used to perform important tasks such as getting to work. A vehicle will use a given amount of British thermal units (Btus) per mile. Multiplying the Btus per mile by the number of miles traveled, results in the total Btus used. The goal of energy conservation is to reduce the number of Btus used. Energy-conserving behavior is not strictly about forgoing consumption. The conserving person still needs to get to work; he just wants to get there by using less energy, say, by substituting the train, bus or carpool for driving alone. On a per passenger basis, the difference between the two could be 100 to 160 miles per gallon (mpg) for carpooling or mass transit, compared to 15 to 40 mpg for driving alone. Remembering to turn off the lights when leaving a room, or turning down the thermostat to 60°F, or shoveling the walk instead of buying a snow blower, are other examples of energy-conserving behavior.

Energy-efficient behavior usually involves embracing all technology to do work, but picking the most energy-efficient products to do that work. The energy-efficient choice is to stay in the single passenger automobile, but reduce the Btus per mile by buying an efficient model that gets 40 mpg rather than

one that gets 15 mpg, or replace a 75-watt incandescent light bulb with a 25 watt fluorescent tube. The amount of illumination is the same, but the amount of energy used is one-third less. In terms of total energy savings to a nation, energy conservation is more important than energy efficiency since there is less energy used when no light is on than when an efficient one is on.

A person exhibiting energy-conserving behavior is likely to exhibit energy-efficient behavior as well, but someone who exhibits energy-efficient behavior is not necessarily going to be into energy conservation. Energy conservation usually indicates a sacrifice in something, be it safety, aesthetics, comfort, convenience, or performance. To many energy-efficient people, this is an unacceptable compromise. Energy-efficient homeowners will take energy efficiency into account in making decisions about home lighting; yet, if they have a strong preference for art gallery quality lighting, they do not hesitate to spend more for electricity than a conserving neighbor whose only concern is a good reading light. Whereas energy-efficient behavior primarily entails an approach to making technology-buying decisions energy-conservation habits require a full-time, conscious effort to reduce the amount of technology used.

DECISION-MAKING THEORY

The reasons for the range of energy-use lifestyles, and the motivation behind energy decision-making, are varied and complex. Prior to the 1970s, there was little study of energy-use behavior. But energy scarcities and the growth of the environmental movement made the energy problem a social problem that economists, psychologists, sociologists, and anthropologists all began to address.

Economists primarily look at energy decisionmaking, like all other decision-making, as a function of price and utility: The individual is a rational utility maximizer who gathers and weighs all the relevant information to make cost-benefit evaluations to arrive at decisions. If an energy conservation or efficiency product proves beneficial, the purchase will be made. It is uncertain how much of the population realizes that often the greater initial out-of-pocket cost for energy-conservation measures and energy-efficient products will be made up by greater savings through the lifetime of the product. And even when aware of the life-cycle savings, the purchase of more energy-efficient products may be rejected because of an unacceptable compromise in safety, aesthetics, comfort, convenience, quality, or performance. For example, the five-passenger Mercedes might be preferred over the five-passenger Hyundai since the Hyundai's acceleration, reliability, and luxury shortcomings more than outweigh the benefits of its lower price and better fuel economy.

The current price of energy is a primary factor entering into decision-making, yet the expected future price of energy can be even more important since the product life cycles of most technology is over ten years (autos and appliances 14 or more years, real estate 30 or more years). After the Energy Crisis of 1973, people adopted energy-conserving and efficient behavior more because of the fear of where energy prices were headed than the price at that time. Almost all energy forecasters in the 1970s and early 1980s predicted that energy prices would soar and oil resources would soon disappear. National Geographic in 1981 predicted an increase to $80 per barrel by 1985—a quadrupling of gasoline prices. By the 1990s, when these forecasts turned out to be wildly erroneous, most people reverted back to their old lifestyles, and became much more skeptical of any proclaimed impending crisis.

Whereas the focus of economists is on price and utility, the focus of psychologists has been on attitudes and social norms. For example, the nonprice reasons for choosing an energy-conserving or efficient lifestyle have been for social conformity and compliance—a sense of patriotism, good citizenship, or because it was the environmentally friendly thing to do. The main theory is that attitudes determine behavior, and if attitudes can be changed, it is more likely that behavior will change too. However, there is also the opposite theory: Behavior causes attitudes to change. If persons assume an energy-conserving lifestyle, they will assume attitudes to support that action to avoid internal conflict or hypocrisy (Stern, 1992).

Another problem in studying attitudes and behavior toward energy is the pace of change. Even in times of energy shortage, attitudes and behavior tend to change slowly and are influenced as much by cultural and geographical factors as price. A family living in a 5,000 sq. ft. home can turn down the thermostat, yet still needs to heat a significant amount of space. And if the family lives 75 miles from work, they can switch to a more-fuel-efficient car, yet still must burn considerable gasoline commuting. Of course, this family can make a drastic lifestyle change and consume a fraction of the energy by moving into a 1,200 sq. ft. condominium a few blocks from work and school, but this choice is unlikely for many who have grown accustomed to the comfort, lifestyle and perceived safety of suburban life and feel it is well worth the inconvenience and higher energy costs.

THE COMMERCIAL SECTOR

Energy is a capital investment decision that is often neglected by corporations. When a corporation decides to build or rent office space, the energy needed to heat, air-condition, and illuminate the facility usually is not a top priority. In the 1990s, layout, ergonomics, aesthetics, corporate image, proximity of highways and mass transportation, and other productivity factors ranked much higher. Moreover, there remains skepticism about the ability of energy-efficient technologies and design strategies to simultaneously save energy and improve labor productivity. If the price of energy skyrocketed, lowering energy costs would quickly become a priority again. Many office facilities, not competitive on an energy-efficiency basis, could become obsolete well before their expected lifetime of 50 to 100 years.

THE INDUSTRIAL SECTOR

Lean production—the improvement of processes and operations—is something that all industrial executives encourage, and is largely why the U.S. industrial sector energy consumption dropped about 20 percent from 1973 to 1983. With much of energy efficiency gains already achieved, company executives of the 1990s found the payback from other investments more economically efficient, and consequently have put the emphasis elsewhere. A top priority in the 1990s was faster and cleaner processes that reduced manufacturing costs and reduced waste. If these processes also reduced energy use, it was an added bonus.

Besides operational energy use, corporate decisions have an impact throughout society. One reason that per capita energy consumption in North America is much higher than in the rest of the world was the decision of corporate leaders to expand and relocate away from city centers and to major beltway loops in the suburbs. This necessitated more trucking and a workforce reliant on the private automobile instead of mass transit. In an era of tremendous job insecurity, even the most energy-conserving person is hesitant to reside near work, or live without the mobility of the personal vehicle.

THE TRANSPORTATION SECTOR

Driving by personal vehicle is the most popular mode of transportation. And although there is a desire for a fuel-efficient automobile, fuel efficiency is a consideration well behind style, performance, comfort, durability, reliability, status, and safety. The weak demand for a 40 mpg automobile occurs for several reasons: It is not a status symbol (not stylistic), accelerates too slowly (smaller engine), cramps the driver and occupants (smaller interior), and often offers inadequate protection (too light) in case of an accident.

Another reason for weak demand is that fuel cost in 1999 were a much smaller fraction of the cost of owning and operating a vehicle than it was in 1975. While the average cost of owning and operating an automobile more than tripled from 1975 to 1999, the price of fuel increased only marginally, and average fuel economy improved from 15 to 27 miles per gallon. As fuel cost declines relative to all other costs of operating an automobile, the purchase of a fuel-efficient automobile increasingly becomes a more secondary financial consideration. Most motorists express a preference for greater size, luxury, and performance from the automobiles and trucks purchased, knowing that such attributes usually are detrimental to fuel economy.

The Private Auto Versus Public Transit

The freedom of private transportation is something most Americans have taken for granted and consider a necessity. Only a generation ago, an automobile was considered a luxury, and a generation before that, a rarity. The ascension of the automobile coincided with the decline in mass transit in the 1920s. This trend accelerated after World War II when American society decided to build a vast interstate highway system, emphasizing private automobiles at the expense of mass transit. It is not easy to undo the technological impetus of large infrastructure changes of this nature. According to the U.S. Census Bureau, by 1990, 73 percent of the population drove alone to work, up from 64 percent in 1980. In percentage terms, walking (3.9%), bicycling (0.4%), public transit (5.3%), and carpooling (13.4%) all declined between 1980 and 1990. For other travel (shopping, family business, and leisure), which was responsible for two-thirds of all travel, the share of collective modes and nonmotorized modes was even lower.

A major mass transit handicap is sprawling growth. Mass transit works most effectively in a hub and spoke manner, and the decentralization of urban areas makes it harder and harder to design effective mass transit. This mismatched segregation of home, work, and leisure—particularly in cities such as Houston, Atlanta, and Los Angeles—would require a long time to reverse.

Even where mass transit offers better speed and comparable comfort and convenience, the love of the automobile results in uneconomic decisions affecting energy consumption. For someone driving 30 miles to New York City, tolls, fuel, and parking can easily exceed $20 a day. In comparison, a monthly train pass for the same 30 mile trip runs less than $10 a day. This premium for the privilege of driving is even greater if the yearly $6,000 to $10,000 cost of leasing, insurance, and maintenance is included. Because of congestion, few can claim to drive for speed reasons. The roadway trip often takes more time than via mass transit. Getting more people out of single-passenger cars and into more-energy-efficient mass transit or car pools is going to take more than improving mass transit and the price of gasoline tripling. Americans, like most others in the industrial world, have an emotional attachment to the automobile.

Another reason for choosing the automobile is its development as a mobile office. Cellular phones, laptop computers, and satellite linkups to hand-held communication devices—all of which are getting smaller and smaller—have made it possible to be more productive from the roadways.

Aside from work, the automobile is central for shopping and pleasure. Most people who lived in the suburbs in the 1990s had grown up in the suburbs rather than in central cities. The automobile, and the mobility it affords its owner, is a central aspect of suburban life. Shopping centers and businesses, lured by cheaper land in the exurban areas, do not fear locating away from city centers because Americans show an eagerness to drive greater distances. The auto also caters to the needs of family life. Few suburban parents drive directly to and from work anymore. The growth in extracurricular sports and activities, for parents as well as children, requires the convenience of the automobile.

Higher incomes, higher automobile ownership, and a decline in the population and workplaces that can be served by mass transit has lead to the declining mass transit demand. Criticism of this shift toward the private automobile comes mainly because the individual driver receives the short-term benefits (privacy, comfort, speed, and convenience), while the negative social consequences (air pollution, traffic jams, and resource depletion) are shared by all. Moreover, if people drove less, and drove more-fuel-efficient vehicles, the positive national goal of less dependence on imported oil would be achieved.

Flight

The explosive growth in air travel from 1980 to 2000 occurred because deregulation reduced air fares, disposable incomes rose, and travelers desired to get places faster. People are willing to pay a large premium for speed by flying instead of driving. The premium is largely a reflection of the much greater energy costs of flying, yet it is not always a greater cost. On a passenger-miles-per-gallon basis, usually more energy can be conserved by flying a full aircraft rather than having each passenger drive solo to a given destination.

People make decisions to fly based on speed, the price of the flight, and an airline's on-time arrival. If these factors are the same, then secondary concerns such as comfort become a factor—fewer seats with more spacious seating, and more room to walk about. Since greater comfort means fewer paying passengers, the airlines' decision to cater to the desire for comfort will adversely affect fuel economy per passenger.

The widespread disfavor toward prop planes is another preference adversely affecting fuel economy. Prior to the late 1990s, the 30- to 50-seat plane market was dominated by the more-energy-efficient turboprop planes, yet regional airlines ordered jet engine replacements, citing strong customer preference. Airlines are turning to jets because people want to get places faster. Turboprop planes, which attain near-jet speeds and near-jet performance with less fuel consumption, are noisier and thought to be less safe, even though safety records do not warrant this belief.

The future demand for jet travel is very uncertain. Businesses have traditionally felt a need to travel for face-to-face meetings, but the new communications technology revolution might in the future make business travel less necessary. However, any dropoff in business travel is likely to be replaced by growth in leisure travel as more affluent Americans decide to take more but shorter vacations, and fly for more weekend getaways.

Freight

Individuals and companies make shipping decisions based on price, speed, and reliability. If reliability and speed are equivalent, the decision usually comes down to price. Because energy costs of shipping by air, railway, waterway, and truck vary tremendously, so does the price. Whereas commodities and basic materials are moved by rail, just-intime components and finished product are mainly moved by truck, accounting for over 80 percent of all freight revenue. Rail is cheaper and a much more energy-efficient means to move freight, and has been approaching trucking for speed; yet businesses continue to pay a premium for trucking because rail historically has been less reliable.

THE RESIDENTIAL SECTOR

The American home is widely perceived as a good investment that appreciates. Any additional improvement to the home is considered wise for two reasons: the enjoyment of the improvement, and greater profit when the time comes to sell. This belief, in part, explains the preference for bigger new homes with higher ceilings over the large stock of older, smaller homes built from 1950 to 1970. The average new home grew from 1,500 square feet in 1970 to over 2,200 by 1997, and the inclusion of central air conditioning grew from 34 to 82 percent. These new homes are usually farther from city centers, and indicates a general willingness to endure the inconvenience and higher energy cost of longer commutes. The continuing trend of bigger suburban homes farther from city centers is attributable to the affordable automobile, the expansive highway system, and the pride of owning one's own home. Whereas a generation ago a family of eight felt comfortable sharing 2,000 square feet of living space, the generation of the 1990s located twice as far from work so that they could afford twice the space for a family of four. But home size alone can be a poor indicator of energy use. Energy consumption can often vary by a factor of two or three for similar families living in identical homes (Socolow, 1978).

Many people approach home ownership investments with only two major concerns: how much down and how much a month. They may be tuned into the present energy costs of a new home, but usually give little thought to how much energy will cost 10 or 20 years into the future. If energy-efficient features push up how much down and how much a month beyond what the buyer can afford, buyers must forgo energy-efficient features. However, selecting energy efficient features for a new home does not necessarily have to increase the down payment and monthly mortgage payment.

Aesthetics is often more important than energy efficiency to home buyers. Energy efficiency that is economically efficient is welcomed if it does not come at the expense of aesthetics. Tightening up a home with better insulation and caulking is fine, but solar collectors on the roof are thought by many to be an unsightly addition to a home. Prior to the 1960s, buildings in the sunbelt were usually built with white roofs. But as air conditioning became widespread, the "cooler" white roof grew in disfavor. Darker roofing shingles were perceived to be more attractive, and did a better job of concealing dirt and mold. Aesthetics won out over energy conservation. In a city like Los Angeles, replacing a dark roof with a white roof can save more than $40 in air-conditioning bills for the hot summer months. Eventually, through education, the aesthetic benefits of a dark roof might be deemed less important than its energy wastefulness.

The energy consequences of bigger homes filled with more power-hungry technology is a need for more energy. Because of federal standards for appliances and heating and air conditioning equipment, the new, larger homes have only incrementally increased consumption. However, the desire for ever-bigger refrigerators and freezers, and the continued introduction of more plug-in appliances, many of which run on standby mode, promises to keep increasing the residential demand for electricity.

By the 1990s, after decades of extremely reliable service, most customers have come to expect electricity to be available when they want it and how they want it, and feel the utility has the obligation to supply the power. If the customer's preference is to keep the air conditioning on all day, it is the obligation of the utility to supply the power for this preference. Customers have become so accustomed and reliant on electricity that the 1990s consumer felt service without interruption was a right. This was far different than a few decades earlier. New York City residents tolerated the major blackout of 1965 and the inconveniences it caused, yet the minor blackout of 1999 was widely believed to be inexcusable and that Con Edison (the local utility) should compensate its customers for damages, and it did.

During prolonged heat waves which can cause blackouts and brownouts, electric utilities always request that customers limit energy consumption by raising thermostats and turning off the air conditioning when not home. It is uncertain if these requests are heeded, and if they are, it is uncertain whether conformity is out of altruism (help the utilities) or self-interest (save money).

FOOD

Just as gasoline is the energy source for the automobile engine, food is the energy source for the human engine, yet it is not common for people to think of food in this way. It is more common to look at food as a means to satisfy a hunger craving. Even among those claiming to want to lose weight, 35 percent of men and 40 percent of women are not counting calories according to the American Medical Association.

The minimum average energy requirement for a sedentary adult to survive is around 2,000 kcal a day, which rises to 4,000 or more if the person is engaged in strenuous labor much of the day. Only a very small percentage of the U.S. population is involved in strenuous labor, yet much of the population consumes over 4,000 calories each day, resulting in an America that is 50 percent overweight and 20 percent obese.

Few people do manual labor anymore. Technology has modified behavior so that most people burn 2,500 to 3,000 calories a day, not 4,000 or more calories as was common up until the 1960s. The washboard was replaced by the washing machine; the manual push mower was replaced by the power mower; the snow shovel was replaced by the snow blower; the stairs were replaced by the elevator. Technology has made it easy to be inactive, yet few individuals will blame technology for their obesity.

The tremendous growth in health and fitness clubs since the 1960s caters to those Americans who would rather burn more calories than reduce calorie intake. By working out regularly, they can overindulge. However, only a small minority of the U.S. population exercises regularly; the majority overindulges and remains overweight.

If a sedentary person consumes more than 4,000 calories a day, obesity is likely to result; yet, among this group, a failure to match food energy input with activity energy output is seldom mentioned as the reason for obesity. Because much of the population cannot control the short-term pleasure of overindulging, and despite awareness of the long-term consequences to health and appearance, some politicians have proposed that health insurance, Medicare, and Medicaid should pay for surgical procedures (stomach staple) and diet pills (Redux, Fen-Phen) to combat what they call an "overeating addiction."

MATERIALS

When given a choice among materials, determining the most energy-wise material seldom easy. Consider the energy needed to build an aluminum bicycle frame versus a steel tubular frame. The aluminum bicycle frame takes considerably more energy to build, and needs replacement more often. However, if the bicycle is meant to be a substitute for the automobile, the lighter aluminum frame material can dramatically lower the human power output needed to climb hills. The energy saved during the use of the aluminum frame will more than compensate for the greater energy needed to manufacture it.

The energy-wise choice of material for packaging—paper, plastic, tin, aluminum, or glass—can be equally tricky. Although it takes less energy to make glass and plastic bottles than aluminum cans, few buyers think of purchasing a favorite soda because it comes in glass or plastic rather than aluminum. Energy rarely enters into the buyer's decision. Price and quality concerns are foremost. Plastic wins out on price and glass on quality; rightly or wrongly, there is a perception that glass is better at not altering the taste of the product. Few consumers would be receptive to fine wines coming in plastic bottles or aluminum cans. Glass could someday compete with plastic at the lower end of the beverage market as well if the price of crude oil increased significantly. But glass must also overcome a higher freight cost (glass is much heavier than plastic).

The recycling of bottles and containers is almost universally viewed as an energy-wise and environmentally sound moral good—one of the best way to conserve energy, resources and landfill space. Usually this is true. However, few people realize that for some materials there are great energy savings, and for others very little. For instance, whereas the net energy savings to recycle aluminum cans is substantial, it can take nearly as much energy, and generate as much pollution and waste, to recycle tin cans as to produce new ones from raw materials.

A modest amount of recycling of metals occurs today. Much more can be done, and much more can be done to encourage energy-wise buying decisions as well (choosing products packaged with materials requiring less energy over those requiring more). Whether the American public is willing to invest more time and effort into recycling, and willing to alter product packaging choices solely for energy and environmental reasons, is highly questionable.

BEHAVIOR CHANGE

Energy-related behavior modification goes on continually. Advertisers market the latest household electrical technology to make life easier; tourism agencies promote exotic cruises and resorts; and governments mandate energy conservation and energy efficiency measures to lower carbon emissions and reduce energy imports. These efforts, either direct or indirect, subtle or overt, are all designed to modify behavior that affects energy consumption.

Government

Governments have taken an active role to alter behavior, to conserve energy, and to use it more efficiently. The rationale is that lower energy consumption reduces the need for additional fossil fuel power plants and the need for less crude oil imports. Since the Energy Crisis of 1973, the U.S. government's behavior modification efforts have been many and can be grouped into five categories: information campaigns, feedback, reinforcement, punishment, and reward.

Information campaigns refer to the broad range of brochures, flyers, billboards/signs, workshops, and television and radio advertisements designed to encourage energy-conserving behavior. The success of an information campaign depends on the audience paying attention and taking the message seriously; moreover, the intended audience must trust the government source, and receive confirmation from friends and associates (Stern, 1992).

A lack of trust and confirmation is one of the reasons that the energy-related informational campaigns of governments and environmental groups have faired so poorly. Despite millions being spent in the 1990s to promote conservation, energy efficiency, and renewable energy to combat global warming, the sales of energy-guzzling vehicles skyrocketed as economy car sales declined, the number of vehicles and average miles per vehicle increased, and the average home size and the number of electric appliances in each home kept rising. In a 1997 New York Times poll, when asked to rank environmental issues, only 7 percent ranked global warming first (47 percent said air and water pollution), and a CNN poll in that same year found 24 percent of Americans concerned about global warming, down from 35 percent in 1989. Since earlier informational campaigns to change behavior (for example, the supposed energy supply crisis of the 1970s was projected to only get worse in the 1980s) turned out to be erroneous, the American public viewed the government's global warming campaign much more skeptically.

Feedback modification efforts are targeted information programs that address the lack of awareness of people about the consequences, the belief being that if people are aware or educated about the negative consequences of such behavior, it is more likely that they can be convinced to engage in behavior more beneficial to the environment. For example, if the public better understood that all forms of energy consumption come with unfavorable environmental side effects, people would be more likely to conserve and use energy more efficiently. Once made aware of the deleterious environmental consequences, people would be more likely, in theory, to buy a more fuel-efficient minivan than a gas-guzzling sports utility vehicle that marketing research shows customers rarely or ever take off-road.

Reinforcement efforts include rewarding people for engaging in energy- and environmentally-beneficial behavior. High-occupancy vehicle lanes reinforce carpooling because the driver and passengers benefit with a faster trip for the ride-sharing sacrifice, and the EPA-DOE Energy Star label affixed to energy-efficient products is a sign to others that the purchaser uses energy in an environmentally friendly way. Punishments that have been tried include a fine or premium for energy use that causes pollution: the taxation of gas-guzzling automobiles. Rewards tried include tax credits for more environmentally friendly renewable energy and conservation measures, the construction of carpool park-and-ride lots, and government-mandated employer bonuses for employees who do not drive and therefore do not take advantage of subsidized parking (probably the most effective behavior modification program.

It is very difficult to determine the effectiveness of efforts to change behavior. There are those who feel a need to adopt an energy-conserving or efficient lifestyle for appearance sake, yet will assume high-energy behavior when no one is watching (Bell et al., 1990). Moreover, no universally effective method has been found for getting people to reduce energy consumption, and there is great debate as to whether it is a policy worth pursuing. First, many policy changes entail encroachments on freedoms. Since the freedom to choose is a major right that most are very reluctant to give up, passing policy that curtails freedom is controversial. Second, there is disagreement about whether human beings are rational about energy use, and actually modify behavior for any reason except self-interest (say, altruism). Third, sometimes the cost of the program exceeds the value of the energy saved, or the cost-to-benefit ratio is unfavorable. Finally, nonenergy policy has a greater impact on energy consumption than any energy policy itself. Government subsidies for home ownership, the public funding of highways, and policies encouraging suburban sprawl were far more responsible for per capita energy consumption being much greater in the United States than Japan or Europe than was any energy policy.

Corporate

From the corporate end, almost all of the behavior modification efforts directed at consumers are to get people to use more technology. It usually follows that greater technology use results in greater energy use.

To combat a corporate image of a single-mindedness toward greater consumer consumption, companies such as Dupont and 3M make great efforts at what they refer to as eco-efficiency—improving processes to reduce energy use, waste, and air pollution. The message to consumers is yes, we produce the technology you demand, but we do so in an energy-efficient way that is friendly to the environment. Dupont has been aggressively seeking to hold energy use flat, relying more on renewable sources such as wind and biomass, and is trying to reduce its 1990 levels of greenhouse gas emissions by 45 percent by 2001, and by 65 percent by 2010. The U.S. government encourages this behavior, and would like more corporations to no longer think of energy as just another cost, equal in importance with all other costs. Except for the EPA-administered punishments for pollution, most of the Federal effort is toward reinforcing and rewarding good corporate citizenship actions, not mandating them.

When questioned by electric utilities, a majority of residential customers show a willingness to consider paying a modest amount more per month for electricity powered from nonpolluting renewable energy sources, despite not knowing much about them. How many would actually choose to pay a premium for renewable energy is very uncertain. For those who are skeptical or ambivalent about the possibility of fossil fuel resources exhaustion, air pollution and global warming, the primary interest is the lowest price and best service. Early green-energy marketing efforts have shown promise in reaching those who are concerned about environmental issues. In 1999, Mountain Energy of Vermont signed up over 100,000 Pennsylvanians and Californians who will pay a 5 to 35 percent premium for electricity generation not involving nuclear power or coal. It is a surprisingly good start for Mountain Energy, who cannot actually get green power to the home, but instead must sell the concept—the green power the customer buys displaces the traditionally generated electricity in the area. Because many consumers buying the green energy are in a different region from where it is produced and therefore will not "receive" the cleaner air for which they paid a premium, it is uncertain whether green marketing programs will provide measurable environmental improvements. The result may be significant new renewable energy development, or it may just support the renewable base already in operation.

Food

Because of the huge food surplus in the United States, attributed to the high productivity of mechanized agriculture, there is probably no area of the energy consumption picture where more behavior modification takes place than food. The huge agricultural surplus keeps food products cheap, and would increase tenfold if Americans cut meat consumption in half and ate grains instead. Humans get from grain-fattened cattle only about 5 percent of the food energy they could get by eating the grain the cattle are fed.

There are thousands of special-interest groups trying to modify consumer behavior to eat more, or eat higher up the food chain. This would not be possible without a huge food surplus. It has never been easier to overeat. Even for those who lack the time or motivation to cook, the fast-food industry and microwaveable meals have made food more convenient and widely available than ever before. At the other extreme is the $33 billion a year weight loss industry promoting products to lose the weight gained "eating down" the food surplus. In the middle is the U.S. Department of Agriculture (USDA) with an inherent conflict of interest: One arm of the organization promotes the consumption of food while another arm publishes the highly political and ubiquitous food pyramid of good eating.

Since Americans enjoy the cheap food supply made possible from a huge agricultural surplus, and there seems to be no desire to reject technology and go back to a reliance on manual labor, the food surplus problem of an overweight and obese America is likely to remain for years to come.

OUTLOOK

Easy access to inexpensive energy has come to be viewed as a basic right. The American public goes about its daily life largely optimistic, feeling that any fossil-fuel shortage will be alleviated by new breakthroughs in developing supplemental sources, and that new end-use technology will be developed that can be powered by these new energy sources. Energy conservation and energy efficiency are lifestyle options. However, if the day ever comes when energy conservation or an accelerated adoption of energy-efficient products will need to be mandated, the American public would be more likely to choose the energy efficiency route because it does not necessarily entail sacrifice.

John Zumerchik

See also: Air Travel; Bicycling; Capital Investment Decisions; Communications and Energy; Economically Efficient Energy Choices; Economic Growth and Energy Consumption; Freight Movement; Green Energy; Government Agencies; Industry and Business, Productivity and Energy Efficiency in; Materials; Propulsion; Traffic Flow Management.

BIBLIOGRAPHY

Bell, P. A.; Baum, A.; Fisher, J. D.; and Greene, T. E. (1990). Environmental Psychology,3rd ed. Fort Worth, TX: Holt, Rinehart and Winston Inc.

DeSimone, L. D., and Popoff, F. (1997). Eco-Efficiency: The Business Link to Sustainable Development. Cambridge, MA: MIT Press.

Energy Information Administration. (1997). Household Vehicles Energy Consumption, 1994. Washington, DC: U.S. Department of Energy.

Engel, J. F.; Blackwell, R. D.; and Miniard, P. W. (1998). Consumer Behavior,8th ed. Hinsdale, IL: Dryden Press.

Farhar, B. C. (1994). "Trends: Public Opinion about Energy." Public Opinion Quarterly 58(4):603-632. Farhar, B. C., and Houston, A. (1996, October). "Willingness to Pay for Electricity from Renewable Energy." National Renewable Energy Laboratory, NREL/TP-461-20813.

Gardner, G. T., and Stern, P. C. (1996). Environmental Problems and Human Behavior. Englewood Cliffs, NJ: Allyn & Bacon.

Kempton, W. (1995). Environmental Values in American Culture. Cambridge, MA: MIT Press.

Kempton, W., and Neiman, M., eds. (1987). Energy Efficiency: Perspectives on Individual Behavior. Washington, DC: American Council for an Energy Efficient Economy.

Nye, D. E. (1998). Consuming Power: A Social History of American Energies. Cambridge, MA: MIT Press.

Smil, V. (1999). Energies: An Illustrated Guide to the Biosphere and Civilization. Cambridge, MA: MIT Press.

Socolow, R. H. (1978). "The Twin Rivers Program on Energy Conservation in Housing: Highlights and Conclusions." In Saving Energy in the Home. Cambridge, MA: Ballinger Publishing Company.

Stern, P. C. (1992). "What Psychology Knows About Energy Conservation." American Psychologist 47:1224-1232.

U.S. Census Bureau. (1992). Census data, 1980 and 1990, Journey-to-Work and Migration Statistics Branch, Population Division, Washington, DC.

Veitch, R.; Arkkelin, D.; and Arkkelin, R. (1998). Environmental Psychology: An Interdisciplinary Perspective. Englewood Cliffs, NJ: Prentice-Hall.

41. Behavior

See also 28. ATTITUDES ; 279. MOODS ; 334. PSYCHOLOGY .

aberrance, aberrancy

the condition or state of being deviant or aberrant.

abnormalism

1. having a tendency towards, or being in a state of abnormality.

2. something that is abnormal.

abnormalist

a person who is characterized as being in some way abnormal.

adventurism

impulsive, rash, or irresponsible actions or attitudes, especially in the sphere of public life. —adventurist, n . —adventuristic, adj.

alarmism

the attitudes and behavior of one who exaggerates dangers or always expects disaster. —alarmist , n.

alogy

Obsolete, illogicality, unreasonableness. —alogic, alogical, adj.

amazonism

the taking on of masculine habits and occupations by women.

Arcadianism

the dress and conduct suitable to a pastoral existence, usually with reference to the idealized description of pastoral life in literature. —Arcadian, n., adj.

arrivism

1. the state of having recently achieved wealth or position, especially by unscrupulous or unethical means.

2. behavior typical of arrivism. —arriviste, n., adj.

asceticism

a severe self-deprivation for ethical, religious, or intellectual ends. —ascetic, n., adj.

atrabilarian

1. a sad and gloomy individual.

2. an irritable and bad-tempered person. —atrabilious, adj.

attitudinarianism

the practice of striking poses, either to mask or to express personal feelings. —attitudinarian, n.

attorneyism

the characteristics attributed to attorneys; slyness; unscrupulousness.

automatism

an automatic or involuntary action. —automatist, n.

autophoby

Rare. an abnormal fear of being egotistical, of referring to oneself.

babuism, babooism

Derogatory. the practices of Hindus who had only a slight English education. From bābū, a Hindi title equivalent to Sir or Mr.

Barnumism

showmanship or any activity taking advantage of people’s credulity or desire for sensational entertainment, as practiced by P.T. Barnum (1810-91).

bashawism

the characteristics of a bashaw, especially tyranny and imperiousness.

beatnikism

attitudes or behavior typical of a beatnik or one who has rejected conventions of society.

bestiality

a debased brutality, the opposite of humane activity: “I have lost the immortal part of myself, and what remains is bestial.” (Othello). See also 364. SEX .

bizarrerie

strangeness or grotesqueness, especially strange or unconventional behavior.

blackguardism

behavior typical of a blackguard, characterized by use of obscene language and by roguish actions. —blackguardery, n. —blackguardly, adj.

bohemianism

the practice of individualistic, unconventional, and relaxed conduct, of ten in an artistic context, expressing disregard for or opposition to ordinary conventions. —bohemian, n., adj.

boobyism

conduct characteristic of a stupid person or clown. —boobyish, adj.

braggartism

a braggart’s usual activity; bragging. —braggartist, braggart, n.

brutalitarianism

the practice of advocating or engaging in brutality. —brutalitarian, adj.

brutism

the set of attributes that characterize a brute. —brutish, adj.

bullyism

the actions of a bully.

careerism

the characteristics associated with one who advances his career even at the expense of his pride and dignity. —careerist, n.

ceremonialism

an addiction to ceremonies or ritualism, especially in social and other nonreligious contexts. —ceremonialist, n.

characterology

the study of character, especially its development and its variations. —characterologist, n. —characterologic, characterological, adj.

charlatanism

the quality of having characteristics of a fraud. —charlatanic, adj.

consuetude

a habit or custom; usual behavior.

coxcombry

foolish conceit or vanity; behavior typical of a coxcomb.

daredevilism

reckless or foolhardy behavior. Also called daredeviltry . —daredevil, n.

debacchation

Obsolete, raving or maniacal behavior, as that of a bacchanal.

decorum

proper behavior; action that is seemly and in good taste. —decorous, adj.

die-hardism

the attitudes or behavior of one who stubbornly holds on to something, as an outdated view, untenable position, etc. —die-hard, n., adj.

dilettantism

an admiration of or interest in the arts, often used pejoratively to designate a shallow, undisciplined, or frivolous attraction. —dilettante, n., adj. —dilettantish, adj.

donkeyism

1. an action characterized as being donkeylike; foolishness.

2. the characteristic of being like a donkey. —donkeyish, adj.

do-nothingism

idleness or indolence as a habit or regular practice.

dowdyism

the habit of being shabbily dressed. —dowdyish, adj.

dramaticism

the habit of performing actions in a histrionic manner.

ergoism

a pedantic adherence to logically constructed rules.

erraticism

an action or behavior that deviates from the norm; unpredictability in behavior.

exhibitionism

1. a deliberately conspicuous or exaggerated mode of behavior, intended to gain attention.

2. the abnormal practice of indecent exposure. —exhibitionist, n. —exhibitionistic, adj.

faineance, faineancy

laziness; the state of being idle. —faineant, adj.

fairyism

the quality of being a fairy or having fairylike characteristics.

fanfaronade

swaggering boastfulness; vainglorious speech or behavior. —fanfaron, n.

faustianism

spiritual or intellectual dissatisfaction combined with a desire for power or material advantage. After Johann Faust (c.1480-c.1538), German scholar portrayed by Marlowe and Goethe. —faustian, adj.

fiendism

Rare. evil attitudes and actions.

flunkyism, flunkeyism

1. the quality or state of being a servant or toady.

2. behavior typical of flunkyism. —flunky, flunkey, n.

formularism

the condition of adhering solely to set formulas. —formularistic, adj.

fossilism

behavior typical of an earlier time; old-fashioned or stuffy attitudes; fogyism.

fraternalism

the condition of having brotherly qualities. —fraternalist, n. —fraternalistic, adj.

functionarism

the administrative duties of officials. —functionary, n., adj.

gangsterism

the habit of using organized violence to achieve one’s ends. —gangster, n.

gasconism

boastful or bragging behavior. Also gasconadc .

gelastic

1. inclined to laughter.

2. laugh-provoking in conduct or speech.

gnathonism

the extremely obsequious behavior of a sycophant. —gnathonic, adj.

gourmandism, gormandism

1. a strong penchant for good food; gourmetism; epicurism.

2. gluttony. —gourmand, gormand, n., adj.

grandeeism

attitudes and actions modeled on the grandees, Iberian nobles of the highest rank.

gypsyism, gipsyism

the activities and style of living attributed to gypsies. —gypsy, gipsy, n. —gypsyish, gipsyish, adj.

harlequinade

a performance involving Harlequin or other characters of the Commedia dell’Arte; hence, buffoonery or clownish behavior. Also harlequinery.

hermitism

the practice of retiring from society and living in solitude, based upon a variety of motives, including religious. Also called hermitry, hermitship. —hermitic, hermitical, adj.

histriconism

histrionicism.

histrionicism

a tendency to theatrical or exaggerated action. Also histriconism. —histrionics, n. —histrionic, adj.

hoboism

the state of being a hobo or vagrant.

holidayism

a dedication to taking holidays.

hooliganism

lawless behavior or conduct typical of a hooligan.

horsyism, horseyism

looking or acting in some way like a horse. —horsy, horsey, adj. —horsily, adv.

Hottentotism

any behavior attributed to the Hottentots, in particular, a kind of stammering or stuttering.

hoydenism

ill-bred, boisterous, or tomboyish behavior in a woman. —hoyden, n. , —hoydenish, adj.

humbuggery

1. pretentious behavior or attitudes.

2. imposing or deceptive behavior. —humbug, humbugger, n.

humoralism, humouralism

an obsolete physiological explanation of health, disease, and behavior, asserting that the relative proportions of four elemental bodily fluids or humors (blood-sanguinity, phlegm-sluggishness, black bile-melancholy, and yellow bile-choler) determined a person’s physical and mental constitution. —humoral, humoural, adj.

hyphenism

division of patriotic loyalties, ascribed by some to foreign-born citizens in the United States.

idiocrasy

an idiosyncrasy or personal mannerism or peculiarity.

idiosyncrasy

a mannerism, action, or form of behavior peculiar to one person or group. —idiosyncratic, idiosyncratical, adj.

impudicity

lack of shame or modesty.

indecorum

1. indecorous, improper, or unseemly behavior.

2. an indecorous thing or action.

Indianism

the customs or traditions of Indians, especially American Indians. —Indianist, n.

insurrectionism

the quality of revolting against established authority. —insurrectionist, n., adj. —insurrectionary, adj.

irascibility

a tendency to irritability and sudden fits of anger. Also called irascibleness . —irascible, adj.

Johnsonianism

the quality of having traits or characteristics like those of Samuel Johnson. —Johnsonian, n., adj.

juvenilism, juvenility

Often pejorative. a mode of action or thought characterized by apparent youthfulness. —juvenile, n., adj.

landlordism

the actions and characteristics of a landlord. —landlordly, adj.

larkinism

frolicsomeness.

larrikinism

the state of being noisy, rowdy, or disorderly. —larrikin, adj., n.

libertinism

a tendency to unrestrained, often licentious or dissolute conduct. Also libertinage . —libertine, n., adj.

lionism

the pursuit or adulation of celebrities. —lionize, v.

litigiousness

1. an inclination to dispute or disagree with others, esp. through civil suits.

2. argumentativeness. —litigious, adj.

Londonism

the customs and characteristics of London and of those who reside there. —Londonish, adj.

macaronism, maccaronism

a tendency to foppishness. —macaroni, maccaroni, n.

maenadism

behavior characteristic of a maenad or bacchante; raging or wild behavior in a woman. —maenadic, adj.

maidism

1. the state or quality of being a maid, a young or unmarried woman.

2 . behavior or attitude typical of maidism.

mannerism

a style of action, bearing, thought, or speech peculiar to an individual or a special group. See also 23. ART . —mannerist , n. —manneristic, adj.

martinetism

an emphasis on scrupulous attention to the details of methods and procedures in all areas of life. —martinet, n. —martinetish, adj.

maudlinism

Rare.

1. a tendency in temperament to be mawkishly sentimental and tearfully emotional.

2. a degree of drunkenness characterized by mawkish emotionalism. —maudlin, adj.

melodramatics

behavior typical of that portrayed in a melodrama, i.e., characterized by extremes of emotion.

mercuriality

1. the state or quality of having a lively, fickle, volatile, or erratic attitude or charaeter.

2 . an instance of such behavior. —mercurial, adj.

milksopism

1. the state or quality of being a weak and ineffectual person.

2 . behavior or attitudes typical of a such a person.

mimicism

an intense (and sometimes injurious) tendency to mimicry.

mountebankism

boastful and pretentious behavior; quackery or any actions typical of a mountebank. Also mountebankery .

muckerism

behavior characteristic of a boorish person.

mutualism

the principle or practice of mutual dependence as the condition of individual and social welfare. —mutualist, n.

namby-pambyism

weak or insipid behavior or attitude. —namby-pamby, n., adj.

Negroism

a quality or trait distinctive of Negroes.

ninnyism

conduct characteristic of a ninny, or silly fool. —ninnyish, adj.

nomadism

a rootless, nondomestic, and roving lifestyle. —nomadic, adj.

nudism

the practice of going nude. —nudist, n., adj.

Occidentalism

the characteristics and customs of people situated in western regions, especially the Western Hemisphere, as western European countries and the United States. —Occidentalist, n.

ogreism

the condition of resembling an ogre in actions and characteristics. —ogreish, adj.

opportunism

the conscious policy and practice of taking selfish advantage of circumstances, with little regard for principles. —opportunist, n. —opportunistic, adj.

Orientalism

the habits, qualities, and customs of Oriental peoples. —Orientalist, Orientality, n.

parrotism

mindless imitation. Also called parrotry .

particularism

the adherence to an exclusive subject, interest, or topic. —particularist, n. —particularistic, adj.

parvenuism

1. behavior or attitudes typical of one who has recently acquired wealth or social position.

2 . the state or quality of being a parvenu or upstart. —parvenu, n., adj.

patricianism

1 . the state of being a member of one of the original citizen families of ancient Rome.

2 . the state of being noble or high born. —patriciate, n.

plebeianism

the quality of having common manners, character, or style. —plebeian, n., adj.

pococurantism

a tendency to conduct expressing indifference, nonchalance, or lack of concern. —pococurante, pococurantist, n. —pococurante, adj.

poltroonism

the characteristics associated with being a coward or wretch. Also called poltroonery . —poltroonish, adj.

polypragmatism

a penchant for meddlesomeness and officiousness. Also polypragmacy, polypragmaty . —polypragmatist, n. —polypragmatic, adj.

pornerast

one whose conduct is unchaste, licentious, or lewd.

praxeology, praxiology

the study of human behavior and conduct. —praxeological, adj.

preciosity

excessive fastidiousness or over-refinement in language or behavior.

precipitancy

hasty or rash action, behavior, etc.; undue or ill-considered haste. —precipitant, adj.

priggism

the strict adherence to correctness of behavior. —prigger, n. —priggish, adj.

profligacy

1 . dissolute or immoral behavior.

2. reckless and extravagant spending or behavior. —profligate , adj.

protagonism

the actions and qualities of a protagonist. —protagonist , n.

protervity

a tendency to peevish, petulant, or insolent conduct.

psychagogics, psychagogy

a method of affecting behavior by assisting in the choice of desirable life goals. —psychagogue , n.

puppyism

affected or impertinent behavior; conceit.

quixotism

a tendency to absurdly chivalric, visionary, or romantically impractical conduct. —quixotic, quixotical, adj.

rabulism

Rare. a tendency to railing and quibbling. —rabulistic, rabulous, adj.

reactionism

the condition of being reactionary or resistant to change. —reactionist , n., adj.

reporterism

the characteristics of a reporter.

reunionism

the qualities of a reunion or social gathering. —reunionist , n.

revolutionism

the state of being revolutionary. —revolutionary, revolutionist, n. —revolutional, revolutionary, adj.

routinism

the excessive adherence to a routine. —routinist , n.

rowdyism

noisy, quarrelsome, or disorderly conduct or behavior. —rowdy , n., adj.

ruffianism

behavior typical or characteristic of a brutal and violent person. —ruffian , n.

Satanism

diabolical behavior. —Satanist , n.

savagism

the condition of having uncivilized or primitive qualities. —savagedom , n.

schoolboyism

the practices characteristic of a schoolboy. —schoolboyish , adj.

scoundrelism

the characteristics and behavior of a scoundrel. —scoundrelly , adj.

seclusionist

a person who seeks solitude or removes himself from the society of others; a recluse.

sensorialism

the quality of having sensation. —sensorial . adj.

seraphism

Archaic. an ecstatic devotion, especially religious.

sermonist

1 . a person who delivers sermons.

2 . a person who adopts a preaching attitude.

Shandyism

a tendency to whimsical conduct in accord with absurd theories from past ages. [Allusion to the actions of Walter, father of the hero in Sterne’s Tristram Shandy. ]

spasmodism

a tendency to conduct marked by outbursts of strong emotion. —spasmodist , n. —spasmodic, spasmodical, adj.

Sundayism

activity characteristic of the observance of Sunday as a holy day.

supermanism

the condition of having qualities or traits like those of a superman. —supermanly , adj.

sybaritism

a love of luxury. [Allusion to Sybaris, a Greek colony in Italy not-ed for its luxury.] —sybarite, n. —sybaritic , adj.

sycophantism

the practice of self-serving or servile flattery. Also called sycophancy . —sycophant , n. —sycophantic , adj.

sympathism

the condition of having coinciding emotions in two or more people.

tantalism

Obsolete. a form of teasing or harassment in which a hope of some good or benefit is instilled in the victim, only to be repeatedly dashed and the reward shown to be unattainable.

tartufflsm

hypocrisy. [Allusion to Molière’s hypocritical hero, Tartuffe.] Also called tartuffery.

theatricalism

a tendency to actions marked by exaggerations in speech or behavior. Also called theatricism.

tidyism

the habit of extreme neatness.

Timonism

a personal despair leading to misanthropy. [Allusion to Shake-speare’s Timon of Athens. ]

toadyism

a fawning flattery, obsequiousness, or sycophancy. —toady , n. —toadyish , adj,

tokenism

formal or superficial compliance with a law, requirement, convention, etc.

tomboyism

the conduct characteristic of a tomboy, a boyish girl. —tomboyish , adj.

Turcism, Turkism

Obsolete, the attitudes and actions of the Turks.

ultracrepidarianism

the habit of giving opinions and advice on matters outside of one’s knowledge or competence. —ultracrepidarian , n., adj.

vagabondism

1 . the tendency to wander from place to place without a settled home; nomadism.

2 . the life of a tramp; vagrancy. Also called vagabondage. —vagabond , n., adj.

vandalism

the malicious destruction or defamation of public or private property. —vandal, vandalization, n. —vandalish , adj.

vanguardism

the actions or thoughts of members of a vanguard, those at the forefront of a movement, fad, etc. —vanguardist , n.

Victorianism

the affection for or emulation of Victorian tastes or thoughts.

Vikingism

the actions characteristic of a Viking, i.e., savagery, rapaciousness, etc.

voyeurism

the compulsion to seek sexual gratification by secretively looking at sexual objects or acts; the actions of a Peeping Tom. —voyeur , n. —voyeuristic , adj.

vulpinism

Rare. the state or quality of being foxlike, especially crafty or cunning. —vulpine , adj.

vulturism

behavior or character typical of a vulture, especially in the figurative sense of being rapacious. —vulturous , adj.

werewolfism

the quality of having the traits of a werewolf.

Yahooism

a penchant for rowdyism. [Allusion to Swift’s characters in Gulliver’s Travels. ]

yokelism

1 . the state or quality of being a yokel or country bumpkin.

2 . behavior, language, etc, typical of a yokel.

zanyism

the style of a zany or buffoon.

zealotism, zealotry

a tendency to undue or excessive zeal; fanaticism.

zelotypia

Obsolete.

1. abnormal zeal.

2 . morbid jealousy. —zelotypic , adj.

Behavior

Insect behavior can be understood as the result of the complex integrated actions of insects in response to changes to their external (e.g., light, temperature, humidity, other insects) and internal (e.g., the level of a particular hormone) environments. In broad terms, insects exhibit two basic kinds of behavior: innate and learned. Innate behavior, commonly referred to as instinct, is based on inherited properties of the nervous system, whereas learned behavior is acquired through interaction with the environment involving adaptive changes due to experience. Whether a particular behavior pattern is inherited or learned is not always easy to determine, because some inherited behaviors may be modified by experience.

Innate behavior is responsible for simple reflexes, such as extending the proboscis to feed or turning over when falling on the back; for orientation mechanisms, such as leaving an unsuitable environment (for example, water bugs flying away from a drying pond); and for appetitive behavior, such as going toward a potential prey (e.g., female mosquitoes approaching a source of carbon dioxide to get a blood meal). Learned behavior involves the acquisition and storage (memory) of environmental information and the effects that this stored information has on the behavior of the insect. An example of learned behavior is the building of cognitive maps in several wasps, bees, and ants, which use landmarks to establish specific foraging routes or to locate their nests.

Sexual behavior

Insects show diverse and remarkable modes of reproduction. Parthenogenesis, the development from an unfertilized egg, is common among many species of aphids and orthopteroid insects, such as walking sticks. In these species, the males are unknown or rare, and females maintain the population by cloning themselves. Some moths and one beetle practice gynogenesis, in which females and males copulate but the sperm is used only to activate the development of the eggs, not to fertilize them. However, most insects reproduce sexually, males producing sperm that unite with eggs developed within females. There are some unusual types of sexual reproduction found in insects. A few scale insects (coccids) are hermaphrodites, producing both sperm and eggs and fertilizing themselves. All female ants, wasps, and bees display sexual parthenogenesis, in which unfertilized gametes generate only males with half the normal number of chromosomes. Numerous insects alternate between sexual and asexual reproduction at different stages of their life cycle.

Sexual behavior involves the location of a potential mate, usually followed by courtship, mating, and oviposition (egg laying). Males exhibit a drive to secure mates, which leads to competition for access to females. They typically are more colorful than females and can have showy structures to attract the females' attention, for example, large horns on the head of the atlas beetle, Chalcosoma caucasus; elongated mandibles in the Chilean stag beetle, Chaisognathus granti; and a pair of capitate setae on the head of the Mediterranean fruit fly, Ceratitis capitata. Females generally have duller colors and are larger in size. This phenomenon is called sexual dimorphism. An extreme case of sexual dimorphism is found in scale insects—females lack wings and are sessile (remain immobile and attached to the substrate), with reduced legs, whereas males look like normal winged insects. Females can choose among many potential partners, and their preferences are expected to raise their genetic success and, in turn, exert pressure on males favoring traits desirable by females. This is known as sexual selection.

Insect mating systems can be classified into three basic types: polygyny, polyandry, and monogamy. Polygyny results when some males copulate with more than one female in a breeding season, polyandry is when one female mates with more than one male, and monogamy refers to the male and female's having a single partner per breeding season. The most common form of mating in insects (and in other animals too) is polygyny. This is probably due to the vast supply of sperm the male possesses for fertilizing females, whereas each female has a relatively small number of eggs. Females mate simply to acquire enough gametes to fertilize their eggs, and one mating is usually sufficient.

Location of a potential mate

Insects use various communication strategies to locate mates, including mechanical, visual, and chemical tactics. Several families of insects use acoustic signals to locate mates. Calling sounds can be generated simply by the wings as an indirect result of flight, as in mature mosquito females and other flies, or by rubbing together parts of the body—a process called stridulation. Grasshoppers, crickets, cicadas, some bark

beetles, and water boatmen stridulate to call for mates. In Magicicada, the males sing in chorus, and this aggregation song is responsible for assembling both females and males. Grasshoppers rub the hind legs against a ridge in the forewing, causing the wing to vibrate. In cicadas, males have an area of thin cuticle in the abdomen, called a tymbal, underlined by several air sacs that amplify the click produced when a muscle pulls the tymbal in; the calls consist of a rapid succession of clicks. Some beetles produce mechanical signals by banging the head or abdomen against the ground to attract females, and water striders and some water beetles generate waves in the water to communicate with their potential mates.

Visual signals can be passive, as when a variety of colors are transmitted in a single distinctive message using body surfaces as signal generators, or active, as when body parts are moved in a variety of positions, thus creating a rapid sequence of signals. With the exception of bioluminescence in fireflies (beetles belonging to the families Lampyridae, Phengodidae, and Elateridae), visual signals are restricted to diurnal use. In the case of several swarming insects, such as various flies, mayflies, and caddisflies, individual males in a swarm attract females' attention by fluttering up several meters and then dropping down, reflecting the light with their wings. Firefly males usually fly around the habitat emitting flashing lights that vary from species to species with respect to the color, rate, length, and intensity of flash pulse. Females, perched on plants or rocks, return the message. In some species, females glow continuously or respond only to continuously glowing males, whereas in others only the male produces the light signals.

Olfactory signals to locate mates are widespread among insects; several moths, some flies, bumblebees, harvester ants, boll weevils, scorpion flies, and some bark beetles, among others, use them. Males, females, or both produce attractant molecules, called sex pheromones, from specialized glands. Pheromones are released into the air and dispersed by the wind, or, as in some types of territorial species, they can be used to scent mark a plant in the territory. Antenna receptors are able to detect just a few molecules of the pheromone in the air, allowing an insect to follow the trail leading to the opposite sex even when the insect is located at considerable distance from the source.

Some plants mimic the shape and color of certain insects to attract them to their flowers and to use them as pollinators. A well-known example is that of bees and certain orchids that resemble bee females and even produce bee pheromones. Pheromones also are produced synthetically and used as lures to trap or control the reproduction of some pest insects, such as fruit flies (Bactrocera dorsalis and Ceratitis capitata), yellow jackets (Vespula species), and gypsy moths (Lymantria dispar).

Mating

Many of the cues that act in mate location serve as releasers of mating or courtship behavior as well, leading eventually to copulation. In all insects, fertilization of eggs takes place inside the female reproductive ducts. In primitive insects, such as springtails, there is no mating; the male deposits sperm in packets called spermatophores and scatters them on the ground. Competition among males takes the form of males eating the spermatophores of other males. The female must locate the spermatophore to fertilize her eggs. In silverfishes, the male guides the female to his spermatophore by building a net of silken threads converging on it.

During courtship, escape and attack responses are momentarily inhibited. Insects display an amazing variety of mating patterns. Some are simple and consist in the coming together and copulation of the male and female; others involve elaborate courtship patterns. For example, in some Panorpa scorpion flies, a male offers a nuptial gift in the form of prey food to a female and copulates with her while she eats.

In most dragonflies and damselflies, females and males mate several times. A male can contribute to a substantial percentage of the progeny if he is the first one to grab and inseminate the female. In some species a female does not mate more than once in a particular oviposition episode, so that the male that is able to grasp her and mate with her before she oviposits is the most likely to fertilize the eggs that are laid. In numerous dragonfly and damselfly species, males are territorial, guarding a suitable oviposition site from other males. It has been found that in some species the male penis is used not only for insemination but also to remove sperm deposited by previous males from the female sperm storage organ, ensuring the fertilization of the eggs with his own sperm. This is known as sperm precedence or sperm competition. There are several mechanisms that help prevent the female from copulating with other males. For example, dung flies, dragonflies, and damselflies guard or protect the female after copulation, love bugs copulate for a prolonged period of time, male honeybees detach the genitalia and leave it inserted in the female genital opening after mating, and vinegar flies of the genus Drosophila transfer a chemical substance that makes the female unreceptive to other mates.

Egg laying

Insects are unique in the possession of an ovipositor, a specialized organ on the female abdominal tip used to lay her eggs, which usually consists of three pairs of plates. This device allows the female to deposit eggs in safer places, in crevices or inside plant tissues or other substrates. Ovipositors

Some insects simply drop their eggs at the oviposition site, as is the case with some dragonflies, which can be seen touching the water surface with the tip of the abdomen at the ponds where they breed. Others paste them to a certain substrate. In certain mayflies, the gravid female drops into the water, where her abdomen breaks, setting her eggs free. Other aquatic insects, such as aquatic beetles and damselflies, insert their eggs into the mud or place them in the leaves or stems of plants growing on the margins of ponds or streams; still others, like some mosquitoes, make egg rafts.

Parental care

Once the eggs have been laid, most parent insects simply leave. Among cockroaches and praying mantids, the female secretes a cover around the eggs that provides protection against predators and dehydration; some cockroach females carry this egg case until the larvae emerge. Female mealybugs, scale insects, and some beetles protect their eggs by shielding them with their bodies, other beetles may carry them beneath their bodies, and some carabid beetles construct depressions in the soil for the eggs and clean them regularly until they hatch, to prevent fungi from growing on them. In the case of the chrysomelid beetle, Acromis sparsa, the female stays with her offspring until they reach adulthood; the larvae remain aggregated, feeding on the same leaf, so that the mother can shield them with her body in case of danger. Earwig females oviposit in burrows in the ground and guard the eggs until they hatch.

Insect males are mainly polygynous, and for this reason it is not advantageous for them to invest effort in parental care. There are some exceptions. The male of the scarab beetle, Lethrus apterus, helps the female construct a burrow and gather leaves to provision the brood cells. In the carrion beetle Necrophorus the male assists the female in regurgitating liquefied carrion to feed their offspring, which reside in a nest of carrion. Males of certain bark beetle and sphecid wasp species stay close to the nests of their mates and repel parasites and rival females that try to enter the burrows. The best-known examples of paternal care in insects are found among the water bugs of the family Belostomatidae. In the genera Abedus and Belostoma the female lays her eggs on the back of the male after mating. The male takes exclusive care of the progeny; he ventilates the eggs, prevents fungus from growing on them, and assists in the emergence of the larvae. In Lethocerus, another genus of the same family, the female lays eggs on a stick or plant stem at the level of the water surface, and the male is stationed close by, to guard them against predators.

A digger wasp female builds one or several burrows in the ground and provides the eggs with a certain type of prey, usually spiders or other insects; she then inserts an egg into each prey item and closes the burrow. The prey is alive but paralyzed with a substance injected together with the egg. When the wasp maggot emerges, it eats the prey from the inside out. In some species, the female keeps bringing prey to the larva until it pupates.

Feeding behavior

Some insects are surrounded by their food from the time of hatching, as a result of the oviposition habits of the parent. In the case of many insects that feed on plants, the mother places the eggs on the host plants or, in scavenger or parasitic insects, on suitable detritus or hosts. Among social insects, the larvae are incapable of searching for their own food, and the workers are in charge of feeding them. Most insects, however, must search for their food.

Insects feed on an almost endless variety of food and in many different ways. About half of insects are herbivores, feeding on plants. The most common plant hosts are flowering plants, but some insects feed on ferns, fungi, and algae too. Certain insects are polyphagous and show no preference for any particular host plant. An example is the desert locust, Schistocerca gregaria, which, when migrating, feeds on all the plants it finds along its way. Other insects are oligophagous, specializing in certain groups of plants, for example, Pieris butterflies, which feed on Cruciferae and other plants with mustard oils. Still others are monophagous, feeding on a single plant species, for example, the weevil Scyphophorus yuccae, which feeds only on Yucca.

Variation also exists as to the part of the plant that is consumed. Soil mealy bugs, wireworms, cicada larvae, and white grubs, among others, specialize on roots; bark beetles, carpenter ants, and termites on woody parts; psyllids, aphids, leafhoppers, leaf-mining larvae of moths, flies, beetles, and sawflies on leaves; and bees, wasps, beetles, butterflies, and moths on nectar and pollen of flowers. Some herbivorous insects inject a chemical into the plant that induces it to grow abnormally and form a gall. The feeding of the insect usually stimulates the formation of a gall, though in some cases it is initiated by oviposition. A plant gall may have (e.g., galls of psyllids, aphids, and scales) or lack (e.g., galls of moths, beetles, flies, wasps) an opening to the outside.

A few insects are specialized in the production of "fungus gardens." This peculiar habit is found in some ants, termites, and ambrosia beetles. These fungus-growing insects nest in the ground, where they excavate a complex system of galleries and chambers. They cut up leaves and take them to special chambers in the nest, where they are chewed up and seeded with a fungus, which they tend and eat.

An insect can be attracted to the food source from a distance by visual or olfactory clues, but the final selection occurs when the insect is in direct contact with the host. Physical characteristics of the plant, olfaction, and contact chemoreception play a part in this process. For example, in a leafhopper the first attraction to a plant is through color; thus, they land on host and non-host plants of similar color. The leafhopper finally determines the identity of the host plant by touching the surface with its proboscis or by inserting the proboscis into the plant for a short distance. Chemical substances characteristic of the plant then are detected, and the leafhopper stops feeding activities if the plant is not an appropriate host and keeps feeding if it is one.

Carnivorous insects feed on other animals, which are mainly other insects. There are two general sorts of carnivores: predators and parasites. Predator insects are active and seek their prey, usually consisting of one or more smaller insects per meal, whereas parasites live in or on the body of their hosts during at least part of their life cycle, take successive meals from the much larger host, and typically do not kill the host or do so only gradually.

Damselflies and dragonflies, both during larval and adult life; tiger, ground, and ladybird beetles; lacewings and some true bugs; robber flies and larvae of syrphid flies are examples of predators. Most predators actively forage for their prey, but some are ambush hunters. Antlion larvae, for example, dig a pit with sloping sides in the sand and bury themselves

at the bottom with only the head exposed. When an ant or other small insect walks on the margin of the pit, the antlion provokes a landslide, throwing sand with its head, which causes the insect to roll down to its open mandibles. Larvae of tiger beetles live in a vertical burrow in the ground; when an insect comes within range, the larva extrudes about half of the body and grabs the prey with its long, sickle-shaped mandibles. Larvae of caddis flies weave a net of silken threads with which they capture small organisms in the water. Praying mantids and water bugs sit and wait for their prey to come their way; when the prey is close enough, it is taken and held by the fast extension of the raptorial forelegs. In a similar way, some dragonfly larvae wait motionless and strike at passing prey, extending the labial mask with incredible speed and accuracy.

Most hunters have large eyes, since only visual stimuli are fast enough to allow them a rapid reaction to a moving prey. After the capture, recognition is mainly tactile. In predaceous forms with subterranean habits and poorly developed eyes, the localization of prey is largely olfactory. Once they capture a prey, many predators restrain the prey's movements

by mechanical strength and tear it to pieces with the mandibles. Predators with sucking mouthparts, such as true bugs, robber flies, and some lacewing and beetle larvae, inject salivary secretions that paralyze and kill the prey and then suck the liquefied organs, discarding the empty cuticular shell.

There are parasitic insects on vertebrates and on other insects and arthropods. Some are ectoparasites, living on the outside of their hosts, and others are endoparasites, living inside the host's body. Some parasites feed on only one host species and others on a group of related host species; still others have a wide range of hosts. Lice are an example of ectoparasites of vertebrates; both larva and adult are completely dependent on the host, on whom they spend their entire life cycle. Fleas, which also are ectoparasites on vertebrates, are less dependent on the host; they frequently change hosts and spend some time away from the host as adults. The larval stage is not spent on the host's body. Mosquitoes and some other blood-sucking insects, such as "no-seeums," bed bugs, and assassin bugs, feed from the host only for brief periods; often it is only the females, which require a blood meal to produce eggs.

Ectoparasites of other insects, such as certain "no-seeums," suck blood from the wing veins of lacewings and dragonflies. In many insects the first larval stage is active, whereas the older larvae are parasitic or fixed predators of a specific host. For example, larvae of meloid beetles, called "triangulins," wait in flowers that the parent bee may visit. The active triangulins climb onto the bee, attaching themselves to the bee's hairs with their claws, and are carried in this way to the bee's nest, where they become internal parasites of the bee's eggs or larvae.

Several larvae of flies are endoparasites of vertebrates, invading open sores, alimentary ducts, and nasal cavities; this phenomenon is called myasis. Gasterophilus bot flies lay their eggs on the fur coats of horses. When the horse licks its hair, the larvae hatch and affix themselves to the horse's tongue. They then pass into the digestive canal and attach themselves to the stomach or intestinal wall, causing ulcers. The fly Oestrus ovis places its larvae on the nostrils of sheep, where they crawl and enter the frontal sinus, causing vertigo. Cordylobia anthropophaga maggots produce ulcerated ridges in the skin of humans, dogs, and mice.

Most endoparasitic insects of other insects differ from endoparasites of vertebrates in that they reach a size equal to that of the host and eventually kill it: they are called parasitoids. Most parasitoids live and feed as larvae inside the host and become free-living adults after killing the host. Tachinid and sarcophagid fly larvae attack grasshoppers, caterpillars, true bugs, and wasp larvae, but most parasitoids are found among the ichneumonoid, chalcidoid, and proctrotrupoid wasps. Some parasitoids are very specific to their hosts— restricted to a single or a few species of insects. Parasitoids often regulate numbers of pest insects and are therefore important components of biological control programs.

Some insects are detritivores, feeding on decaying materials, such as carrion, leaf litter, and dung, and are important in the progressive breakdown of organic matter into their basic components to be returned to the soil, where they become available for plants. They also remove unhealthy and obnoxious materials from the landscape. Bow flies, carrion beetles, and skin beetles feed on dead animal tissue, skin, feathers, fur, and hooves and are of great importance in the removal of carrion from the environment. Dung beetles cut and shape vertebrate dung into balls that serve as a food source and a brood chamber for a single larva. Dermestid skin beetles feed on tissue and skin from vertebrate bones. Silverfish feed on dry organic debris and have a taste for paper, especially that containing starch or glue. Cockroaches and other insects are another example of scavengers that feed on dead plants and animals. Wood-boring beetles, termites, carpenter ants, and other wood feeders are important agents in facilitating the conversion of fallen trees and logs to soil.

Defensive behavior

Insects use many means of defense; these can be passive, where an insect relies on its appearance or location, or active, where an insect tries to escape, threatens a predator, or attacks it with chemical weapons. The habitat of numerous insects by itself provides them with a defense mechanism; insects that burrow into plant tissues or in the soil or live under rocks gain protection against predators. Some insects build a protective case or shelter that they carry around. Caddisfly larvae cement sand grains, small twigs and leaves, or other materials together to form the case inside which they live. Some chrysomelid beetles attach their feces to their backs to form a protective shield. Larvae of froghoppers use the excess fluid from the sap they suck to form a mass of bubbles that hides them from their enemies, and larvae of some psyllids construct a protective cover (a "lerp") of a sweet, crystallized substance called honeydew, under which they live.

Several beetles "play dead" when disturbed, dropping to the ground, folding up their legs, and remaining motionless for a while. Some insects blend with their backgrounds by closely resembling leaves, twigs, flowers, thorns, or bark. They are so well camouflaged in their normal surroundings that they become invisible to their predators in what is known as crypsis. In the forests of Papua New Guinea some weevils have modified wing covers that favor the growing of "miniature gardens" of mosses, lichens, algae, and fungi on their backs, which they carry around. The physical similarity with the surroundings is enhanced by the behavior of cryptic insects: inchworms freeze, holding their bodies upright like a twig, grasshoppers orient their bodies as if they were leaves, moths and walking sticks colored like bark remain immobile on their host trees.

On the contrary, the color patterns of several insects are striking in their attempts to intimidate predators or deflect their attention to parts of the body that are least vulnerable. This aposematic, or warning, coloration is found in several butterflies, grasshoppers, lanternflies, praying mantids, walking sticks, true bugs, and homopterans, among others. Some have brightly colored spots on the abdomen or hind wings that are hidden while the insect is at rest and are exposed suddenly when the animal is threatened. These flash colors may cause enemies to become startled, at least for a moment, allowing the insect to find a new hiding place and cover its conspicuous spots, rendering them invisible to the eyes of the predator. Other insects have a pair of eyespots on the upper surface of a pair of wings. If they are disturbed, they fully expose the wings with the eyespots. In some butterflies, this display is accompanied by a hissing or clicking sound produced by rubbing wing veins against each other and against the body. This behavior may elicit an escape response in birds, or else the attacks of birds may be directed at the eyespots and not at other, more vulnerable parts of the body. Other types of color advertisement, usually reds, yellows and blacks, are related to the palatability of the insect; predators associate a particular color with a bad flavor and learn to avoid insects displaying that color. Thus, the black and yellow of bees and wasps are associated with a sting and the red on a black or green background of certain butterflies is connected to a disagreeable taste. Several caterpillars show a striking color combination of yellow, orange, and green, usually associated with the presence of irritant hairs.

Some insects resemble or mimic other insects or even vertebrates. Predators learn to shun distasteful insects with striking colors, and certain insects take advantage of this behavior and avoid being eaten by displaying the warning color pattern of a distasteful or dangerous organism. A few noctuid moths move their legs in the manner of a bristly spider. Many beetles and true bugs mimic wasps not only in color but also in behavior, holding their wings upright, waving their legs and antennae, and bending the tips of their abdomens upward like wasps. The anterior part of the body of some swallowtail caterpillars is enlarged and painted with two eyespots, resembling the head of a snake. If the caterpillar is threatened, it will evert a scent gland that, besides producing an unpleasant odor, looks like the bifid tongue of a snake.

This kind of mimesis, where a harmless insect mimics a dangerous organism, is called Batesian mimetism. For example,

the South American butterfly Episcada salvinia rufocincta feeds on plants of the family Solanaceae and incorporates toxic substances (alkaloids) from its food plants, which make it distasteful to predators. Paraphlebia zoe is a damselfly that frequents the same forest clearings where the butterfly flies. Some males of the damselfly imitate the flight of the butterfly and have a white spot in the same position on the wings. Other males in the same population do not have any spots on the wings and appear invisible when they fly. There is also a form of Müllerian mimetism, in which an unpalatable or poisonous insect resembles another distasteful or harmful organism; predators learn to avoid only one color pattern, resulting in advantage to both mimic and model.

Many insects display an escape reaction when threatened, by flying, jumping, running, or diving. Certain noctuid moths detect the ultrasonic sounds produced by foraging bats and perform evasive actions by turning around, flying in zigzag patterns, or dropping to the ground and remaining motionless.

Chemical warfare provides defense for several types of insects. Numerous insects have repugnatorial glands, which secret noxious substances. Some of these secretions also act as alarm pheromones, warning other insects about the proximity of danger. Many cockroaches, stink bugs, beetles, ants, and walking sticks are capable of forcibly spraying an odoriferous secretion, sometimes for several feet. Caterpillars of swallowtail butterflies evert repugnatorial glands located behind the head, liberating a secretion that is effective against ants. The venomous secretions associated with the sting of wasps and bees and the bite of predatory true bugs also can be considered chemical defenses. Coccinelid, chrysomelid, lycid, lampyrid, and meloid beetles discharge blood when threatened, which is called reflex bleeding. In meloid beetles this blood contains substances that produce blisters or sores when it comes in contact with the skin of vertebrates.

Aphids, mealybugs, psyllids, whiteflies, and scale insects have developed a different defense strategy, in which they recruit ants as personal bodyguards. These insects produce a sweet secretion called "honeydew" that is attractive to ants. Thus, ants guard and tend colonies of aphids and aggressively attack any organism trying to feed on them.

Migration

Most species of insects disperse at some time during their life cycles in an attempt to populate new areas, though only a few have migratory mass movements similar to those of birds. In those insects with mass migrations, the movements usually are one way; one generation makes the trip in, and the following generation makes the return trip. Migration is accomplished mainly by flight, typically following the prevailing wind currents.

The best-known example of migrating insects is probably that of the monarch butterfly Danaus plexippus. After one or two generations in Canada and the northern United States, a combination of factors in the autumn, probably a shortening photoperiod and a drop in temperature, induces a generation of monarchs not to develop gonads and to migrate south to wintering places in California, Mexico, and Florida, where they congregate in great numbers on certain kinds of trees. In the spring they begin their journey back north, laying eggs along the way before dying. The subsequent generation completes the flight back, and the flight south of 2,000 mi (3,200 km) or more is repeated the following fall.

Swarms of migratory locusts have been known since biblical times. The migratory locust Schistocerca gregaria is known throughout the world for its mass migrations in which hundreds to billions of locusts swarm and advance, eating all vegetation in their sight. This species has two different phases. In its solitary phase the specimens are sedentary, selective in their food choices, and colored pale green or reddish, whereas in the migratory phase the specimens are gregarious, devour any kind of plant, and display contrasting colors. A young larva in either phase can be switch to the other one.

Not all migrating insects fly. Army ants (Eciton hamatum) migrate on the ground; army worms of the North American moth Pseudaletia unipuncta march onward, devouring every green thing in their path; and maggots of the mourning gnat Neosciara crawl in snakelike processions glued to each other in a slimy secretion, searching for an appropriate place for pupation in the forests of Europe.

Factors initiating migrations are not yet understood fully, but an onset of adverse environmental factors, such as crowding, lack of food, and short days, probably plays a part in the generation of endocrine changes leading to migration. For example, a sudden increase in population numbers may induce the production of winged forms in aphids that normally produce wingless forms, and this is correlated with the activation of certain hormone-producing organs.

Resources

Books

Evans, Arthur V., and Charles L. Bellamy. An Inordinate Fondness for Beetles. Berkeley: University of California Press, 2000.

Holldobler, B., and E. O. Wilson. Journey to the Ants: A Story of Scientific Exploration. Cambridge, MA: Belknap of Harvard University Press, 1995.

McGavin, George C. Bugs of the World. London: Blandford Press, 1993.

Preston-Mafham, K. Grasshoppers and Mantids of the World. London: Blandford Press, 1998.

Thornhill, Randy, and John Alcock. The Evolution of Insect Mating Systems. Cambridge, MA: Harvard University Press, 1983.

Organizations

Animal Behavior Society, Indiana University. 2611 East 10th Street, no. 170, Bloomington, IN 47408-2603 United States. Phone: (812) 856-5541. Fax: (812) 856-5542. E-mail: [email protected] Web site: <http://www.animalbehavior.org/>

Other

Journal of Insect Behavior [cited December 23, 2002]. <http://www.kluweronline.com/issn/0892-7553>.

Natalia von Ellenrieder, PhD