Territoriality
Territoriality
The advantages of territoriality
Territoriality is the behavior by which an animal lays claim to and defends an area against others of its species, and occasionally members of other species as well. The territory defended could be hundreds of square miles in size, or only slightly larger than the animal itself. It may be occupied by a single animal, a pair, family, or entire herd or swarm of animals. Some animals hold and defend a territory year-round, and use the territory as a source of food and shelter. Other animals establish a territory only at certain times of the year, when it is needed for attracting a mate, breeding, and/or raising a family.
The advantages of territoriality
Many different species exhibit territorial behavior, because it offers several advantages to the territorial animal. An animal which has a “home ground” can develop reflexes based on its surroundings. Thus it can react quickly to dangerous situations without having to actively seek hiding places or defensible ground. By spacing out potential competitors, territoriality also prevents the depletion of an area’s natural resources. This regulation of population density may also slow down the spread of disease. In addition, territorial behavior exposes weaker animals (which are unable to defend their territory) to predation, thereby promoting a healthy population.
Types of territories
Some animals will establish a territory solely for the purpose of having a place to rest. Such a territory is known as a roost, and may be established in a different area every night. Roosts are often occupied and defended by large groups of animals, for the protection offered in numbers. Individual personal spaces within the roost may be fought over as well. Roosting spots nearer the interior of a group of animals are often the safest, and therefore the most highly prized.
Several species of birds and a few mammals are known to establish specialized territories during the breeding season, which are used only to attract mates through breeding displays. This type of territory is known as a lek, and the associated behavior is called lekking. Leks are among the most strongly defended
KEY TERMS
Lek —An area defended by animals of one sex (usu-ally males) because ownership increases the chance of attracting members of the other sex.
Territory —An area defended by an animal against others, usually of the same species.
of all territories, since holding a good lek increases the chances of attracting a mate. Leks are generally of little use for feeding or for bringing up young, and the animals will abandon its lek once it attracts a mate or mates, or if it becomes too weak to defend it.
Defending a territory
Some animals will defend their territory by fighting with those who try to invade it. Fighting, however, is not often the best option, since it uses up a large amount of energy, and can result in injury or even death. Most animals rely on various threats, either through vocalizations, smells, or visual displays. The songs of birds, the drumming of woodpeckers, and the loud calls of monkeys are all warnings that carry for long distances, advertising to potential intruders that someone else’s territory is being approached. Many animals rely on smells to mark their territories, spraying urine, leaving droppings or rubbing scent glands around the territories’ borders. Approaching animals will be warned off the territory without ever encountering the territory’s defender.
On occasion, these warnings may be ignored, and an intruder may stray into a neighboring territory, or two animals may meet near the border of their adjacent territories. When two individuals of a territorial species meet, they will generally threaten each other with visual displays. These displays often will often exaggerate an animal’s size by the fluffing up of feathers or fur, or will show off the animals weapons. The animals may go through all the motions of fighting without ever actually touching each other, a behavior known as ritual fighting. The displays are generally performed best near the center of an animal’s territory, where it is more likely to attack an intruder, and become more fragmented closer to the edges, where retreating becomes more of an option. This spectrum of performances results in territorial boundaries, where displays of neighbors are about equal in intensity, or where the tendency to attack and the tendency to retreat are balanced.
Actual fighting usually only happens in overcrowded conditions, when resources are scarce. Serious injury can result, and old or sick animals may die, leading to a more balanced population size. Under most natural conditions, territoriality is an effective way of maintaining a healthy population. The study of social behaviors such as territoriality in animals may help us also to understand human society, and to learn how individual behavior affects human populations.
See also Competition.
David Fontes
Territoriality
Territoriality
Territoriality is the behavior by which an animal lays claim to and defends an area against others of its species , and occasionally members of other species as well. The territory defended could be hundreds of square miles in size, or only slightly larger than the animal itself. It may be occupied by a single animal, a pair, family, or entire herd or swarm of animals. Some animals hold and defend a territory year-round, and use the territory as a source of food and shelter. Other animals establish a territory only at certain times of the year, when it is needed for attracting a mate, breeding, and/or raising a family.
The advantages of territoriality
Many different species exhibit territorial behavior, because it offers several advantages to the territorial animal. An animal which has a "home ground" can develop reflexes based on its surroundings. Thus it can react quickly to dangerous situations without having to actively seek hiding places or defensible ground. By spacing out potential competitors, territoriality also prevents the depletion of an area's natural resources. This regulation of population density may also slow down the spread of disease . In addition, territorial behavior exposes weaker animals (which are unable to defend their territory) to predation, thereby promoting a healthy population.
Types of territories
Some animals will establish a territory solely for the purpose of having a place to rest. Such a territory is known as a roost, and may be established in a different area every night. Roosts are often occupied and defended by large groups of animals, for the protection offered in numbers. Individual personal spaces within the roost may be fought over as well. Roosting spots nearer the interior of a group of animals are often the safest, and therefore the most highly prized.
Several species of birds and a few mammals are known to establish specialized territories during the breeding season, which are used only to attract mates through breeding displays. This type of territory is known as a lek, and the associated behavior is called lekking. Leks are among the most strongly defended of all territories, since holding a good lek increases the chances of attracting a mate. Leks are generally of little use for feeding or for bringing up young, and the animals will abandon its lek once it attracts a mate or mates, or if it becomes too weak to defend it.
Defending a territory
Some animals will defend their territory by fighting with those who try to invade it. Fighting, however, is not often the best option, since it uses up a large amount of energy , and can result in injury or even death. Most animals rely on various threats, either through vocalizations, smells, or visual displays. The songs of birds, the drumming of woodpeckers , and the loud calls of monkeys are all warnings that carry for long distances, advertising to potential intruders that someone else's territory is being approached. Many animals rely on smells to mark their territories, spraying urine, leaving droppings or rubbing scent glands around the territories' borders. Approaching animals will be warned off the territory without ever encountering the territory's defender.
On occasion, these warnings may be ignored, and an intruder may stray into a neighboring territory, or two animals may meet near the border of their adjacent territories. When two individuals of a territorial species meet, they will generally threaten each other with visual displays. These displays often will often exaggerate an ani mal's size by the fluffing up of feathers or fur, or will show off the animals weapons. The animals may go through all the motions of fighting without ever actually touching each other, a behavior known as ritual fighting. The displays are generally performed best near the center of an animal's territory, where it is more likely to attack an intruder, and become more fragmented closer to the edges, where retreating becomes more of an option. This spectrum of performances results in territorial boundaries, where displays of neighbors are about equal in intensity, or where the tendency to attack and the tendency to retreat are balanced.
Actual fighting usually only happens in overcrowded conditions, when resources are scarce. Serious injury can result, and old or sick animals may die, leading to a more balanced population size. Under most natural conditions, territoriality is an effective way of maintaining a healthy population. The study of social behaviors such as territoriality in animals may help us also to understand human society, and to learn how individual behavior affects human populations.
See also Competition.
Resources
books
Parker, Steve, Jane Parker, and Terry Jennings. Territories. New York: Gloucester Press, 1991.
David Fontes
KEY TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- Lek
—An area defended by animals of one sex (usually males) because ownership increases the chance of attracting members of the other sex.
- Territory
—An area defended by an animal against others, usually of the same species.
Territoriality
Territoriality
A pattern of animal behavior, territoriality implies a fixed area (or territory) from which intruders are excluded by the owner through a combination of advertising, threatening, and attacking behaviors. It is important to distinguish between a territory and a home range , because the appearance of an outsider will elicit different reactions from the animal that lives in, or frequents, the area. Unlike an animal's marked territory, its home range is an area in which the individual roams about but the individual rarely defends it against other animals. There are some species, such as the breeding song sparrow, whose territory and home range are one and the same. In the majority of species, however, the territory tends to be smaller than the home range or the two areas overlap so that only part of the home range is defended as territory.
A question most often asked regarding the defense of a territory is: Why do owners usually win? In weighing the benefits versus the costs of defense, the owner is more likely to escalate the battle than the intruder because the owner has already invested in the area of conflict. The land is worth more to the owner not only because of familiarity with the area but also because the individual may be fighting to maintain exclusive access to the resources found on the territory. These resources may include one or more of the following: food, water, nest sites, and potential/current mates.
There are some costs of defense that the owner must assess as well. There may be time loss from other activities, such as foraging for food or mating. There is also an energy cost in defending an area. The signaling activities can be energetically expensive be they through continual chattering (e.g., squirrels), proclamations through singing (e.g., songbirds), or leaving scent marks at different points in and around the territory (e.g., bears). Further energy is expended in patrolling the perimeters and chasing off any animal that is getting too close to the boundaries or has crossed over into the territory. Finally, there is the risk of injury in battle with any intruder as well as a risk of predation as the owner focuses more on guarding and is therefore less guarded against attack.
There are three categories of territories: breeding, feeding, and allpurpose. The breeding territory is relatively small. It usually contains only a nesting or mating site. This type of territory is most characteristic of colonially nesting species that cluster nests at limited safe sites, such as in lekking or chorusing species where the males aggregate to attract females. The feeding territory tends to be larger than the breeding territory because it must contain sufficient food to support the owner of the territory and any mate or offspring that may also be residing there. Defense of the feeding territory is greatest during the nonbreeding season, because the individual's attention is more focused on the territory. The owner also becomes more vigilant during times when food is scarce. The cost of defense is worthwhile to the owner as it ensures the individual exclusive access of the area's resources. Finally, the all-purpose territory is generally the largest as it includes aspects of both breeding and feeding territories.
For all three of these types of territories, there are usually adjacent territories contiguous with an individual's proscribed area. The owner of a particular territory may have as few as two and as many as six neighbors with whom it shares common boundaries. The network of these contiguous territories is known collectively as a "neighborhood."
Territorial defense is generally employed only against animals of the same species, because animals of a different species will often inhabit a different niche within the same territory. In this manner, different species can coexist in the same area and not impinge on each other's food resources. Furthermore, there is no threat of the other animal stealing the owner's mate.
With the hierarchies that are found within communities, the territorial system comes into play as the stronger, more aggressive animal generally wins the better territory and maintains it against others. These systems have effects not only on an individual basis but also at the population level as well. If resources were allocated "fairly" to each member of a community or a species, then there actually may not be enough to sustain any one individual. (If resources become scarce because of a fire or drought, the individual may expand its territory in order to find sustenance.) This kind of division of territories, and thereby resources, would lead to population crashes. While it may be difficult to establish one's own territory, that kind of competition is necessary in order for the species to survive.
see also Foraging Strategies; Home Range.
Danielle Schnur
Bibliography
Alcock, John. Animal Behavior: An Evolutionary Approach, 4th ed. Sunderland, MA: Sinauer, 1989.
Bradbury, Jack W., and Sandra L. Vehrencamp. Principles of Animal Communication. Sunderland, MA: Sinauer, 1998.
Campbell, Neil A. Biology, 3rd ed. Berkeley, CA: Benjamin/Cummings, 1993.
Territoriality
Territoriality
The attempt by an individual organism or group of organisms to control a specified area. The area or territory, once controlled, is usually bound by some kind of marker (such as a scent or a fence). Control of territory usually means defense of that territory, primarily against other members of the same species . This defense, which may or may not be aggressive, typically involves threats, displays of superior features (e.g., size or color), or displays of fighting equipment (e.g., teeth, claws, antlers). Actual physical combat is relatively rare. A songbird establishes its territory by vigorous singing and will chase intruders away during the mating and nesting season. A leopard (Panthera pardus ) marks the boundaries of its territory with urine and will defend this area from other leopards of the same sex. Territoriality is found in many organisms, probably including humans, and it serves several purposes. It may provide a good nesting or breeding site and a sufficient feeding or hunting area to support offspring. It may also protect a female from males other than her mate during the mating season.