Hummingbirds

(Trochilidae)

Class Aves

Order Apodiformes

Suborder Trochili

Family Trochilidae

Thumbnail description
Small to very small birds, extensive metallic plumage, bill thin, extremely different in shape, feet tiny

Size
2–8.7 in (5–22 cm); 0.07–0.7 oz (1.9–21 g)

Number of genera, species
102 genera; 328 species

Habitat
Wide variety of habitats, arid zones, temperate, subtropical, and tropical forests, mountain regions to snow line

Conservation status
Endangered: 7 species; Critical: 8 species; Vulnerable: 12 species; Near Threatened: 7 species

Distribution
North, Central (including Caribbean islands), and South America

Evolution and systematics

Hummingbirds comprise a distinctive and most homogeneous group of New World birds. Although they form an undisputed phylogenetic unit, their relationship with other bird families is still debated. Traditionally trochilids are placed within the swifts (Apodiformes), together with the treeswifts (Hemiprocnidae) and the true swifts (Apodidae). This classification is mainly based on anatomical and morphological characters, such as modified cervical muscles, the skeleton of the flight apparatus, wing muscle innervation, or feather tracts. The question still remains whether these similarities are due to convergence or to common ancestry. This debate has led some classifiers to place hummingbirds in an order of their own, Trochiliformes. Recent biochemical studies favor the traditional classification: swifts and hummingbirds share a unique form of the enzyme malate dehydrogenase. This relationship is corroborated by the DNA comparisons of Sibley and his coworkers (1988). However, affinities to nightjars and their allies (Caprimulgiformes) based on patterns of feather growth (pterylosis), to mouse-birds (Coliiformes) from intestinal tract comparisons, and even to the songbirds (Passeriformes), derived from feather structure and egg-white protein analysis, have been suggested by various systematists. Here we follow the treatment suggested by Schuchmann (1999) and give hummingbirds the rank of a family (Trochilidae) comprising two subfamilies (the hermits or phaethornithines, Phaethornithinae; and the nonhermits or trochilines, Trochilinae) within the order Apodiformes. The taxonomic treatment used herein distinguishes a total of 102 genera and 328 species (subfamily Phaethornithinae: 34 species; subfamily Trochilinae 294 species) with over 680 subspecies.

Generic limits and species relationships within the trochilines are still poorly understood. Indeed, many non-hermit genera are based on the same characters that are used to define species. In recent checklists and classifications the lack of synapomorphies at the genus level in trochilines is expressed by over 50% of monotypic genera. All this taxonomic uncertainty presents a considerable challenge for future systematic research.

Despite this problem, several major clades have been identified among trochilines. Based on the variation of a single wing muscle, the Musculus tensor patagii brevis, three groups within the non-hermits have been proposed. The first unit covers those genera with a primitive muscle state: Androdon, Doryfera, Florisuga, Colibri, Anthracothorax, Eulampis, Chrysolampis, Polytmus, Topaza, and Heliothryx. A more advanced muscle state was found in the following genera: Campylopterus, Orthorhyncus, Stephanoxis, Lophornis, Discosura, Chlorostilbon, Cynanthus, Cyanophaia, Thalurania, Panterpe, Damophila, Lepidopyga, Hylocharis, Amazilia, Trochilus, Lampornis, and all Andean and North American taxa. The category "highly advanced" muscle state comprises members of the genera Calliphlox and Chaetocercus.

This single-character arrangement is surprisingly consistent when compared with morphological, morphometric, and behavioral information. Using these data sets, 11 distinct taxa can be clustered based on such characteristics as coloration, display and song structure, flight pattern, musculature, and nest structure and site. It should be noted that some of these genera are so closely related that their separate generic status is doubtful.

Patterns of tail-feather coloration, display and song structure, and a primitive cross-structure feature of the hindneck muscle (Musculus splenius capitis), place the "tooth-bills" Androdon and Doryfera at the base of the trochiline assemblage. They are followed by a more derived taxon containing the "sabrewing-and-mango" genera Campylopterus (including Phaeochroa, Eupetomena, Aphantochroa), Florisuga (including Melanotrochilus), Colibri, Anthracothorax (including Avocettula), Topaza, Eulampis, Chrysolampis, Orthorhyncus, Klais, Stephanoxis, and Abeillia. This assemblage is characterized by complex cervical musculature, similar patterns of song syntax, and small compact nests of little variation in form and structure, often placed on leaves or saddled on horizontal branches. Probably closely related to the "sabrewing-andmango" genera are the "coquettes" Lophornis and Discosura (including Popelairia), based on nest shape and male frontal display patterns.

The next taxon comprises the "true emeralds" Trochilus and Chlorostilbon (including Chlorestes). Biogeographical history and plumage feathers in both males and females already suggested close affinities between members of the West Indian taxa of Trochilus and Chlorostilbon, an assumption supported by a typical song pattern, exhibited during the male display, and also by similarities of nest structure and site. Based on the color patterns of the rectrices and other morphological features, their closest relatives are most likely the "emeralds" Panterpe, Elvira, Eupherusa, Goethalsia, and Goldmania, followed by the "woodnymph-and-sapphire" clade Cynanthus, Thalurania, Damophila, Lepidopyga, Hylocharis, and Chrysuronia. This latter assemblage shows distinctive cervical musculature, unique flight patterns in the male display, and nest structures with close affinities to the emeraldines. Another unit consists of the "amaziline emeralds" Leucochloris, Polytmus, Leucippus, Amazilia, Agyrtria, Polyerata, and Saucerottia. Typical nest forms, nest sites, and a cervical musculature pattern characterize this clade.

Another distinct taxon also derived from plumage comparisons are the "mountain gems" Microchera, Anthocephala, Lampornis, Basilinna (formerly treated under Hylocharis), and Lamprolaima. The "brilliants" Clytolaima, Heliodoxa (including Polyplancta), Hylonympha, and Sternoclyta comprise a further assemblage of closely related taxa. This group is united by typical morphological features like feathered upper and lower mandibles, throat coloration, song and display patterns.

The large "Andean clade" consists of five sub-units: the first contains Urochroa, Boissonneaua, and Aglaeactis; the second Oreotrochilus, Lafresnaya, Coeligena, Ensifera, Pterophanes, Patagona, and Sepahnoides; the third Heliangelus, Eriocnemis, Haplophaedia, Urosticte, and Ocreatus; the forth Lesbia, Sappho, Polyonymus, and Ramphomicron; and the fifth Oreonympha, Oxypogon, Metallura, Chalcostigma, Opistoprora, Taphrolesbia, and Aglaicercus. This arrangement is based on the following common features: open wing presentations after perching (especially members of the first, second, and third groups); distress calls; perching displays; advertisement songs; plumage characteristics; nest shape; and nest site.

Finally, another distinct assemblage, the "starthroat-and-woodstar" group, containing Heliomaster, Rhodopis, Thaumastura, Tilmatura, Doricha, Calliphlox (including Philodice), Microstilbon, Calothorax, Mellisuga, Archilochus, Calypte, Atthis, Stellula, Myrtis, Myrmia, Chaetocercus (including Acestrura), and Selasphorus. Some of these share similarities in plumage characteristics, notably an eclipse plumage; display pattern features; song structure; flight displays; nest shape; and nest-site.

During the period 1946–1995, 23 hummingbird species new to science were described—eight in Phaethornithinae and 15 in Trochilinae. After critical revision only one of the hermits, Koepcke's hermit (Phaethornis koepckeae), was considered a valid species, while only four remained on the list of trochilines, namely the royal sunangel (Heliangelus regalis), colorful puffleg (Eriocnemis mirabilis), and Perija (Metallura iracunda) and Neblina metaltails (Metallura odomae). The others turned out to be subspecies, hybrids, aberrant individuals, immatures, or synonyms of known subspecies. The Chiribiquete emerald (Chlorostilbon olivaresi) is considered a valid species but may in the future end up being treated only as a subspecies of the blue-tailed emerald (Chlorostilbon mellisugus), once more detailed information on geographical character variations are available and zones of contact within this complex are better understood.

Physical characteristics

Hummingbirds are extremely small. The majority of species are between 2.4 and 4.7 in (6–12 cm) in size and have a body mass of around 0.09–0.2 oz (2.5–6.5 g). The reddish hermit (Phaethornis ruber) from Guyana and Brazil and the Cuban bee hummingbird (Mellisuga helenae) weigh less than 0.07 oz (2 g), while members of the genera Eutoxeres, Ensifera, and Pterophanes are heavier than average at 0.42–0.49 oz (12–14 g). As its name suggests, the largest of all is the giant hummingbird (Patagona gigas) weighing 0.67–0.74 oz (19–21g), comparable in size to a swift.

Trochilids are highly evolved nectarivores, depending almost completely on the carbohydrate-rich sugar secretions (nectar) of ornithophilous flowering plants (approximate composition of diet being 90% nectar, 10% arthropods and pollen). They reach this liquid food with specialized tongues

and thin, elongated bills of various shapes, protecting their long and sensitive tongues. Their feeding behavior necessitates hovering flight, which allows them to remain apparently motionless in the air when feeding on exposed flowers, but due to this unique foraging behavior, they can no longer walk or climb with their feet, which serve only for perching. During hovering, their pointed, uncambered wings are moved mainly in the horizontal plane, describing with their tips a flat figure of eight, in the manner of a variable-pitch rotor. By slightly altering the wing angle, this technique allows all kinds of controlled forward, sideward, and backward movements in the air, including upside-down maneuvers.

While hovering, the wingbeat in smaller trochilids like the amethyst woodstar (Calliphlox amethystinus) averages 70–80 per second compared to 10–15 in the giant hummingbird (Patagona gigas). During the courtship flights of some North American trochilids such as the ruby-throated hummingbird (Archilochus colubris) and the rufous hummingbird (Selasphorus rufus) wingbeat rates of over 200 per second have been reported. The humming sound produced by the wings during hovering has given the family its English name.

Flying speeds under controlled laboratory conditions range roughly from 30 to 53 mph (48–85 kph). For the green violet-ear (Colibri thalassinus) in the wild a velocity of 60 mph (96 kph) has been recorded, and during short chase flights up to 93 mph (150 kph). The homing pigeon, one of the most skilful and rapid fliers among birds, travels at speeds of around 40 mph (64 kph).

The unique flight mode involves specific skeletal and flight muscle features. The deeply keeled and elongated hummingbird sternum is relatively large compared with those of other

flying birds. Eight pairs of ribs, two more than in most birds, help to stabilize the body during flight. Exceptional in structure are the strong coracoids of the pectoral girdle. Only hummingbirds and swifts have a shallow cup-and-ball joint where the coracoids are connected to the sternum. Tendons connect the flight muscles with the humerus.

The arm bones of all trochilids, consisting of the humerus, radius, and ulna, are much shortened, with a result that over 70% of the wing skeleton size is attributable to the elongated hand bones, homologous to the second, third, and fourth finger of the tetrapod hand. The hand bones bear 10 large flight feathers—the primaries—generally increasing progressively in size from the inner portion of the wing towards the tip. The modified humerus bone of hummingbirds moves freely at the shoulder joint, permitting optimal wing movement in all directions, including axial rotations of nearly 180 degrees. It is only the humerus that moves at this joint.

Hummingbirds use the upstroke and downstroke almost equally for powered flight, in contrast to most other birds, which mainly employ the downstroke for their powered flight. Both flight muscles together make up over 30% of the body mass of a hummingbird, much more than in other strong fliers such as migratory birds, in which these muscles account for about 20% of body mass.

As tiny endotherms, hummingbirds suffer from low thermal inertia and high heat loss. Flapping flight is energetically expensive, and convective cooling caused by wing and air movements can further exacerbate energy loss. Energy conservation during flight is thus an important physiological problem for hummingbirds. Studies by Peng Chai and his coworkers revealed that trochilids clearly use the heat produced in flight to contribute to their thermoregulatory requirements during hovering. Heat production by contraction of the flight muscles is employed as a substitute for regulatory thermogenesis to compensate for heat loss during exposure to cold.

Hummingbird flight muscles are extremely oxygen-dependent. Mitochondrial volume density in these muscles can account for 35% of their volume; this figure may represent an upper limit because any further increase would reduce space for the muscle fiber necessary for mechanical work. However, even during hovering, trochilids are operating within a reasonable physiological safety margin. These physiological reserves are essential for maintaining fitness parameters.

Another special trochilid muscle is the heart. It amounts to about 2.5% of their body mass. Wheras in small songbirds, like the house sparrow (Passer domesticus), it contributes 1.3% of the weight (only 0.5% in primates). A hummingbird's heart beats 500–600 times per minute while resting, and over 1,000 times per minute during aggressive encounters. In a ratite like the ostrich (Struthio camelus) the normal heart rate ranges from 40 to 180 beats per minute.

Hummingbirds' tails differ greatly in size and shape. They can be forked, V-shaped, rounded, or wedge-shaped. In several species of the genera Lesbia, Trochilus, and Thaumastura, for example, some of the tail feathers are strikingly elongated, the same length or even twice as long as the actual body size of the bird. Others, like Discosura longicauda and Ocreatus carry little flags at the end of a single pair of extended rectrices. A major feature of trochilid plumage is the striking iridescent colors of crests, gorgets, rectrices, and other feather structures. In contrast to colors generated by pigments, iridescence is of a physical nature, caused by the structure of platelets in the feather barbules. Beneath the upper surface of these platelets we find thin elliptical melanin bodies filled with air bubbles. These form a mosaic-like non-homogenous layer of up to 10, stacked one above the other within a barbule. C. Greenewalt discovered by electron microscopy that the thickness of the platelets influences not only the properties of the perceived light, but also those of the air held inside each pigmented body, thus causing variations in interference effects. Each pigmented body within a platelet can produce different colors depending on the angle from which it is viewed. Thus, a hummingbird's throat may appear metallic golden if a beam of light comes from directly behind the observer, but will shift to almost black if the angle of view is changed.

Hummingbird coloration is related to behavior. Generally two broad groups of coloration characteristics can be distinguished in birds: those promoting concealment and those enhancing conspicuousness. The majority of trochilid females exhibit a cryptic coloration, since all activities associated with nesting and the rearing of the young are carried out by the female alone. Conspicuous female coloration would easily betray the bird and the nesting site to potential predators. Males of many species of open habitats exhibit phaneric coloration, i.e., the opposite of cryptic. As part of their territorial and polygamous life-history, bright, light-dependent iridescent colors on throats, crests, or backs play an important role as visual threat signals for territorial defense, self-advertisement during display, or species-specific recognition cues. In forest-dwelling species, like most members of the Phaethornithinae, sex-specific phaneric iridescent coloration is absent, probably due to the dimly lit undergrowth of tropical forest habitats and to their non-territorial foraging behavior.

The plumage of male and female immatures is mainly similar to, but duller than, that of adult females. Immatures molt into adult plumage in their first year. In only a few sexually dimorphic species—like the Jamaican streamertails (Trochilus polytmus, T. scitulus) and the Juan Fernandez firecrown (Sephanoides fernandensis)—male and female nestlings can already be clearly separated by their plumage, which is similar to that of adults but less bright in coloration.

Hummingbirds have a single complete annual molt, starting soon after the breeding season. Replacement is slow and takes several months. Postjuvenile molt, which is absent in the Central American long-tailed hermit (Phaethornis longirostris, formerly considered as P. superciliosus) and possibly in other lekking tropical species, takes around four months, annual molt about four to five months. Molt of iridescent feather parts on throat, chin, forehead, and crown of males is often completed several weeks after renewal of primaries. It has been suggested that the delayed molt of brightly colored feathers ensures that the bird enters the subsequent breeding season in optimal plumage condition.

Nectar supplies the necessary energy for the highly evolved muscular system of trochilids. Hummingbirds take up nectar using their extendable biforked tongue, which is forced out of the bill by the hyoid apparatus stretched around the posterior part of the skull. The proximate half of the muscular tongue is partly cartilaginous. The distal half is divided lengthwise, forming two separate membranous curled troughs. This frontal part is essential in nectar drinking, since the liquid nectar is carried into the external troughs by capillary action. The rate of tongue licking varies from three to 13 licks per second. In nature, corolla curvature, position, and nectar volume are important factors in determining nectar extraction rate from flowers. As a general rule, hummingbirds drink their body mass of nectar in several hours. In order to meet their daily energy needs, hummingbirds must consume the nectar of about 1,000–2,000 flowers each day.

The first ornithologists to study hummingbirds supposed that the forked tip of the tongue had a sticky surface working as a glue to trap insects. However, this nectar-specialized feeding apparatus is completely unsuited for the capture of insects hidden inside flowers. Insects providing most of the protein in the hummingbird diet are either caught by hawking, or by gleaning from vegetation or spider webs.

Nectar also supplies the necessary energy for growth and renewal of body tissue, maintenance of body temperature at

104–107.6°F (40–42°C) (endothermy) and other important biological functions including reproduction. Since hummingbirds have the highest mass-specific basal metabolic rates of all birds, their digestive system is well adapted to break down food as quickly as possible and to absorb its nutrients.

Due to their energy-demanding hovering flight, hummingbirds have the highest oxygen requirements of all vertebrates. Their respiratory system, two compact symmetrical lungs for gas exchange and nine thin-walled air sacs acting as bellows for their ventilation, is adapted to utilize high gas volumes. At rest, the breathing rate is 300 times per minute, which may rise under heat conditions or during hovering flight to over 500 per minute, whereas a starling or a pigeon breathes roughly 30 times, and man about 14–18 times per minute.

Small endotherms like hummingbirds are under considerable time pressure; not only must they meet their daily food requirements, but they must also accumulate sufficient energy reserves to survive their nocturnal starvation. The following factors are therefore of decisive importance for extremely small hummingbirds: quality and accessibility of food, and mechanisms to reduce energy consumption. In trochilids, these mechanisms are long periods of inactivity between daily meals and torpor.

During torpor, gaseous metabolism and body temperature are adjusted to the levels of ambient temperature and regulated to remain within the range of 64.4–68°F (18–20°C). In torpor, hummingbirds become lethargic and incapable of reacting in a coordinated way to external stimuli. Energy savings during this immobile state are considerable; up to 60% of the total energy accumulated for the nocturnal resting phase. During observations on Nearctic migratory hummingbirds an irregular occurrence of torpor was noted. Birds reacted only with torpor when energy levels fell below lower limits during the night. According to these studies, torpor is an energy-regulating mechanism that is triggered below a threshold value, equivalent to a physiological regulation pattern coming into force in extreme conditions. As reasons for the irregularity of torpor, physiologists cite the risks and energetic costs of the lethargic state. The risks involved include the danger of predation while immobile, and insufficient residual energy for thermoregulation which could prevent awakening from torpor.

Laboratory research on Neotropical trochilids from a wide range of climatic zones and altitudes shows that in all species torpor occurs nocturnally. Regular occurrence of torpor has not been observed in Nearctic hummingbirds. An explanation could be that these trochilids enjoy long daylight conditions in their northern summer quarters (14–16 hours) during which to feed, resulting in a positive energy balance. Changes in levels of metabolism and body temperature only occur when the lower energy balance threshold is crossed.

Distribution

Hummingbirds are restricted to the New World. They reach their highest species diversity at tropical and subtropical latitudes in the montane zones of northern South America (Venezuela, Colombia, Ecuador, Brazil). Here, the species number reaches over 170 taxa. An abrupt decrease of species density can be observed on passing eastwards from the Andes to the extensive lowlands of that continent. A similar trend is seen at temperate latitudes in North America. Seven species of hummingbirds are found regularly in the western United States, whereas only one species, the ruby-throated hummingbird (Archilochus colubris), occurs in the eastern United States. Besides the west-east decrease of species richness, there is a general trend of species decline with increasing latitudes. At the northern and southern tip of both New World continents (Alaska and Tierra del Fuego) only one species exists. Hummingbirds in most temperate climate zones are migratory.

Habitat

Hummingbirds live in an extremely wide range of New World habitats. Some species—like the helmetcrests (Oxypogon) in western Venezuela and Colombia and the hillstars (Oreotrochilus) in Ecuador south to Chile—can be encountered at over 13,100 ft (4,000 m) on the verge of Andean snowfields and glaciers, where in wind-sheltered and sun-exposed canyons a relatively species-rich community of bird and insect-pollinated alpine flora flourishes. These high-altitude trochilids forage among dense stands of year-round flowering Scrophulariaceae, Asteraceae (Compositae), and Gentianaceae, which provide nectar and attract the insects that supplement their diet. Nocturnal frosts, occasional snowstorms, and daily temperatures of a few degrees above zero are the environmental conditions in these Andean regions. Helmetcrests and hillstars rarely leave this alpine habitat, except for periods of longer snow cover. Then they shift to the upper páramo, an open, grass-dominated vegetation with scattered stands of small trees and shrubs, only a few hundred meters below their native habitats. Often they leave the páramo plateaus again after a few hours and return to the rocky heights when weather conditions are favorable again. During frosty nights, trochilids of alpine Andean regions seek shelter in caves or under overhanging vegetation on the steep slopes. The members of these two hummingbird genera only are able to inhabit the extreme habitats of the high Andes on a regular basis. Here they are physiologically well adapted, reproduce successfully without facing strong competition for nesting sites and food from other trochilids, and, equally important, are not exposed to predation.

Penetrating drizzle, sometimes turning into snow, and a constant dense fog cover that leaves everything dripping wet, is the characteristic weather of the Andean páramos from Ecuador north to western Venezuela. Although grass tufts carpet the ground at these altitudes, numerous taller herbaceous plants form the typical landscape, like man-sized giant Espeletia species (Asteraceae), locally called frailejones, and terrestrial bromeliads of the genus Puya (Bromeliaceae). In addition, a large number of other herbaceous flowers and woody plants—belonging to many different families, like Rosaceae, Myrtaceae, Ericaceae, and Melostomataceae— often occur in wind-sheltered ravines. In this border zone between small patches of forest thickets and open páramo, over half a dozen trochilid species, including the genera Aglaeactis, Chalcostigma, Metallura, Ramphomicron, Lafresnaya, Eriocnemis, and sometimes Chaetocercus, occur year-round. During the major flowering period from the end of June to August, many more hummingbirds from lower elevations temporarily visit the páramos due to the superabundant nectar supply in the dense stands of angiosperms dependent on trochilids for pollination. Then large numbers of sparkling violet-ears (Colibri coruscans) from the lower Andean valleys, and occasionally, during warmer sunny days, even green hermits (Phaethornis guy) from the upper tropical rainforest may be encountered on the páramo. However, these species disappear in the afternoons, obviously returning to lower elevations again.

The mostly dry and windy puna zone of the Peruvian and Bolivian Andes is less favorable for hummingbirds than the northern wet páramo at similar altitudes. In the puna trochilids are much more confined to edges of Polylepis-Gynoxys woods and to sheltered gullies with bushy vegetation than to open grassland. The giant hummingbird (Patagona gigas) and the Andean hillstar (Oreotrochilus estella) occur regularly in the open grasslands of the southern high Andes mainly during the flowering period of the arborescent puya (Puya raimondii). A typical open puna species, the olivaceous thornbill (Chalcostigma olivaceum), frequently perches on grass tussocks from where it sallies for flying insects.

At 11,500 ft (3,500 m), the páramo and puna are sharply replaced by shrubs and trees of the upper Andean forest. Where these habitats merge, the hummingbird community comprises almost a dozen sympatric species foraging for nectar from a highly diverse angiosperm assemblage comprising many taxa of vines, shrubs, and woody plants with brightly red or orange-colored tubular flowers, a major visual cue for their minute avian visitors. From Venezuela to the yungas of Bolivia this life zone forms the upper distribution limit of the sword-billed hummingbird (Ensifera ensifera). Also occupying the same habitat is the great sapphirewing (Pterophanes cyanopterus), as well as other closely related long-billed allies from the inca and starfrontlet group (Coeligena), together with pufflegs (Eriocnemis) and sunangels (Heliangelus).

The most hummingbird-rich altitudinal region is the transitional zone between the Andean forest and the adjacent lower submontane forest, roughly between 5,900 and 8,200 ft (1,800–2,500 m). Here the daily temperature is fairly constant, ranging from 53.6° to 60.8°F (12–16°C). Daily cloud cover, especially in the afternoon, brings the moisture that sustains a rich plant life of ferns, shrubs, trees, vines, and especially ephiphytes, like orchids, bromeliads, gesneriads, and ericads. As diurnal endotherms, trochilids are the most successful organisms serving the cloud forest plants as pollen vectors. At these altitudes, heterothermic insect pollinators are dependent on favorable temperature and weather conditions, which limits their flight activity to a few, often unpredictable daytime hours.

Although there is some flowering seasonality among ornithophilous plants of different families like Ericaceae and Rubiaceae, this Andean life zone between 12° north and south of the equator provides abundant nectar year-round, allowing the coexistence of over a dozen hummingbird species. The cloud forest trochilid community comprises a concentration of very small to medium-sized and large species from about 0.1 to 0.42 oz (3–12 g) with diverse bill shapes and sizes. Alongside a group of 14 core species another 10–15 hummingbird taxa—including lowland and high Andean species— may be found in the cloud forest during the peak of the flowering season, attracted by the nectar-rich ericad shrubs and Inga trees.

The tropical lowland forests of South America, in stark contrast, harbor a much impoverished hummingbird community. Dominant species of this life zone mostly belong to the subfamily Phaethornithinae (Androdon, Eutoxeres, Glaucis, Threnetes, and Phaethornis), whereas trochilines are normally represented by the genera Amazilia, Polyerata, and Agyrtria (Amazilia tzacatl, P. rosenbergi, west of the Andes; Agyrtria versicolor, P. fimbriata, Agyrtria leucogaster, east of the Andes), and Hylocharis (H. grayi, H. eliciae, west of the Andes; H. sapphirina, H. cyanus, mainly east of the Andes). Cis- and trans-Andean hummingbird taxa often constitute allospecies of a superspecies with almost identical ecological requirements. A fine example is provided by the two tropical lowland species of the genus Heliothryx, separated in their distribution by the Andes.

Hummingbirds occur in many other life zone including arid-scrub (Lucifer hummingbird, Calothorax lucifer; Peruvian sheartail, Thaumastura cora), desert oases (oasis hummingbird, Rhodopis vesper), Nearctic pine forests (many North American species: broad-tailed hummingbird, Selasphorus platycercus; magnificent hummingbird, Eugenes fulgens), mangrove swamps (mangrove hummingbird, Polyerata boucardi), and on remote islands in the Caribbean (Trochilus, Chlorostilbon, Eulampis, Mango, Orthorhynchus) and on the Juan Fernández Is. off Chile (green-backed firecrown, Sephanoides sephaniodes; Juan Fernandez firecrown, S. fernandensis). However, many of these habitats are occupied only sporadically for a short period or seasonally during the breeding period, when food-plants are in flower. Birds leave these regions again when conditions become unfavorable. Many of the North American trochilids then disappear and migrate to their Central American winter quarters. The same is true for the green-backed firecrown (Sephanoides sephaniodes) from Chile, which leaves its southernmost summer range on Tierra del Fuego to migrate northwards to western Chile and Argentina. On larger islands, hummingbirds show altitudinal migration or disperse to different lowland habitats.

Trochilid habitat requirements are still poorly understood. Many species exhibit a remarkable plasticity, easily adapting to man-made habitat changes, or even expanding their ranges if food conditions are favorable (Anna's hummingbird, Calypte anna). Others rapidly decline in numbers (hook-billed hermit, Glaucis dohrnii) and face extinction following environmental disturbance. Besides habitat changes, cases of competition for food from congeners must be thoroughly analyzed in the future to better understand hummingbird community structure and change, an important prerequisite for successful conservation programs.

Behavior

Physiological adaptations for nectar feeding, and energy regulation patterns resulting from limiting temporal and environmental conditions are fundamental factors for understanding of the general habits of hummingbirds. The utilization of energy-rich nectars most likely fostered strong individual competition for this food source, favoring the evolution of specific maintenance and survival strategies. As a general consequence, males and females of almost all hummingbird species so far studied are solitary, often aggressively defending nectar sources like flowering shrubs and trees against any potential food competitor. The sexes are polygamous and associate only briefly to fertilize the eggs.

Mainly the males of species with bright iridescent colors establish feeding territories at flowering bushes that allow them to cover their daily energy needs. In order to defend their nectar resources they often perch high on nearby exposed branches. These serve as a vantage point from which predators can be detected with ease or from which the area can be defended against possible intruders, including females, by vocal warning signals and agonistic flights. Often the territory holder first empties the nectar from peripheral flowers to remove or reduce the feeding reward for newly arriving competitors. Trespassers ignoring the threat calls of the territory owner are robustly attacked in flight, sometimes resulting in direct physical combat. An airborne fighting pair may then be locked in strong claw grips, tumbling to the ground like a falling stone. These fights are rarely harmful to the birds but occasionally small featherless dorsal parts can be seen as a result of such aggressive encounters.

Purple-throated carib (Eulampis jugularis) males react differently to territorial intruders and food competitors during the reproductive period. All but their mates are aggressively chased out of the defended feeding area. Incoming females,

however, are guarded and allowed to feed prior to mating. A similar function of the feeding territory has been observed in the tiny dimorphic white-rumped green thorntail (Popelairia conversii) by K.-L. Schuchmann. In December to March, during the breeding period of the species, Inga trees begin to flower in southwestern Colombia. Then the males establish and defend feeding territories in these forest giants. Females entering these feeding grounds are allowed to feed on the nectar-rich brush-like white flowers of the trees. Frequently, males display to individual females and copulate with them while they are in their territory. Green thorntail males aggressively attack all possible territory intruders, even much larger trespassing birds like the numerous tropical kingbirds (Tyrannus melancholicus) gathered around flowering Inga trees. Besides females of the green thorntail, a small diurnal moth, the white-banded sphinxlet (Aellopos titan), similar in size, appearance, and flight behavior to the white-rumped hummingbird, visits the guarded territories. Being almost perfect female mimics to male hummingbirds, they are obviously considered as potential mates, as indicated by the displays directed at them. However, because of their fast and unpredictable flights within the densely packed Inga flowers, green thorn-tail males quickly lose interest in these female mimics but still continue with their mate-defense behavior. Hummingbird males direct their agonistic flight maneuvers especially at tropical kingbirds, which prey on the white-banded sphinxlet. When hummingbird males were excluded from a flowering Inga, predation rate on the moths was over 80%, and individual moths spent only one to three seconds at each flower. When such an Inga tree was guarded by a green thorntail, male sphinxlet predation by kingbirds declined to 20% and most moths spent four to six seconds feeding at each flower visited. In the latter case, Inga seed production was significantly higher than in a territory without a hummingbird guard. This mimicry relationship between two different animals, a moth and a hummingbird, is an instructive example of the complex interrelated webs of adaptation in the tropics.

Females of a few hummingbird species may hold temporally and spatially limited territories around localized feeding sites during and after the reproductive period. Studies by J. Dorst, K. B. Armitage, and M. L. Cody looked at females defending a nest area or birds on migration defending a small area in a locally common food source. However, long-term feeding territories are known only for the brightly monomorphic fiery-throated hummingbird (Panterpe insignis) in southern Central America. This type of territoriality reflects the temporal and spatial decline of nectar resources and the resident status of the birds. L. L. Wolf, who has studied female territorial behavior of Panterpe insignis in Costa Rica, suggests that territoriality in hummingbirds is accompanied by strong selection for sexual monomorphism in plumage coloration (advantageous in aggressive encounters) and for sexual similarity in bill length (advantageous for efficient utilization of limited food resources).

Many species in tropical Central and South America do not establish feeding territories but are trapline feeders on flowers often too scattered to be defended. But between territoriality and trapline behavior many more intermediate feeding strategies can be found, depending on flower dispersion, morphology, and nectar reward.

Despite being under extreme pressure to gather energy quickly, and having developed many obvious behavioral traits for doing so, hummingbirds spend over 70% of their daily activity phase perched, apparently doing little else besides singing, self-preening, and sunbathing. Hummingbirds bathe several times a day. Some sit in shallow water and splash like sparrows, others cling to rocks beside waterfalls gathering moisture and spray from above, vibrating their wings and ruffling their body feathers. Hermits and many trochilines hover just above gently flowing forest streams then abruptly drop into the water, sometimes almost completely submerging their body. These dives are sometimes repeated over several minutes.

Hummingbirds do not show flocking behavior. Individual social contacts are rare but occasionally do occur around superabundant nectar sources and at cave roosting sites (Andean hillstars, Oreotrochilus). Nest aggregations within a few meters are known for the cave-breeding Ecuadorian hillstar (Oreotrochilus chimborazo) and within a 66–100-ft (20–30-m) radius for the Costa hummingbird (Calypte costae), Bahama woodstar (Calliphlox evelynae), rufous-tailed hummingbird (Amazilia tzacatl), and crimson topaz (Topaza pella).

Hummingbird foraging behavior is determined to a large extent by individual perception and memory capability. Field and laboratory studies by G. H. Pyke, conducted with North American broad-tailed hummingbirds (Selasphorus platycercus) and rufous hummingbirds (S. rufus), suggest that these hummingbirds may at least perceive and remember the number of flowers available on an inflorescence, the number of flowers already probed on the inflorescence, and the amount of nectar obtained at the present flower.

Many hummingbirds are already active before dawn and late after sunset. Remarkable examples are the incas and star-frontlets (Coeligena) which visit flowers in the early morning hours when it is still dark. Other species still continue to forage for nectar in the evening twilight before disappearing to their roosts. Although hummingbirds are not nocturnal, the night vision of some taxa seems to be excellent.

Ornithologists have discovered trochilids at their roosting sites on only a few occasions. Their sleeping places are sometimes well protected by leaves, as in the rufous-tailed hummingbird (Amazilia tzacatl), whereas the long-billed starthroat (Heliomaster longirostris) roosts on the thin exposed twigs of tree-tops. The sleeping position of perching trochilids is strikingly similar in all species observed: with both feet on the perch, head exposed, neck retracted, and the bill pointed forward and upward. By contrast, songbirds on their roosting sites cover their turned-back head with their shoulder feathers and often perch on one foot.

Hummingbirds are threatened by only a few predators among vertebrates. Camouflaged snakes on Heliconia flowers prey on them when they are foraging for nectar or when brooding. Forest-falcons occasionally capture hermits at their lek sites, pygmy-owls may attack them at dawn when still visiting flowers. Nest robbers like jays, toucans, and possibly some bats, however, seem to be the major predators. This information has been generated only by the occasional observation, and the impact of predation on hummingbird populations is almost completely unknown. Whenever a potential enemy is sighted by a hummingbird it is directly approached by rapid diving attacks accompanied by a series of high-pitched warning calls. These alarm signals regularly attract other bird species, which join in the aggressive flight encounters supported by continuous mobbing noises. Threat behavior like flight attacks are exhibited especially by hummingbird females against intruders near their nesting sites, even if they are not potential predators.

Feeding ecology and diet

Virtually thousands of New World plant species rely exclusively upon hummingbirds for pollination. As a consequence of the year-round high energy requirements of trochilids, plants that are pollinated by hummingbirds provide nectar at all times of the year, creating the opportunity of a phenological displacement of flowering times as a means of reducing interspecific pollen flow.

The evolutionary relationship between hummingbirds and their food plants is a good example of close mutualism, resulting in many adaptations between flower and pollen vector, called the syndrome of ornithophily. Plants that have converged upon the "hummingbird" syndrome bear relative large flowers, solitary or loosely clustered, often placed in a horizontal or pendant position. Typical hummingbird plants open their blossoms during the day, flowers are generally brightly colored—often red, orange, or yellow, sometimes in combination with contrasting white corolla parts. Exceptions can be found in the Gesneriaceae, where some ephiphytic species exhibit solitary inconspicuous whitish flowers. However, hummingbirds are attracted to these well-camouflaged flowers by ornamental red-edged or red-centered leaves, a little studied advertisement strategy in hummingbird pollinated plants, known as phylo-flagging.

Some of the more commonly known hummingbird-pollinated New World plant species belong to the genera Zauschneria (Onagraceae), Delphinium and Aquilegia (Ranunculaceae), Mimulus (Scrophulariaceae), Aphelandra (Acanthaceae), Centropogon (Lobeliaceae), Cavendishia (Ericaceae), Columnea (Gesneriaceae), Psitticanthus (Loranthaceae), and Heliconia (Heliconiaceae). Most ornithophilous plants are dicotyledons with perennial herbs and shrubs. Only a few New World trees are pollinated by hummingbird. Flowering trees with a very large nectar source, like many Erythrina species, are quickly occupied by territorial hummingbirds remaining in the tree tops for the whole flowering period until the nectar source declines. By doing so, pollen flow is extremely reduced. The corolla of a typical hummingbird flower is often long, thickened, tubular in shape, and scentless. It contains sucrose rich or sucrose dominat nectar which is exploited by trochilids in hovering or hover-clasping flight.

Hummingbird flowers supply their pollinators with large amounts of nectar per flower and day, but do not satisfy their nutritional requirements at one visit. However, P. Feinsinger discovered in a Costa Rican heliconia (Heliconia psittacorum) that only some flowers contain abundant nectar (bonanzas), some essentially none (blanks). Since hermits are the main pollinators of heliconias, Feinsinger suggested that these hummingbirds must visit many flowers in order to encounter one with high nectar content, thus the bonanza-blank pattern may support cross-pollination in H. psittacorum. In another field study on the pollination of successional plant species in the cloud forest at Monteverde, Costa Rica, Feinsinger observed that flowering was staggered among plant species, resulting in a constant nectar supply to trochilids. In five plant species that were closely investigated, measurements of nectar volume indicated that the bonanza pattern was evident. He concluded that plants may conserve energy by producing large numbers of nectarless flowers and a few bonanza flowers. By doing so hummingbirds are forced to visit many flowers to meet their energetic needs. By visiting many flowers, cross-pollination is promoted.

An obvious feature of most bird pollinators in relation to insects is their larger body mass. This, combined with endothermy increases the energy requirements of trochilids. Only a few species of large hawkmoths have higher energetic needs when active than hummingbirds, but reduce their metabolism like other insects when weather conditions are unfavorable. Hummingbirds use nocturnal torpor for short-term

energy savings, remaining active even under inclement conditions during the day when insects are inactive. Trochilids are thus more reliable pollinators where cool or rainy conditions occur regularly. Hummingbirds, like other nectarivorous birds, forage throughout the day, with higher activities at dawn and dusk, although a small fraction of each hour may actually be spent feeding. Insects search for nectar only at certain periods during the day. Due to their high body mass, hummingbirds also have much higher potential mobility than most insects. A long-lived pollinator, such as a hummingbird, experiences several flowering seasons during its life span. These birds can easily remember flower stands of local or patchy distribution, and, thus, the floral environment for trochilids is much more differentiated in time and space than for insects.

There is a close fit between shape and length of the bill of some hummingbirds and the flowers on which they feed. Like the insect feeding apparatus, bird bills are evolutionary labile (readily undergoing change) structures. Selective forces have had a much stronger impact on morphological coadaptations between bird bills and flower shapes than between snout structures of bats and bat flowers. This may generally explain the higher species diversity of flower-visiting birds and insects compared to bats.

Bill structure and shape, which varies widely among trochilids, largely influences the efficiency with which they forage at each flower and determines the type they can successfully exploit. Hermit hummingbirds (Phaethornithinae) and certain species of trochilines (Trochilinae) have long straight or long and slightly decurved bills providing access to long-tubed flowers, rich in nectar. At the other extreme, many trochilines have short, straight bills allowing them to opportunistically exploit a variety of moderate to insect flowers. However, some short-billed species like Heliothryx are nectar robbers, taking nectar from flowers by piercing the corolla base.

In more complex tropical environments hummingbird communities may grouped, according to required power, into different foraging modes. "High-reward trapliners" with specialized long bills (almost all hermits, some non-hermits) visit widely scattered long-tubed and nectar-rich flowers following a repeated foraging circuit (trapline). "Low-reward trapliners" have smaller straight bills, visiting dispersed but less specialized flowers. "Territorialists" occupy "clumped moderate" (flowers with small to medium corollas and little nectar reward) and "clumped rich" (flowers with long corollas and high nectar production that occur in dense clumps) flowers. These are generally small hummingbirds with short bills and a moderate to high required power. They defend feeding territories against any potential hummingbird intruder. "Territory-parasites" frequently occur in "clumped moderate" flowering stands, parasitizing the territorial holder. These parasitizing trochilids may be large with medium-sized bills, high required power output, ignoring aggressive displacement displays by the territorial bird, or they may be very small, resembling large insects like Lophornis and Atthis, feeding at sections of a territory which are not directly visible or not regularly inspected by the resident bird. "Generalists" have short to moderate bills and small to medium body mass with moderate required power output. They behave opportunistically, switching feeding from dispersed moderate flowers to clumped flowers. Frequently these generalists are also called "faculative trapliners" since they may switch to lowreward traplining depending on the local nectar availability and competition for food.

A closer examination of the mutualistic relationship between hummingbirds and their food plants has shown that pairwise coevolution between a certain trochilid species and a certain plant species is non-existent. Plant-bird mutualisms are best described as having originated by "diffuse coevolution," in which hummingbird pollinated plants and trochilids are represented by an array of populations that generate a selective pressure as a group.

Hummingbirds in North America and Colombia have been observed to make use of sapsucker pits in living trees consuming the sugary sap and catching insects attracted to this food source. Especially Archilochus colubris from North America seems to benefit from these sugar sources during spring migration when plants just begin to flower.

Hummingbirds complement their nectar food with some pollen gathered when drinking nectar. Although nectar contains fragments of essential amino acids, the major protein supplement comes from arthropods. It has been noted that hermits differ from non-hermits with regard to higher insect consumption, but this idea is not supported from laboratory and field studies. F. G. Stiles concluded from his detailed field study in Costa Rica that there is no support for considering hermits to be more insectivorous than non-hermits. As a general approximation most hummingbirds consume a daily ratio of nectar to arthropods of roughly 9:1.

Hermits, which exclusively live in the understory are hover cleaners, specialized in collecting web spiders. Threnetes ruckeri forages for jumping spiders. The exception among the hermits seems to be Eutoxeres aquila which hawks for flying insects. In most trochilines hawking for flying insects is a common foraging mode. Flies and wasps are the dominant prey, but spiders, ants, and small beetles also have been found in the stomachs of non-hermits.

There is no evidence that hummingbirds can extract arthropods from flowers with their bills. Insects do not stick to their tongue. It is more likely that selection for nectar drinking was the major evolutionary force in the developement of a hummingbird's feeding apparatus, and that bill morphologies in turn constrain arthropod foraging tactics.

Reproductive biology

Hummingbird males are polygynous, mating with several females during a reproductive period. In most species studied the male associates with the female only during a short period to fertilize her eggs. All remaining reproductive responsibilities like nest building, incubation, and rearing the young are carried out solely by the female. There are a few reports of males participating in incubation or feeding young, but whether these observations are accurate, random exceptions, or regular species-specific behavior still needs further investigation.

Interactions between hummingbird males and females are normally restricted to the short period of sexual synchronization. Males advertise themselves by song, iridescent plumage (Trochilinae), and aerial flights either at traditional display grounds, or leks, from dispersed singing posts, or at their feeding territories where they are visited by females when receptive to copulation. The male behavior for attracting females is similar to the defense display directed towards food competitors, predators, or any intruder to the feeding ground. By specific behavioral triggers, mainly perching motionless near an advertising male, the female switches the agonistically orientated display of the male into one which is sexually directed and leads to copulation. Thereafter both sexes separate again. Males of the fiery-throated hummingbird (Panterpe insignis) and purple-throated carib (Eulampis jugularis), among others, show a resource-based mating system, allowing conspecific females to enter their otherwise aggressively defended territories to feed on nectar-rich flowers. Females may copulate with males on these feeding grounds or may collect nectar for themselves or their offspring during the period of reproduction. In hillstars (Oreotrochilus) only females hold territories, on which they are visited by males in the breeding season.

The onset of breeding in hummingbirds is very variable from species to species and from region to region. As a general rule the peak reproduction in most trochilids is closely associated with the months of mass-flowering of many ornithophilous flowering plants. In the high Andes of Ecuador, violet-ears (Colibri), metaltails (Metallura), trainbearers (Lesbia), and pufflegs (Eriocnemis) begin to breed during most of the wet season often around mid-October and continue to March, sometimes to April. At similar altitudes further north or south the onset of reproduction starts about three months earlier or three months later than in the mountain regions near the equator, the breeding season often lasting only a few weeks. At lower altitudes, seasonality of the reproductive cycle declines and nests of several species may be found throughout the year, with decreasing numbers during the peaks of the dry and wet season; these seasons differ greatly from region to region. North American trochilids (Selasphorus, Archilochus, Calypte costae, Calothorax, Stellula, Eugenes, and Lampornis) chiefly breed during spring to late summer, with the exception of Anna's hummingbird (Calypte anna), which generally nests during winter, probably as a strategy to avoid competition with other temperate trochilids that invade the coastal Californian scrub zone (chaparral) during the spring flowering peak of several nectar-rich food plants.

Females of many Trochilinae select nest-sites after a nearby rich nectar source has been located. Suitable branches for nesting are first inspected by hovering above the surface and touching down over the spot repeatedly. Nest-sites of hermits (Phaethornithinae) are not associated with nearby food sources. Females of this subfamily frequently cling with their feet to suitable green leaves of palms or Heliconia stands to which they later attach their cone-shaped nests. This behavior may serve to test the strength of the stratum for the purpose of nest construction.

Hummingbird nests are tiny and of various shapes, and are placed in a wide range of heights, locations, and substrates. Most nests are of a cup-like architecture, saddled on branches and large leaves (Anthracothorax, Florisuga), placed in forked twigs (Thalurania), glued to rocky walls (Oreotrochilus), hidden underneath a bulk of dense thickets overhanging a slope (Eriocnemis, Lesbia), attached to lianas (Heliothryx), or fastened beneath a pendular leaf which provides shelter from rain (Haplophaedia, most Phaethornithinae). Some genera like the sylphs (Aglaiocercus) construct completely domed nests, while others like the metaltails produce semi-domed nests.

Nests can be found at all heights, from a few inches above the ground (Phaethornis) to tree-top levels at 33–100 ft (10–30m) (Anthracothorax, Eulampis, Heliomaster, Eugenes). Even within a species nest-sites may vary from low secondary vegetation to the canopy. Nests are commonly placed in locations giving some protection from direct sun and rain by overhanging leaves. For nest-site selection balanced micro-climatic conditions, like temperature and humidity, seem to be a major prerequisite for ensuring the successful development of the embryos. Thus nests are often located near waterfalls, forest streams, or lake shores. The nest construction process lasts around five to ten days for most species studied.

Many hummingbirds decorate the outer wall of their nest with pieces of lichen, moss, dead leaves, rootlets, bark, and so on, making it almost indistinguishable from the immediate surroundings and thus difficult for predators to locate. Soft and fine plant materials, occasionally small feathers or animal hair, are used for the inner nest lining, providing optimal insulation during incubation. Among the exceptions are nests of high-altitude hummingbirds, like the sapphirevented puffleg (Eriocnemis luciani), in which the inner soft cup layer is absent.

Members of the genus Phaethornis construct compact pendent nests of soft plant fibers and spider web attached to the inner side of elongated plant leaves. All other hermit genera build similar but loose nests with open walls of coarse material like stiff rootlets or dry pieces of leaves and liverworts. This nest structure is an adaptation to the wet lowland forests where most hermits occur, and the poor insulation provided by the coarse nest material is largely compensated for by the warm ambient lowland temperature.

Often nesting material is reused in a new nest or the old nest serves as a platform for a subsequent construction. Females repair nests regularly, especially during the incubation period. The clutch of all hummingbirds consists invariably of two eggs, which are white, non-glossy, and of elliptical oval shape. In hermits (Glaucis, Threnetes), nests with three or four eggs have been frequently observed, but these are apparently attributable to more than one female, so-called egg-dumping. Females of both genera regularly inspect active nests of conspecifics. Occasionally three eggs have also been found in the nest of a few trochilines (Colibri, Amazilia, Calypte), and again it is most likely that the additional egg was laid by another female. Eggs are usually laid in the early morning. Normally there is a two-day, rarely a one or three-day interval before the second egg is laid. Eggs are sometimes laid before the nest is completed; females then continue construction between incubation intervals. Incubation may begin when the first egg is laid but regular incubation starts with the second.

Hummingbird eggs are naturally very small. Eggs of the tiny bee hummingbird from Cuba (Mellisuga helenae) average 0.4 × 0.3 in (11 × 8 mm), those of the much larger giant hummingbird (Patagona gigas) of the Andes have a size of 0.8 × 0.5 in (20 × 12 mm). Two eggs of a small species—like the reddish hermit (Phaethornis ruber)—equal roughly 35% of female body mass, while for the giant hummingbird the figure is about 15%. The severe energy constraints on females of small species may explain why single annual broods are much more common in these species than in medium- to large-sized taxa.

The incubation period for the majority of trochilids lasts 16–19 days, about two to five days longer than in songbirds. The shortest periods are known for the white-eared hummingbird (Basilinna leucotis) from Central America with 14–16 days, whereas hillstars and other high Andean species can attend their clutch for 22–23 days.

For the few species studied in detail females incubated 75–90% of daylight hours. How do these birds, which normally consume nectar every 6–10 minutes, meet their energy requirements during this prolonged stationary period? A closer look at the thermoregulatory ability of incubating females reveals that they compensate for a reduced food intake during long attentive periods by reducing their body temperature from 105.8°F (41°C) to about 89.6°F (32°C), resulting in energy savings of almost 50% during the day.

Depending on the onset of incubation, eggs may hatch at intervals of 48 hours or almost synchronously. Hatchlings of all hummingbirds are altricial: nearly unfeathered, blind, and helpless. During their long nestling period of 23–26 days, in high Andean trochilids 30–40 days, the following three well-differentiated morphological stages of development can be observed.

During Stage One—from day one to about day five after hatching—the nestling is nearly naked and its eyes are still closed. The chicks are inactive in the nest and are fed regurgitated food by the female.

Stage Two extends from day six to day nine and is the period of major feather development on wings, tail, and back.

Stage Three covers day 10 until fledging at around 17–19 days. By this time chicks are almost completely feathered and often sit on the edge of the nest facing outward.

Because hummingbirds forage while hovering they can no longer climb with their feet, which serve only for perching. Consequently, they build exposed but camouflaged nests easily accessible in flight. The often exposed nest-site and low reproductive output probably favored the development of a very specific gape-response behavior. Loud begging calls of the offspring, as well as uncontrolled begging and gaping movements through non-specific causes like vibration of nest by wind, are behaviors that could potentially betray the nest-site to predators such as tree lizards, snakes, and birds. Thus the highly specific stimuli (the female touches the chick behind the eye bulge with her bill) which elicit gaping by unfledged hummingbird chicks are most likely adaptations for reducing predation on exposed nest-sites. Also as part of a predator-avoidance strategy female hummingbirds never approach the nest directly. They often fly to the nest-site in fast semi-circles and/or zigzag maneuvers.

Hummingbird females feed their young throughout the day around twice per hour and brood them until an age of 7–12 days. Hummingbird nestlings grow quickly, reaching almost 80% of their adult mass within 10–12 days. At an age of 15–18 days, a few days before fledging, nestlings are much more active in the nest, preen their plumage for extended periods, and look around with interest when other birds or the parent is near the nest.

After leaving the nest the young are fed by the mother for 18–25 days, in some tropical genera like fairies and sylphs occasionally for up to a month. Juveniles do not follow their foraging parent but remain in a special place for several days, often high up in the tree-tops, where they are fed by the female. When flying well, often shortly after the fifth day of fledging, the female prolongs the feeding intervals, teaching the young by loud calls to come for food wherever she wants to feed them. By doing so the juveniles learn quickly to follow the parent bird to her feeding grounds in flowering shrubs, vines, or trees. Foraging for nectar is the next step for the young to learn, mainly achieved by observing the adult at close quarters when sampling nectar. However, this period of learning to choose the right food is often based on trial and error. Several days before juveniles achieve independence they show mutual agonistic behavior, often attacking each other with their feet, trying to prevent the brood-mate from being fed. Between feeding bouts, young hummingbirds are often seen to probe on twigs or red parts of leaves that resemble a flower in shape and color. This exploratory behavior is maintained throughout adolescence and leads them to new nectar sources.

Hummingbird females may successfully rear two broods in a season. In some North American species nest building and even incubation has been observed while the female was still attending nestlings in her first nest. For several tiny tropical species (Chaetocercus, Lophornis) one brood only seems likely for energetic reasons. Generally all species will attempt to nest a second or third time if their initial clutches or broods are lost at an early stage of reproduction.

Conservation status

Since 1987 all members of the Trochilidae have been placed in Appendix II of the Convention on International Trade in Endangered Species (CITES). This means that their conservation status gives sufficient cause for concern that trade in live birds is regulated and is not allowed without a permit. In any case, virtually all countries with populations of trochilids have prohibited the export of live birds so permit applications are rarely granted. Those birds most at risk are listed in Appendix I of the Convention, which forbids any trade in them, but at present the only hummingbird to receive this level of protection is the hook-billed hermit (Glaucis dohrnii).

Although hummingbirds are overwhelmingly breeding birds of the Neotropics, a part of the globe where habitat destruction is widespread and continuing—most particularly in lowland rainforests where the giant trees preferred by loggers are easiest to extract—their situation is not as dramatically bad as that of many other Central and South American bird families. There are various reasons for this. Their nesting sites are generally in the lowest forest strata, and their minute nests can be built in a wide variety of sites. Also, where forest is cleared flowering plants may appear, albeit perhaps briefly, supplying the birds with adequate food, and even crop plantations like banana or coffee are not entirely hostile environments for some species. Additionally, the relative paucity in lowland rainforests of those families of flowering plants preferred by trochilids, compared to montane forest, shrubby habitats, ravines, páramo, and other grasslands, means that these lowland forests, in contrast to the Andes, have never been a stronghold of hummingbird diversity.

The three classes (apart from Extinct) within "globally threatened" in the IUCN Red List Categories are: Critically Endangered—facing an extremely high risk of extinction (a probability of 50% in 10 years) in the wild in the immediate future; Endangered—facing a very high risk of extinction (a probability of 20% in 20 years) in the near future; and Vulnerable—facing a high risk of extinction (a probability of 10% in 100 years) in the medium-term future. Taxa categorized as Near Threatened are not considered to be conservation dependent though are close to qualifying as Vulnerable. Of the 27 globally threatened hummingbirds, 8 are Critically Endangered, 7 Endangered, and 12 Vulnerable. One of the Critically Endangered hummingbirds, the Bogotá sunangel (Heliangelus zusii), is not recognized here as a good species, and neither is the Táchira emerald (Amazilia distans) (Endangered), which is almost certainly a hybrid between the glittering-throated emerald (Polyerata fimbriata) and the white-chinned sapphire (Hylocharis cyanus). So for our purposes the numbers in these classes fall to seven and six respectively, and the total to 25.

If we look at the situation of several of the Critically Endangered hummingbirds more closely the various factors which, alone or especially in combination, can threaten the existence of a species become apparent.

The hook-billed hermit (Glaucis dohrnii) is now restricted to lowland Atlantic forests in eastern Brazil in the states of Bahia and Espírito Santo. There are estimated to be around 50–250 individuals remaining in highly fragmented and scattered remnants of the original habitat covering an area of perhaps less than 39 mi² (100 km²); its original range may once have been as large as 13,514 mi² (35,000 km²). It is the only trochilid in CITES Appendix I. This part of Brazil is densely populated and the influx of people continues unabated, so roads, settlements, and agriculture in the form of coffee, banana, and rubber plantations is eating into the forest. Other threats are logging and mining. Illegal squatters, deliberately started or poorly controlled fires, and road construction continue to degrade protected areas, including even national parks. However, the true status of the bird remains somewhat unclear, and additional hope for its future can be gained from the fact that five new bird species have been found in the wider region in the last ten years while others thought extinct have been rediscovered. Further exploration could conceivably reveal further populations of this hummingbird.

The sapphire-bellied hummingbird (Lepidopyga lilliae) is found only in and around small areas of mangrove forest on the north Colombian coast; all breeding individuals are apparently in a single population which could be less than 50 birds. Huge tracts of this rare habitat have been destroyed by urbanization and pollution which continue to threaten the remaining fragments. A new road and pipeline across the Isla de Salamanca National Park have altered tidal and river flows, leading to increased water salinity levels and extermination of large areas of mangrove. This species is severely threatened by a fatal combination of elements: a very small and probably declining population, a restricted habitat, and damaging human impact. Apart from the National Park 51,892 acres (21,000 ha) the hummingbird is protected within the Ciénaga Grande de Santa Marta Sanctuary 56,834 acres (23,000 ha), but mangrove there has also suffered damage.

The Juan Fernández firecrown (Sephanoides fernandensis) faces an even more complex series of threats. The species is restricted to the Juan Fernández archipelago in the Pacific, 423–493 mi (680–800 km) west of Chile, an important center of biodiversity; 98 of the 142 flowering plants recorded there are endemics. The nominate race is present on the 36 mi² (93 km²) Isla Robinson Crusoe (Más á Tierra), where there are thought to be around 250–400 individuals; it is estimated that the population of the archipelago in the nineteenth century could have been as high as 20,000. The main conservation problems are posed by introduced species, both plants and animals. Only about 10% of the area of Robinson Crusoe retains its native vegetation of evergreen trees, tree ferns, ferns, etc. The Juan Fernández firecrown also faces competition from a recently arrived congener, the green-backed firecrown (S. sephaniodes), which copes much better with the non-native vegetation since they are both of recent mainland origin. There are now estimated to be around 5,000 green-backed firecrowns on Robinson Crusoe. One of the principal threats from an introduced plant is posed by the bramble Rubus ulmifolius; apparently only the smaller female S. fernandensis and both S. sephaniodes sexes feed on its flowers. The islands have been a national park since 1935, a Biosphere Reserve since 1977, and have been nominated for World Heritage Site status. A $2.5 million restoration program by the Chilean government is at present under way; the survival of the Juan Fernández firecrown depends on its success.

The black-breasted puffleg (Eriocnemis nigrivestis) is found only in stunted elfin forest with páramo on mountain crests in northwest Ecuador at altitudes of around 8,200–14,750 ft (2,500–4,500 m). Today it is possibly confined to a single peak, the volcano Pichincha, where three birds were seen in 1993, the first for 13 years. Its numbers in the past can be judged by the fact that over 100 skins can be found in museums. This puffleg is thought to be close to extinction, perhaps with a single population of below 50, because of habitat destruction for cattle grazing, potato growing, and charcoal making. However a concerted effort is being made by local and international conservationists to have its range protected. Eriocnemis nigrivestis occurs during the main part of the flowering season, in the rains between November and February, at elevations of 10,200–14,750 ft (3,100–4,500 m), when it most likely breeds in the humid elfin forest and páramo, spending the rest of the year in temperate forest around 7,875 ft (2,400 m). This critically endangered hummingbird has one advantage in that it is apparently more of a generalist feeder than some others, and although its movements are particularly dependent on the flowering of Fuchsia and Ericaceae it seems that it will accept a wider range of food plants than was once thought.

A crucial aspect of the threat facing the black-breasted puffleg is that it is an altitudinal migrant. This illustrates the important principle that it profits a montane species little to declare part of its range a reserve while another habitat, upor downslope of the protected area and equally important for its survival, continues to be destroyed. For such birds a small, protected area covering a large altitudinal range can be far more valuable than an extensive one spread over a single altitude. Ideally, similar considerations should also apply to long-distance migratory species to safeguard a food supply along the flyway between breeding and winter quarters.

If we briefly examine the reasons for placing some of the remaining 18 species in the IUCN categories Endangered and Vulnerable, the same overall pattern of threats emerges. All six of the species classed as Endangered occur in forest that is being cleared for cultivation, timber, or settlements. Three of them are Mexican endemics, the short-crested coquette (Lophornis brachylophus), Oaxaca hummingbird (E. cyanophrys), and white-tailed hummingbird (Eupherusa poliocerca), and all inhabit the deciduous, semi-deciduous, and montane evergreen forests and forest edges of the Sierra Madre del Sur in the states of Guerrero and Oaxaca. This area is undergoing rapid deforestation. The low-altitude zones are felled to make way for the cultivation of citrus fruits, maize, and coffee. The cloud forest is cleared for coffee plantations, while the oak, fir, and pine trees above 5,900 ft (1,800 m) are cut for timber. Apparently only the white-tailed hummingbird enjoys any degree of protection since some of its range lies within Omiltemi State Ecological Park.

Another pair of endangered and sympatric (in western Ecuador) congeners are little woodstar (Chaetocercus bombus) and Esmeraldas woodstar (C. berlepschi). They are found in one of the most threatened forest types in the Neotropics, moist evergreen forest; C. bombus has a much greater range than C. berlepschi, extending into Peru, but there are few modern records of either species. The remaining hummingbird in this category, the chestnut-bellied hummingbird (A. castaneiventris) from the eastern Andes of Colombia, is threatened as much by its small numbers as by habitat destruction. Rapid and extensive deforestation is widespread throughout the area, even inside sanctuaries, compounded by the apparent rarity of the species; there has been one record of A. castaneiventris in the last 30 years.

The threats faced by the 12 Vulnerable species vary little from the preceding cases. Forest habitat destruction poses the greatest risk to the survival of the majority of them. Others are threatened by critically small populations and/or restricted ranges, usually as a result of past human interference.

Only two of the 25 globally threatened hummingbirds— the purple-backed sunbeam (scrub) and Chilean woodstar (scrub, desert, and agricultural areas)—do not at least partly inhabit forest or woodland of one type or another. Many trochilids specializing in páramo grasslands, arid areas, scrubby thickets, and so on face threats from habitat destruction for cattle raising or other forms of cultivation, but they are possibly more adaptable, taking to secondary growth, plantations, and gardens more readily than true forest species. The few hummingbirds inhabiting high-altitude Andean páramo or puna and bordering stunted forest types, such as the hillstars (Oreotrochilus), the metaltails (Metallura), or the thornbills (Chalcostigma), face a lower risk because these rather inhospitable regions are in the main subject to little human interference. But, of course, the primary factor here is that montane humid tropical and subtropical forest, the home of the majority of trochilids, continues to be destroyed at a completely unsustainable rate.

Brace's emerald (Chlorostilbon bracei) from New Providence Island in the Bahamas is the only hummingbird species definitely known to be extinct. Although the taxon is known only from a single male specimen taken in July 1877, it has been shown to be a good species and not, as thought by many earlier this century, a possible race of the Cuban emerald (C. ricordii), also present on the islands though not on New Providence. Even when the holotype was taken the species must have been rare, and was probably restricted to scrubby thickets around the town of Nassau. No individual was ever seen again, but whether the cause of its extinction was primarily human interference or climate change remains obscure. Fossil remains appear to indicate that one further hummingbird no longer extant once inhabited New Providence Island.

The Bogotá sunangel has been described from a single specimen bought in Bogotá in 1909, though properly examined only in the late 1940s, and is thought to have come from the eastern or central Andes of Colombia, a region where much of the forest has been cleared for crops like potatoes, coffee, and maize. It may still exist in the cloud forest at around 4,600–7,200 ft (1,400–2,200 m) and would presumably be a relict species with a very restricted range. However, there is also the possibility that it could be a hybrid, just as many of the Bogotá trade skins have proved to be. On the basis of this uncertainty the form is not treated here as a good species, although the case for its being so has been well made. If it is a species and has disappeared it would be the first extinction of a trochilid in South America. Where the Colombian forests remain pristine there are still good hummingbird populations, showing that deforestation rather than nineteenth century collecting is responsible for the drastic reduction in range and numbers of many species

Now that killing for plumage is firmly in the past, hummingbirds face no special threats directed at or affecting them in particular. They are difficult birds to keep and only relatively few specialists are interested in them for the aviary trade. But their fate is tied to that of millions of other animal and plant species in the Neotropics if rampant deforestation is allowed to continue at its current rate. The world will be a poorer place if the tragic list of extinctions were to include more hummingbirds.

Significance to humans

Man's attitude to hummingbirds is a very unusual one in his relations with the rest of the animal kingdom: it is wholly characterized by positive emotions, such as aesthetic admiration, affection, and general amazement. As far as is known, hummingbirds have nowhere given cause for the kinds of persecution suffered by other bird families; they are not crop pests, they do not compete with or harm domestic animals, they are not noisy, and there is not much eating on them (although, surprisingly, there is a south Brazilian dish called passarinhos com polenta with hummingbird as the chief ingredient). Apart from adding to the sum of human pleasure they also carry out the important service of pollinating many of their food plants, some of which have coevolved with the birds; at least 58 plant families are pollinated by trochilids in Brazil alone, chief among them the Bromeliaceae.

The persecution to which they have been subjected is rooted in their virtues. Since the earliest times they have been killed for their wonderful plumage, and more recently captured in huge numbers so that people can appreciate them even more at close quarters. Mankind has always been astonished by their unearthly iridescent colors, their acrobatic flying skills, and their small size. They are among the most mysterious creatures on our planet.

Human's feelings towards these birds are well expressed in the names given to them. Their English names parallel both those in other languages and the normally unpoetic scientific nomenclature in attempting to capture some of the hummingbird magic: sapphire, emerald, goldenthroat, mountaingem, jewelfront, brilliant, hillstar, sunbeam, starfrontlet, sunangel, woodstar, sungem, sylph, woodnymph, and fairy. The Spanish name is picaflor (peck the flower), the Portuguese beija flor (kiss the flower).

Native peoples throughout South America use hummingbird plumage in their adornment, and it can be assumed that they always have. The esteem in which these minute glittering feathers were, and are, held is exemplified by the fact that the great ceremonial headdress of the Aztec king Moctezuma (Montezuma) II, the main element of which is the long green uppertail-coverts of the resplendent quetzal (Pharomachrus mocinno), the sacred bird of the Maya and Aztecs, also contains many hundreds of trochilid feathers, interspersed with tiny platelets of gold. The Aztecs kept hummingbirds and other species in special extensive zoos in order to have a supply of feathers and pelts for ceremonial purposes. In 1519 King Moctezuma presented this royal symbol to his eventual conqueror, Hernán Cortés, who in turn gave it to Emperor Charles V as part of a fabulous Aztec treasure of gold, silver, jade, pearl, and turquoise. After seeing this hoard in Brussels, the German artist Albrecht Dürer wrote "I have never seen anything in my entire life that filled my heart with greater delight." The treasure can be seen today in the Museum für Völkerkunde in Vienna.

Huitzilopochtli, hummingbird of the south, from "huitzilin" (hummingbird) and "pochtli" (southern), was actually one of the most powerful of the Aztec gods, associated with battle and human sacrifice, the bird being depicted actually feeding on the blood of sacrificial victims. Fallen warriors were metamorphosed into hummingbirds to accompany the sun on its daily journey for four years before returning to earth to feed on nectar for eternity. Huitzilopochtli had another special place in Aztec mythology as the bird which guided the people on their long trek southwards in search of a new homeland to the spot in present-day Mexico City where they built their capital Tenochtitlan.

The greatest of the gods, the feathered serpent Quetzalcoatl, wore a cape of trochilid feathers and a head adornment of flowers with hovering, feeding hummingbirds. The first ruler of the unified Aztec kingdom was called Huitzilihuite, or hummingbird feather, and during his reign in 1391–1415 he elevated Huitzilopochtli to the position of Sun God, the supreme power in the pantheon, a further member of which was the goddess of earthly pleasures, beauty, and birth Xochi-quetzal, or flower bird, and she too was symbolized by a hummingbird. Hummingbird feathers were an integral part of a bride's wedding dress in Mexico into modern times. The bird was also an integral part of the Aztec calendar. This is more important than it might appear because this highly complex system lay at the very heart of Aztec culture and cosmology. Representations of hummingbirds in stone can be seen throughout the Aztec archaeological sites. The hummingbird is present too in the mythology and artifacts of the South American peoples, particularly the Inca and Nazca of the Andes, but to a much lesser degree than in Mesoamerica. Some of the gigantic figures inscribed by the Nazca on the surface of the dry plateaus of Peru probably represent hummingbirds.

A multitude of stories has arisen from the fact that hummingbirds often appear with the rains, since the flowers bloom then, but of course they are credited in many legends, particularly in the dry southwest of the United States, with being rain bringers. Water vessels are commonly decorated with their image. The Hopi and Zuni peoples incorporate the hummingbird in their rain dances, and their inlaid jewellery of turquoise and silver features the birds as favourite motifs. In a Navajo legend, the first hummingbird was large, white, and very greedy, so much so that it killed many flowers in its search for ever more food. The Creator was displeased and made the bird smaller and smaller to reduce its appetite, but in the process it also lost its song, whereupon the other birds in their pity asked the Creator to compensate the hummingbird with the most beautiful plumage of all, which he duly did.

A belief in the special position of hummingbirds survives today in the form of superstition and folk medicine. On the whole they, and also their nests, are regarded as bringers of good luck. In Costa Rica, dried and perfumed nests are hung around the neck, on belts, or nowadays in cars as lucky talismans. In Mexico, amulets containing mummified or powdered hummingbirds can be bought in markets to bring good luck or success in love. The life-long fidelity of an unwitting partner can be secured by boiling up a dried hummingbird, including feathers, in a soup or stew, or by sprinkling the ashes of a hummingbird heart on the head of the object of desire; similar effects can be achieved by presenting him or her with soap containing trochilid extracts. Evil spirits can be pacified by constructing a little altar with candles before the body of a hummingbird wrapped in red twine.

It was not long before the breathtaking beauty of hummingbird plumage became a very desirable article on the European and North American fashion market. In the second half of the nineteenth century millions of hummingbird skins were exported from Central and South America, not only to decorate ladies' hats and clothes but also for the manufacture of feather pictures, ornaments, and artificial flowers. The collection of mounted specimens was promoted by the naturalist Adolphe Boucard as an interesting and appropriate hobby for ladies. In London in 1888, 12,000 trochilid skins were sold in one month; at one sale there 37,603 hummingbird skins from South America and Trinidad were auctioned; a single delivery from a Brazilian port contained 3,000 skins of the ruby-topaz hummingbird (Chrysolampis mosquitus); 152,000 hummingbirds were sold by one auction house in London between 1904 and 1911, and in 1905, 8,000 were used to make a single shawl. Already in 1851 E. J. Silva Maia of the National Museum in Rio de Janeiro was warning that some species had disappeared in the area purely as a result of trapping for the fashion industry. Some species were probably hunted to extinction in this slaughter since a few were first described from such skins but never subsequently seen, although the hybridization between species, and even genera, frequently reported for trochilids is perhaps responsible for some of these forms.

Confronted with the task of describing hunmmingbirds, the ornithologist's first impulse on lifting the pen is often of a literary nature, if not always of the highest quality. Comte de Buffon, the great eighteenth century naturalist, thought them "of all animated beings … the most elegant in form and brilliant in color. The stones and metals polished by art are not comparable to this gem of nature. She has placed it in the order of birds, but among the tiniest of the race … she has loaded it with all the gifts of which she has only given other birds a share." A generation later John James Audubon described the hummingbird as a "glittering fragment of the rainbow … a lovely little creature moving on humming winglets through the air, suspended as if by magic in it, flitting from one flower to another, with motions as graceful as they are light and airy, pursuing its course and yielding new delights whenever it is seen."

Species accounts

List of Species

Saw-billed hermit

Ramphodon naevius

subfamily

Phaethornithinae

taxonomy

Trochilus naevius Dumont, 1818, Mount Corcovado, Rio de Janeiro, Brazil. Monotypic.

other common names

French: Colibri tacheté; German: Sägeschnabel-Schattenkolibri; Spanish: Ermitaño Picosierra.

physical characteristics

5.5–6.3 in (14–16 cm); female and male 0.19–0.3 oz (5.3–8.5g). A large hummingbird and the only hermit with saw-like serration of the mandibles, and in the adult male, a hooked tip to the upper mandible. Bill straight. Male larger than female. Both sexes alike. Underneath rufous-ochraceous throat with dark gular stripe. Above copperish green. Immatures similar to adults, but upperparts with pale fringes.

distribution

Southeast Brazil (southern Minas Gerais and Espírito Santo to Santa Catarina, records from Rio Grande do Sul).

habitat

Understory of tropical rainforest up to 1,640 ft (500 m).

behavior

Traplining plant visitor. Aggressively defends feeding routes over conspecifics and other hummingbirds. Males establish leks to attract females. Loud metallic flight call.

feeding ecology and diet

Collects nectar from long tubular-shaped flowers at forest understorey. Small arthropods are gleaned from vegetation.

reproductive biology

Breeds from July to September. Cone shaped nest is loosely constructed and attached underneath a tip of a pendent leaf. Two elliptical eggs; incubation 16–17 days by female.

conservation status

Restricted range species, considered Near Threatened. Locally common, but habitat destruction may be a threat in the future.

significance to humans

None known.

White-tipped sicklebill

Eutoxeres aquila

subfamily

Phaethornithinae

taxonomy

Trochilus aquila Bourcier, 1847, Bogotá, Colombia. Three subspecies are recognized.

other common names

English: White/bronze/brown/-tailed sicklebill, common sick-lebill; French: Bec-en-faucille aigle; German: Weisskehl-Sichelschnabel; Spanish: Picohoz Coliverde.

physical characteristics

4.7–5.5 in (12–14 cm); female 0.3–0.35 oz (8–10 g), male 0.35–0.44 oz (10–12.5 g). Unmistakable hummingbird with strongly decurved bill. Underparts black and white streaked, upperparts dark green. Rectrices green and brown with contrasting white tips. Sexes are alike. Immatures resemble adults. Subspecies are alike.

distribution

E. a. salvini: Costa Rica to west Colombia; E. a. heterura: western Andes from southwestern Colombia to west Ecuador; E. a. aquila: east Andes from Colombia to northern Peru.

habitat

Understory of tropical rainforest, older second growth, forest edge near rivers. Often associated with Heliconia patches. Occurs from sea-level to 2,300 ft (700 m), but has also been observed at altitudes up to 6,900 ft (2,100 m) in Costa Rica and in Colombia.

behavior

Sicklebills, unlike most other hummingbirds, perch while feeding on flowers. They establish feeding territories at Heliconia patches, but may also trapline for nectar along regular routes. Loud and melodious "wren-like" song. Sedentary.

feeding ecology and diet

Feeds mainly on Heliconia and Centropogon flowers with tubular corollas similar in curved shape to the bird's bill. Arthropods are caught in the air by hawking.

reproductive biology

Establish leks during the reproductive period. Breeding takes place from January to June in Central America and from June to September in South America. Nest is a loosely woven cup of rootlets and plant fibers attached by cobweb underneath a long, hanging leaf. Two eggs, incubation 16–17 days by female. Chick is black with gray dorsal down; fledging 22–25 days.

conservation status

Common throughout most of its range. Local densities of three to four pairs per km².

significance to humans

None known.

Hairy hermit

Glaucis hirsuta

subfamily

Phaethornithinae

taxonomy

Trochilus hirsutus J. F. Gmelin, 1788, northeastern Brazil. Two subspecies are recognized.

other common names

English: Rufous-breasted hermit; French: Ermite hirsute; German: Rotschwanz-Schattenkolibri; Spanish: Ermitaño Hirsuto.

physical characteristics

4–4.7 in (10–12 cm); female 0.19–0.26 oz (5.5–7.5 g), male 0.21–0.28 oz (6–8 g). A medium-sized hermit with green upperparts, brownish rufous underparts, slightly decurved bill. Four outer tail feathers rufous with broad black subterminal bands and contrasting white tips. Female has paler throat and upper breast; shorter wings and rectrices. Bill more decurved. Immatures similar to adults with upperparts ochraceous.

distribution

G. h. insularum: Grenada, Trinidad, and Tobago; G. h. hirsuta: Panama, Colombia south to Bolivia, Venezuela to Guianas and almost all of Brazil.

habitat

Understory of various forest types and dense secondary growth, woodland clearings, riverine habitats, swamps, bamboo thickets, cerrado, and plantations. Mostly below 3,300 ft (1,000 m).

behavior

Traplining species. Collects spiders from webs.

feeding ecology and diet

Nectar of various understory plants such as Heliconia, Costus, Passiflora, Pachysstachys, Centropogon, and Trichantera species and small arthropods.

reproductive biology

Males establish leks during reproduction. Breeds from January to July on Trinidad, April to July in Panama, September to May in Brazil. Nest records in September in southeast Colombia, December and May in north Colombia, June in eastern Colombia, September to December in Surinam, February, March, July, August and December in French Guiana. Nest is a cone-shaped cup, loosely constructed of plant fibers, built underneath pendent leaf. Eggs visible from the outside. Males sometimes visit nest area and defend nest. Normally two eggs, higher clutch sizes are due to conspecific females laying in the same nest. Incubation 17–19 days by female. Chick is black with gray dorsal down. Fledging 20–25 days. Young remain with female for three to four weeks.

conservation status

Common throughout its extensive range.

significance to humans

None known.

Band-tailed barbthroat

Threnetes ruckeri

subfamily

Phaethornithinae

taxonomy

Trochilus ruckeri Bourcier, 1847, Esmeraldas, Ecuador. Three subspecies currently recognized.

other common names

English: Rucker's hermit; French: Ermite de Rucker; German: Weissbinden-Schattenkolibri; Spanish: Ermitão Barbudo Colibandeado.

physical characteristics

4–4.3 in (10–11 cm); female 0.18–0.25 oz (5–7 g), male 0.19–0.25 oz (5.5–7 g). Medium-sized hummingbird with contrasting underpart coloration, almost straight bill, dark rectrices with white tips. Prominent white base to outer tail feathers, creating a subterminal black band. Immatures have ochraceous

feather fringes on upperparts and light tips to remiges, otherwise similar to adults.

distribution

T. r. ventosus: eastern Guatemala and Belize to Panama; T. r. ruckeri: northern and western Colombia, Ecuador; T. r. venezuelensis: northwestern Venezuela.

habitat

Understory of primary and disturbed forest, secondary growth, forest edge, plantations, and riverine vegetation from sea-level to 4,000 ft (1,200 m).

behavior

Traplining-species. Soft flight call. Song, a series of whistles, can be heard from perching males throughout the day.

feeding ecology and diet

Nectar of Heliconia, Costus, and other tubular flowers; also small arthropods, especially spiders taken from webs or underneath leaves. Nectar robbery recorded by piercing corolla base of tubular flowers too long for its bill.

reproductive biology

Males establish leks during reproduction. Breeds on the Caribbean slope of Costa Rica from February to May, on the Pacific slope from June to September; two nesting seasons in Colombia (January to April and in September). Nest is a loosely built cup of rootlets, plant fibers, vegetable hairs and spider web, similar, but more compact than that of Glaucis, and fixed to the underside tip of a long, pendent leaf. Two eggs; incubation 15–18 days by female. Fledging 23–25 days. Young remain with female for three to four weeks. Male observed in the vicinity of an incubating female.

conservation status

Common throughout its range.

significance to humans

None known.

Green hermit

Phaethornis guy

subfamily

Phaethornithinae

taxonomy

Trochilus guy Lesson, 1832, Trinidad. Four subspecies are recognized.

other common names

English: Guy's hermit; French: Ermite vert; German: Grüner Schattenkolibri; Spanish: Ermitaño Verde.

physical characteristics

5.1 in (13 cm); female 0.14–0.23 oz (4–6.5 g), male 0.14–0.25 oz (4–7 g). A medium-sized hermit with curved bill and an orange gular stripe. Male has nib-shaped central tail feathers, female has shorter and more decurved bill, shorter wings. Lighter underparts, ochraceous belly coloration, and longer rectrices. Immatures like adult female, but have ochraceous uppertail-coverts.

distribution

P. g. coruscus: Costa Rica to northwest Colombia; P. g. emiliae: Colombia (major river valleys); P. g. apicalis: eastern Andean

slopes from north Colombia and northwestern Venezuela to southeast Peru; P. g. guy: Trinidad and northeast Venezuela.

habitat

Understory of humid forest and adjacent forest edges, secondary growth, and plantations with dense vegetation. Recorded between 1,975 and 7,550 ft (600 and 2,300 m).

behavior

Song consists of a series of squeaking notes, presented while perching at the lek. Sharp metallic flight call.

feeding ecology and diet

Nectar of Heliconia, Costus, Razisea, Columnea, Pachystachys, Centropogon, and of introduced plants like Musa and Canna; small arthropods. Casually searching for flowers in Polylepis forests. Traplining.

reproductive biology

Males establish traditional leks throughout the year. Breeds in November to July, in particular January to April in Trinidad; February to September, December in Costa Rica and Panama; June to August in Colombia; July to November in Peru. Nest cone shaped, consisting of moss and fine plant material; placed at the tip of a long leaf, often near or above streams. Males sometimes defend nest, but do not participate in parental care. Two eggs; incubation 17–18 days by female with head towards the leaf. Fledging period 21–23, sometimes 27 days. Chicks have dark skin and sparse dorsal down. Well feathered when about two weeks old.

conservation status

Uncommon to fairly common in most areas.

significance to humans

None known.

Green-fronted lancebill

Doryfera ludovicae

subfamily

Trochilinae

taxonomy

Trochilus ludovicae Bourcier and Mulsant, 1847, Buena Vista, east Andes above Villavicencio, Meta, Colombia. Two subspecies are recognized.

other common names

French: Porte-lance de Louise; German: Grünstirn-Lanzettschnabel; Spanish: Colibri Picolanza Mayor.

physical characteristics

4.3–5.1 in (11–13 cm); female 0.19–0.21 oz (5.5–6.0 g), male 0.2–0.23 oz (5.9–6.4 g). Bill long, slightly upturned. Male with frontlet glittering green, crown and nape dark coppery-bronze, shading to bronzy-green on back; uppertail-coverts blue; tail black, narrowly tipped with dull grey; underparts dull, dark greenish bronze, darker and greener on throat. Female similar to male but frontlet smaller or absent. Immatures similar to adults.

distribution

D. l. veraguensis: north central Costa Rica to western Panama;D. l. ludovicae: extreme eastern Panama (Cerro Tacarcuna), Colombia and western Venezuela, south through Andes to northwestern Bolivia (east slope only from central Ecuador southwards).

habitat

Mid-strata and lower canopy of cloudforest and humid lower montane forest. Males often found along ridges while female prefers ravines and gorges particularly for nesting. Sometimes down at shrub-height. Mainly 2,450–7,550 ft (750–2,300 m).

behavior

Territorial species, defending stands of flowers against other hummingbirds and conspecifics. High pitched melodious song.

feeding ecology and diet

Visits epiphytes with long, tubular, usually pendent corollas, including Ericaceae (Psammisia, Cavendishia, Macleania), Loranthaceae (Psittacanthus), Rubiaceae, and Gesneriaceae. Frequently flycatches, sallying from perch in canopy or along stream, or hover-hawks low over stream; also hover-gleans arthropods from vegetation.

reproductive biology

Breeds in Costa Rica in the latter half of wet season to start of dry (August to January); in Colombia nesting recorded between July and late January. Nest a bulky cup of moss, treefern scales, fine fibers and cobwebs in dark, usually humid site; attached to hanging rootlet or vine rock overhang in ravine or gorge. Two eggs; incubation 19 days; fledging period 25 days.

conservation status

Generally uncommon to locally fairly common in suitable habitat throughout range.

significance to humans

None known.

Rufous sabrewing

Campylopterus rufus

subfamily

Trochilinae

taxonomy

Campylopterus rufus Lesson, 1840, no locality = Guatemala. Monotypic

other common names

French: Campyloptére roux; German: Buntschwanz-Degenflügel; Spanish: Colibri Rojizo Mexicano.

physical characteristics

4.9–5.5 in (12.5–14 cm); female 0.23–0.24 oz (6.6–6.9 g), male 0.32 oz (9 g). Male has medium-sized, slightly decurved black bill; upperparts metallic bronzy-green, postocular spot white; below uniform cinnamon; tail slightly rounded, central pair of rectrices golden-bronze, rest light cinnamon with black subterminal band, edged cinnamon, outermost tail feather cinnamon with lighter edges. Female similar to male, but smaller. Immatures like adults, but with head feathers fringed buffy.

distribution

Pacific slope of Mexico, southern Guatemala and El Salvador.

habitat

Rainforest and forest edge, canyons with pine-oak forests, plantations; occurs at 2,950–6,600 ft (900–2,000 m), occasionally at sea-level, most numerous above 3,300 ft (1,000 m).

behavior

Behavior mostly unknown.

feeding ecology and diet

Nectar of flowering Plantago, Erythrina, Salvia, and Castilleja. Insects are caught in the air by hawking. Male occupies feeding territory at nectar-rich sources.

reproductive biology

Males form small leks during reproduction. Breeds from April to May in Oaxaca, Mexico. Cup-shaped nest of moss lined with whitish thistle down, externally decorated with lichen, rather exposed on horizontal branch, 3.3–6.6 ft (1–2 m) above the ground. Two eggs; incubation 15–16 days by female. Chicks are blackish with two rows of buffy dorsal down; fledging 23–26 days.

conservation status

Restricted-range species. Locally common. Readily accepts human-made habitats such as plantations or pastures with scattered shrubs.

significance to humans

None known.

White-necked jacobin

Florisuga mellivora

subfamily

Trochilinae

taxonomy

Trochilus mellivorus Linnaeus, 1758, India; error=Surinam. Two subspecies recognized.

other common names

English: White-bellied hummingbird; French: Colibri jacobin; German: Weissnackenkolibri; Spanish: Colibrí Nuquiblanco.

physical characteristics

4.3–4.7 in (11–12 cm); female 0.23 oz (6.5 g), male 0.26 oz (7.4g). Bill and feet black. Adult male with head and chest blue, broad white crescent on nape, rest of upperparts bright green including elongated uppertail-coverts; belly and most of tail

white, narrowly edged and tipped black. Plumage of adult female notoriously variable, apparently individually; half to twothirds show the typical female plumage with blue-green breast heavily scaled with whitish, belly dull white, upperparts entirely green and tail mostly green with dark blue tip, outer rectrix with white outer edge and tip; the remainder have plumage more or less male-like with a few only distinguishable from adult male by their longer bills and shorter wings and tails.

distribution

F. m. mellivora: southern Mexico to Panama and Colombia, south to west Ecuador, southeast Peru and northern Bolivia, and east to Venezuela, Trinidad, the Guianas and Amazonian Brazil. F. m. flabellifera: Tobago.

habitat

Humid forest canopy and borders, woodlands, plantations, tall second growth, and gallery forest. Usually high in trees, lower at edges and clearings. Occurs from sea-level up to 3,300 ft (1,000 m).

behavior

Territorial. Mostly silent, at times lengthy hard utters. Sometimes 12–15 males gather at flowering trees.

feeding ecology and diet

Feeds high in flowering trees, including Inga, Vochysia, Erythrina, Bauhinia, and Symphonia, epiphytes, shrubs, and Heliconia along edges and in clearings. Hawks for insects for long periods, hovering and darting high above streams and clearings or sallying from tree-top perches.

reproductive biology

Breeds during dry to early wet seasons between January and July in Costa Rica and Panama; between February and May in northwest Colombia, June and November in east Colombia. Nest is a rather shallow soft cup of light-colored plant down and cobweb on flat upper surface of broad leaf of understory palm (Geonoma, Asterogyne), often sheltered from above by another such leaf, 3.3–10 ft (1–3 m) above ground, sometimes near a stream.

conservation status

Uncommon to common. Adapts to human-made habitats such as tree plantations.

significance to humans

None known.

Sparkling violet-ear

Colibri coruscans

subfamily

Trochilinae

taxonomy

Trochilus [Petasophora] coruscans Gould, 1846, South America. Two subspecies recognized.

other common names

English: Gould's violet-ear; French: Colibri anais; German: Grosser Veilcheohrkolibri; Spanish: Colibrí Rutilante.

physical characteristics

5.1–5.5 in (13–14 cm); female 0.24–0.26 oz (6.7–7.5 g), Male 0.27–0.3 oz (7.7–8.5 g). Male has slightly decurved black bill; upperparts metallic bluish green, bluish violet ear plumes elongated and erect; chin bluish violet, rest of under-parts green with blue belly; tail double-lobed, iridescent green with steely blue subterminal band. Female similar to

male. Immatures have no iridescent coloration, feathers fringed buff.

distribution

C. c. germanus: southern Venezuela, eastern Guyana and northern Brazil; C. c. coruscans: northwestern Venezuela and Colombia through Ecuador and Peru to Bolivia and northwestern Argentina; possibly also northern Chile.

habitat

Forest edges, open woodlands, flowering gardens, plantations, sub-páramo and páramo at 5,600–14,750 ft (1,700–4,500 m).

behavior

Territorial. During display the male hovers close to the female in a semicircle and presents the violet ear plumes. A very vocal species with many local dialects.

feeding ecology and diet

Feeds on nectar of numerous flowers like Castilleja, Centropogon, Clusia, Echeveria, Eleanthus, Erythrina, Eucalyptus, Guzmania, Inga, Salvia, and Puya. Insects are caught in the air by hawking. Forages from ground level to canopy.

reproductive biology

Males establish leks and sing throughout the day from treetops. Breeds in Venezuela from July to October. Cup-shaped nest built of various plant materials, decorated outside with lichens, twigs, or moss; placed on horizontal branch or attached to pendent twig in bush or placed in cleft in rocks. Two eggs; incubation 17–18 days by female. Chicks dark with two rows of dorsal down; fledging period 20–22 days.

conservation status

Common to very common in many habitat types. Readily accepts human-made habitats. A typical hummingbird in many major Andean cities.

significance to humans

None known.

Crimson topaz

Topaza pella

subfamily

Trochilinae

taxonomy

Trochilus pella Linneaus 1758 Surinam. Four subspecies recognized.

other common names

English: King hummingbird; French: Colibri topaze; German: Rotnacken-Topaskolibri; Spanish: Colibrí Topacio.

physical characteristics

Female 5.1–5.5 in (13–14 cm), male 8.3–9.1 in (21–23 cm, including bill c. 1.6 in [4 cm] and tail 4.7–5.1 in [12–13 cm]); female c. 0.35 oz (10 g), male 0.35–0.49 oz (10–14 g). A large strikingly colored hummingbird. Male has straight black bill; top and sides of head and neck velvet black; back glittering crimson to purple, golden on uppertail-coverts; throat bright green with a golden sheen, surrounded by a black band, underparts bright red, undertail-coverts bronze; wings brown; central tail feathers bronzy golden-green, outer rectrices chestnut, submedian tail feathers elongated and crossed. Female bill similar to male's;

back dark green; throat green with crimson discs, underparts green with golden green discs, undertail-coverts iridescent green; central tail feathers bronzy, next pair violet, outermost pair chestnut. Immatures like adult female.

distribution

T. p. pyra: southeastern Colombia, eastern Ecuador, and northeastern Peru to northwestern Brazil (Rio Negro) and south Venezuela (Amazonas); T. p. pamprepta: eastern Ecuador (Suno, Rio Napo); T. p. pella: southern Venezuela (east Bolivar) and the Guianas to northern Brazil (Amapá); T. p. microrhyncha: northcentral Brazil, along south bank of lower Amazon in vicinity of Belém.

habitat

Occurs in lowland rainforests up to 1,640 ft (500 m), mainly inland. Frequently found in tree tops of forests around granite outcrops and along gallery forests near river banks and creeks.

behavior

Territorial. Males announce their presence by shrill calls mainly given from tree tops. During display, male circles in slow-motion manner around perched female.

feeding ecology and diet

Mainly seen foraging for nectar in the upper story of flowering forest trees such as Inga and Bombax, but also visits flowers of vines and epiphytes. Occasionally found in much lower vegetation around inselbergs in Surinam where it forages for nectar near the ground at flowering stands of Costus scaber and in clumps of blooming Pitcairnia nuda. Insects are caught in the air, often high above tree tops.

reproductive biology

Breeds from January to April and again in July to November in the Guianas; no nesting data from other areas. Nests found at 10–26 ft (3–8 m) often on vertical branches or in vines above or near water. The cup-shaped nest, consisting of soft grayish or brownish fibers of Bombax seeds and cobweb, is fairly small compared with the size of the bird. Two eggs; incubation time unknown; chicks black with some pale gray dorsal down; fledging period 21 days. Young remain with female for three weeks.

conservation status

Locally common but frequently considered rare due to its secretive habits in the tree tops.

significance to humans

None known.

Ruby topaz

Chrysolampis mosquitus

subfamily

Trochilinae

taxonomy

Trochilus mosquitus Linnaeus, 1758, Surninam. Monotypic.

other common names

English: Ruby-topaz hummingbird; French: Colibri rubistopaze; German: Mosquitokolibri; Spanish: Colibrí Rubí;.

physical characteristics

3.1–3.5 in (8–9 cm); female and male 0.14–0.18 oz (4–5 g). Male has short straight black bill; crown and nape shining ruby red, back dark brown glossed dull olive; throat and breast

metallic golden; rest of underparts brown; rectrices rich chestnut tipped black. Female has copper-green back, below pale gray (on Trinidad and Tobago, some birds have greenish golden stripe from chin to breast); central tail feathers olive-green, the others rufous-chestnut with shining purple-black subterminal band, tipped white. Immature similar to adult female.

distribution

Eastern Panama and western north and central Colombia, east through Venezuela to the Guianas, then south through northeast and central Brazil to east Bolivia; also islands along north coast from Aruba, Curaçao and Bonaire east to Trinidad and Tobago.

habitat

Occurs in savanna-like vegetation from sea-level to shrubby arid hillsides at 5,600 ft (1,700 m); forages from low down to treetops in clearings, open country, parks, gardens, and plantations. Most numerous below 1,640 ft (500 m).

behavior

Migratory. Arrives in the southern Cauca Valley, Colombia, in May and disappears in September; absent or rare on Trinidad and Tobago in August until November; appears in Paraná, Brazil, in October and leaves in April. Within Brazil north-south migration; along the coastal areas of the Guianas, Venezuela, and Colombia presumably an east-west migration with southward tendency towards Cauca and Magdalena Valleys, Colombia.

feeding ecology and diet

Nectar of flowering shrubs, cultivated crops, cacti, small and large trees. Tiny insects are caught in the air by hawking. Male defends feeding territories in flowering shrubs or trees.

reproductive biology

Breeds from December to June on Trinidad and Tobago, Venezuela, Guianas; September to January in Brazil. Tiny cupshaped nest of fine plant fiber and cobweb, outside decorated with lichen and/or pieces of bark; built in fork of small branch, 3.3–13 ft (1–4 m) above ground, occasionally up to 26 ft (8 m). Two eggs; incubation 15–16 days by female. Chicks black with sparse brownish dorsal down; fledging in 19–22 days.

conservation status

Common resident in the lowlands and coastal ranges.

significance to humans

None known.

Frilled coquette

Lophornis magnificus

subfamily

Trochilinae

taxonomy

Trochilus magnificus Viellot, 1817, Brazil. Monotypic.

other common names

French: Coquette magnifique; German: Prachtelfe; Spanish: Coqueta Magnifica.

physical characteristics

2.8–3 in (7.1–7.7 cm); female and male c. 0.11 oz (3 g). Male has short, straight bill, red tipped black; forehead metallic

green, crest rufous, rest of upperparts bronzy-green, white band across rump; throat shining emerald green, fan-shaped tufts white with iridescent green distal band, rufous at base; rest of underparts grayish green; tail squared, central tail feathers bronzy green, remaining rufous with bronzy green tips and edges. Female lacks tufts and crest, upperparts similar to male, throat with rufous discs and some white with dark crescents, below washed grayish green; tail squared, dark bronzy, distally rufous. Immatures similar to adult female.

distribution

Central eastern Brazil (Espírito Santo south to Santa Catarina), and west to Goiás and Mato Grosso.

habitat

Edges of humid forest, second growth, coffee plantations, and cerrado up to 3,300 ft (1,000 m).

behavior

Disperses after reproductive period. Subordinate to other larger hummingbirds. During the display the male hovers in front of the perching female with fanned tufts.

feeding ecology and diet

Feeds on nectar of small flowering plants like Duranta, Inga, introduced Eucalyptus, Lantana, and Psychotria. Hawks for flying insects.

reproductive biology

Breeds from August to March (Espírito Santo, Brazil). Cupshaped, tiny nest built of fine plant material, outside decorated with lichens; sited 6.6–16 ft (2–5 m) above ground, saddled on branches in bushes or small trees. Two eggs; incubation 12–13 days by female; fledging at 20 days.

conservation status

Rare to locally common. Accepts human-made habitats like flowering gardens and plantations.

significance to humans

None known.

Red-billed streamertail

Trochilus polytmus

subfamily

Trochilinae

taxonomy

Trochilus polytmus Linnaeus, 1758, Jamaica. Monotypic.

other common names

English: Jamaican doctor bird; French: Colibri à tête noire; German: Rotschnabel-Jamaikakolibri; Spanish: Colibrí Portacintas Piquirrojo.

physical characteristics

Female c. 4.1 in (10.5 cm), male 8.7–11.8 in (22–30 cm including 0.9 in [2.3 cm] bill, 5.1–6.7 in [13–17 cm] tail); female c.0.16 oz (4.4 g), male c. 0.18 oz (5.2 g). Male has straight bill, coral red, tipped in black; head black, lateral crown feathers and ear-coverts elongated beyond nape; body iridescent emerald green, darker on back; tail black, forked, second outermost tail feather very long (streamers), scalloped and fluted on the inside. Female's bill similar to male's, but duller red, with distal part black; above green; underparts white, lightly spotted on sides of breast and belly; tail centrally green, rest dark blue with contrasting broad white tips, no streamers.

distribution

Jamaica, except in extreme east.

habitat

Occurs from sea-level to elfin forest and found in all man-made habitats; forages mainly throughout mid-strata and at forest edge. Most numerous at c. 3,300 ft (1,000 m); most birds at higher altitudes are not currently breeding.

behavior

Males are extremely territorial at flowering shrubs or trees. Song faint and complex. Individuals disperse to higher altitudes after main breeding season.

feeding ecology and diet

Forages for nectar at native and introduced flowers, including Hohenbergia, Bauhinia, Meriania, Tecoma, Besleria, Psychotria, Erythrina, Eucalyptus, Spathodea, and Calliandra, generally at height of 6.6–13 ft (2–4 m). Feeds on insects in the air, and takes them also from leaves, flowers, branches, or spider webs.

reproductive biology

Breeds all year round, but chiefly from January to mid-May. Cup-shaped nest of fine plant fibers and cobweb, with lichen attached to outer wall, placed on thin twig 3.3–10 ft (1–3 m) above ground. Two eggs; incubation 17–19 days by female. Chicks black with two dorsal rows of pale gray down; fledging period 19–24 days. Young remain with female for three to four weeks; up to three broods per year.

conservation status

Restricted range species. Common resident, particularly in the Blue Mountains.

significance to humans

None known.

Puerto Rican emerald

Chlorostilbon maugaeus

subfamily

Trochilinae

taxonomy

Trochilus maugaeus Audebert and Viellot, 1801, Puerto Rico. Monotypic.

other common names

English: Antillian emerald; French: Émeraude de Porto Rico; German: Puerto-Rico-Smaragdkolibri; Spanish: Esmeralda Portorriqueña.

physical characteristics

Female 3–3.3 in (7.5–8.5 cm), male 3.3–3.7 in (8.5–9.5 cm); female and male 0.12–0.13 oz (3.4–3.8 g). Male has short, straight bill, upper mandible black, lower red, tipped black; forehead and crown metallic green, dark shining green upperparts and uppertail-coverts; throat iridescent bluish green, rest of underparts and undertail-coverts glossy green; tail forked, shining steely blue. Female has bill black; forehead and crown dull dark green; upperparts and uppertail-coverts shining grass green; throat and breast are light gray becoming darker on belly; tail less forked, outer rectrices basally pale white, becoming brown in center and tipped with a large white spot, second outermost rectrices shing greenish white at base changing to steel blue, tipped with white spot, the next innermost two are

green from base to center, rest of feather dull brown, the inner rectrices are shining green. Immatures resemble adult females.

distribution

Puerto Rico, Virgin Islands.

habitat

Coastal mangroves to forested mountain summits. Open forest, woodland and coffee plantations, from sea-level to 2,625 ft (800 m).

behavior

Forages in low to medium strata 3.3–20 ft (1–6 m). Song consists of rapid tic notes given at various speeds ending in a rapid trill with a high-pitched buzz at the end. Sedentary.

feeding ecology and diet

Feeds on nectar of a wide spectrum of flowers, including Hohenbergia, Vriesea, Dilomilis, Epidendrum, Hedychium, Justicia, Ruellia, Clusia, and Erythrina. Trap-liner. Insects are caught in the air and cleaned from leaves and branches of shrubs and trees.

reproductive biology

Breeds from February to May, but irregular nesting all year round. The nest, a compact structure in the form of a small cup, is composed of dry plant fibers, such as tree fern scales, lined with wild cotton and other soft plant material, externally decorated with lichen. It is generally built in either low or medium-sized plants and trees. Two eggs, incubation 14–16 days by female. Chicks darkish gray with two rows of dark down on the upper side; fledging at 20–22 days.

conservation status

Restricted-range species. Generally common throughout Puerto Rico. Readily accepts human-made habitats.

significance to humans

None known.

Rufous-tailed hummingbird

Amazilia tzacatl

subfamily

Trochilinae

taxonomy

Trochilus tzacatl De la Llave, 1833, Mexico. Five subspecies recognized.

other common names

English: Rieffer's hummingbird; French: Ariane à ventre gris; German: Braunschwanzamazilie; Spanish: Amazilia Tzacatl.

physical characteristics

3.1–4.3 in (8–11 cm); female c. 0.18 oz (5.2 g), male 0.19 oz (5.5 g); subspecies A. t. handleyi 0.25 oz (7.0 g). Male has straight, medium-sized bill, fleshy red with dark tip, or upper mandible blackish; upperparts, flanks, and belly golden green to bonze-green; throat glittering golden green, sometimes with a turquoise gleam in certain lights; belly ashy gray to grayish brown; tail rufous, rectrices with bronze-green to copperish margins. Female similar to male, but has grayish subterminal bars on throat feathers and white belly. Immature darker grayish towards belly.

distribution

A. t. tzacatl: central-east, possibly northeast Mexico to central Panama; A. t. handleyi: Isla Escudo de Veraguas (off northwest Panama; A. t. fuscicaudata: north and west Colombia and west Venezuela; A. t. jucunda: southwest Colombia and west Ecuador; A. t. brehmi: Ricaurte, Nariño, Colombia; endemic to the upper Río Guiza valley.

habitat

Edges of humid evergreen forest, clearings, plantations, and man-made habitats. Often in second growth and semi-open,

thicket-rich areas; in South America, partially in gallery forest and mangrove. Occurs from sea-level to 8,200 ft (2,500 m).

behavior

Mainly territorial, also when associated in groups; intruders, even larger trochilids, butterflies, and euglossine bees are sometimes attacked in diving flight. More sedentary in humid regions than in arid areas. Northernmost population winters along Pacific and Caribbean coast of Mexico. Vagrants may occur farther north of the range limit and have been recorded from southern Texas in summer and autumn. Seasonal movements are known from Colombia and Ecuador due to altitudinal variation of flowering periods. Frequently gathers in some numbers with conspecific or congeners such as A. amazilia and A. rutila.

feeding ecology and diet

Nectar and arthropods. Forages in all strata from near the ground to the more open sides of tree crowns. Feeds on a wide range of plants, including Antigonon, Callistrimon, Clitoria, Costus, Isertia, Hamelia, Heliconia, Stachytarpheta, Tabebuia, and Lantana. Gleans insects and small spiders from leaves and branches.

reproductive biology

Breeds all year round. Favorite nest-sites are horizontal branches in smaller trees or shrubs, mostly 6.6–16 ft (2–5 m) above ground; sometimes cup-shaped nest is placed in fork. Nest material varies, and includes plant down, yellowish brown to grayish brown fibers, cobweb, pieces of dead leaves, moss, and lichen. Two eggs; incubation 15–16 days by female. Chicks blackish, with buff dorsal down; fledging at 18–22 days.

conservation status

Common to very common throughout range.

significance to humans

None known.

Velvet-purple coronet

Boissonneaua jardini

subfamily

Trochilinae

taxonomy

Trochilus jardini Bourcier, 1851, Nanegal, Ecuador. Monotypic.

other common names

English: Jardine's hummingbird; French: Colibri de Jardine; German: Hyazinthkolibri; Spanish: Colibrí Sietecolores.

physical characteristics

4.3–4.7 in (11–12 cm); female and male 0.28–0.3 oz (8.0–8.5 g). Bill straight, black. Male shining bluish green above with head and throat velvety black; crown, breast, and belly glittering purplish blue; underwing-coverts cinnamon and conspicuous in flight; tail slightly forked, central feathers black, the rest white with black tips and edges; small leg puffs also white. Female similar but duller in coloration, with feathers of breast and belly fringed buff; wings are shorter and tail less deeply forked than in male. Immatures like females.

distribution

Pacific slope of western Andes in southwest Colombia and northwest Ecuador.

habitat

Prefers wet mossy forests and forest boders in tropical and subtropical zones, but can also be found at shrubby clearings in Pacific lowlands and on lower slopes. Records range from 1,150–7,200 ft (350–2,200 m), commonest above 4,000 ft (1,200 m).

behavior

Defends nectar-rich food sources. Sedentary, but seasonal altitudinal dispersal known in Colombia.

feeding ecology and diet

Usually seen feeding at flowers from lower strata to tree tops. Insects are caught in the air by hawking.

reproductive biology

Breeds from January to March. Nest cup-shaped, made of moss and lichen, placed on a horizontal branch or thin fork. Two eggs; incubation by female.

conservation status

Restricted-range species. Uncommon and very local.

significance to humans

None known.

Sword-billed hummingbird

Ensifera ensifera

subfamily

Trochilinae

taxonomy

Ornismya ensifera Boissonneau, 1840, Bogotá, Colombia. Monotypic.

other common names

French: Colibri porte-épée; German: Schwertschnabelkolibri; Spanish: Colibrí Picoespada.

physical characteristics

6.7–9 in (17–22.8 cm, including bill of 3.5–4.3 in [9–11 cm]); female and male 0.42–0.53 oz (12–15 g). Longest bill of any hummingbird; straight to slightly upturned, black. Male is dark green, head coppery, postocular spot white; throat blackish, underparts glittering emerald green, belly dark gray; tail forked, blackish. Female similar to male, has underparts lighter with throat and belly washed gray with green discs; tail less forked. Immatures resemble adult females.

distribution

Andes from west Venezuela through Colombia, Ecuador, and Peru to northeast Bolivia.

habitat

Humid to semi-humid upper montane forest and forest edges, sometimes at patches of shrubs in páramo, at 5,600–11,500 ft (1,700–3,500 m), commonest at 8,200–9,850 ft (2,500–3,000 m).

behavior

Sedentary. A species little known to science.

feeding ecology and diet

Flowers visited for nectar have long, pendent corollas, and include Fuchsia, Datura, Passiflora mixta, and Tacsonia. Hawks for insects in swift-like manner with wide open bill. Trap-lines for flowers in mid- to upper strata; sometimes perches below flowers while feeding.

reproductive biology

No reliable information. One unconfirmed observation of a female defending a possible nesting site high up in a tree in April (Ecuador); another doubtful description records several moss nests 50 ft (15 m) above ground in a tree.

conservation status

Rare to locally common.

significance to humans

None known.

Anna's hummingbird

Calypte anna

subfamily

Trochilinae

taxonomy

Ornismya anna Lesson, 1829, San Francisco, California. Monotypic.

other common names

French: Colibri d'Anna; German: Annakolibri; Spanish: Colibrí de Ana.

physical characteristics

3.9–4.3 in (10–11 cm); female 0.12–0.17 oz (3.3–4.7 g), male 0.12–0.2 oz (3.3–5.8 g). Male has short, straight black bill; upperparts golden green; head and elongated lateral throat feathers iridescent deep rose red, underparts gray washed with green, undertail-coverts green, edged gray; central rectrices golden green, lateral tail feathers dark greenish bronze. Female similar to male, head grayish, small white postocular spot, lacks iridescent rose red on head and throat, red discs on throat appear with age; median rectrices golden green, rest blackish, outermost feathers tipped white. Immatures similar to adult females.

distribution

Southwest Canada (British Columbia) through west United States (east to south Arizona) to northwest Mexico. Winter range highly unsettled, species occuring irregularly south to north Sonora, southeast to Gulf Coast of United States, and even north to southeastern Alaska; sporadically occurs much further east.

habitat

Chaparral, oak woodland, canyon bottoms, open woodland with evergreen broadleaf trees, riparian woodland, savanna-like vegetation, coastal shrub, and urban and suburban environments, at sea-level to 5,900 ft (1,800 m).

behavior

Forages in low to high strata, usually at 6.6–26 ft (2–8 m). Male occupies feeding territories at nectar-rich sources. Extensive post-breeding wandering. In recent years the species has considerably expanded its range of winter occurence in the United States towards the southeast. Recently recorded for first time in San Luis Potosí (north-central Mexico).

feeding ecology and diet

Nectar of flowering native and introduced perennials, shrubs and trees including Ribes, Diplacus, Salvia, Keckiella, Aquilegia, Mimulus, Tecomaria, Kniphofia, Agave, and Eucalyptus. Insects are caught in the air by hawking or taken from foliage. Small flies constitute almost half of the arthropod consumption.

reproductive biology

Breeding occurs from November to May, occasionally to July. Cup-shaped nest constructed of soft material such as plant down, feathers, and hair, held together by spider web and insect cocoon fibers and sometimes rodent hairs; decorated with lichen, moss, pieces of dead leaves and bark on external wall; placed on horizontal twigs, usually 6.6–20 ft (2–6 m), sometimes up to 65 ft (20 m) above ground. Two eggs; incubation 14–19 days by female. Chicks black with two dorsal rows of dull grayish down; fledging period 18–26 days.

conservation status

Common throughout range and at present apparently in process of expansion.

significance to humans

None known.

Resources

Books

del Hoyo, J., A. Elliot, and J. Sargatal, eds. Handbook of the Birds of the World. Vol. 5, Barn-owls to Hummingbirds. Barcelona: Lynx Editions, 1999.

Dorst, J. South America and Central America, a Natural History. New York: Random House, 1967.

Grant, K. A., and V. Grant. Hummingbirds and Their Flowers. New York: Columbia University Press, 1968.

Greenewalt, C. H.. Hummingbirds. New York: Doubleday, 1960.

Johnsgard, P. A. The Hummingbirds of North America. Washington, DC: Smithsonian Institution Press, 1997.

Martin, A., and A. Musy. La Vie des Colibris. Neuchatel, Switzerland: Ed. Delachaux & Niestlé, 1959.

Price, P. W., T. M. Lewinsohn, G. W. Fernandes, and W. W. Benson. Plant-Animal Interactions. New York: John Wiley & Sons, 1991.

Ruschi, A. Aves do Brasil. Beija-Flores, Vols. 4 and 5. Rio de Janeiro: Expressao e Cultura, 1982.

Schuchmann, K.-L. Kolibris. Frankfurt: Biotropic, 1979.

Sibley, C. G., and J. A. Ahlquist. Phylogeny and Classification of the Birds. New Haven, CT: Yale University Press, 1990.

Sick, H. Birds in Brazil. A Natural History. Princeton, NJ: Princeton University Press, 1993.

Skutch, A. F. The Life of the Hummingbird. London: Octopus Books Ltd., 1974.

Stiles, F. G., and L. L. Wolf. Ecology and Evolution of Lek Mating Behavior in the Long-tailed Hermit Hummingbird. Washington, DC: AOU Ornithological Monographs 27,1979.

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Periodicals

Chai, P., J. S. C. Chen, and R. Dudley. "Transient Hovering Performance of Hummingbirds Under Conditions of Maximal Loading." Journal for Experimental Biology 200 (1997): 921–929.

Cintra, R. "Black-eared Fairy (Heliothrix aurita, Trochilidae) Using a Gliding Flight Like Falling Leaves When Leaving the Nest." Journal f. Ornithologie 131 (1990): 333–335.

Cody, M. L. "Interspecific Territoriality Among Hummingbird Species." Condor 70 (1968): 270–271.

Feinsinger, P., and R. K. Colwell. "Community Organization Among Neotropical Nectar Feeding Birds." American Zoologist 18 (1978): 779–795.

Hainsworth, F. R., and L. L. Wolf. "Crop Volume, Nectar Concentration, and Hummingbird Energetics." Comparative Biochemical Physiology 42A (1972): 359–366.

Hainsworth, F. R., B. G. Collins, and L. L. Wolf. "The Function of Torpor in Hummingbirds." Physiological Zoology 50 (1977): 215–222.

Hixon, M. A., F. L. Carpenter, and D. C. Patton. "Territory Area, Flower Density, and Time Budgeting in Hummingbirds: An Experimental and Theoretical Analysis." American Naturalist 122 (1983): 366–391.

Prinzinger, R., T. Schäfer, and K.-L. Schuchmann. "Energy Metabolism, Respiratory Quotient and Breathing Parameters in Two Convergent Small Bird Species: The Fork-tailed Sunbird (Aethopyga christinae, Nectariniidae) and the Chilean Hummingbird (Sephanoides sephaniodes, Trochilidae)." Journal of Thermal Biology 17 (1992): 71–79.

Pyke, G. H. "Optimal Foraging in Hummingbirds: Rule of Movement Between Inflorescensce." Animal Behaviour 29 (1981): 889–896.

Schuchmann, K.-L. "Reproductive Biology of the Purple-crowned Fairy (Heliothrix barroti, Trochilidae): Notes on Antipredator Behaviour." Journal f. Ornithologie 131 (1990): 335–337.

Sibley, C. G., J. E. Ahlquist, and B. L. Monroe, Jr. "A Classification of the Living Birds of the World, Based on DNA-DNA Hybrization Studies." Auk 105 (1988): 409–423.

Stiles, F.G. "Taste Preferences, Color Preferences and Flower Choice in Hummingbirds." Condor 78 (1976): 10–26.

Karl-L. Schuchmann, PhD, Prof