White-tailed hawk
The white-tailed hawk is a large bird of prey species found in tropical and subtropical environments of the Americas.
Distribution and habitat
The white-tailed hawk is found from the coastal of Texas and the Rio Grande Valley south to central Argentina. Its range also includes many Caribbean islands in the Lesser Antilles and Trinidad and Tobago. It prefers open or semi-open regions up to 2,000 ft ASL, with few trees to obstruct flight. It is not a migratory bird, though some populations may make regional movements when food is scarce. It commonly perches on bushes, trees, or telephone poles, stands on the ground, or engages in soar. Generally, it prefers arid habitats and rarely occurs in areas with heavy rainfall.Though it may disappear from unsuitable locations following habitat fragmentation, it has a wide range and is not considered to be a globally threatened species by the IUCN.
Description
The white-tailed hawk is a large, stocky hawk. It is similar in size to Swainson's and red-tailed hawks, with mean measurements slightly larger than the former and slightly smaller than the latter. It can attain a total length of and a wingspan of. Body mass has been reported as and . Standard measurements include a wing chord of, a tail of, and a tarsus of.Adult birds are grey above and white below and on the rump, with faint pale grey or rufous barring. The short tail is white with a narrow black band near the end that is conspicuous in flight. A rusty-red shoulder patch is also characteristic when the bird is perched with wings closed. The upperwings are dark, mixed with grey near the bases of the blackish primary remiges. The underwing is whitish, with indistinct brownish barring on the underwing coverts; this barring extends onto the flanks and thighs. The iris is hazel, the cere is pale green, the beak is black with a horn-colored base, and the feet are yellow with black talons.
Immature birds are darker than adults; they may appear nearly black in poor light, particularly those with little white below. The wing lining is conspicuously spotted black-and-white; the rusty shoulder patch is absent in younger birds. The tail changes from brown with several dark bars to greyish with a hazy dark band as the bird approaches maturity. The bare parts are colored similar to the adult.
In the Southern Hemisphere winter, young birds are sometimes mistaken for migrant red-backed hawks.
Call
Its call is a high-pitched cackling ke ke ke..., with a tinkling quality that reminds some of the bleating of a goat or the call of the laughing gull.Subspecies
Three subspecies are known:| Image | Subspecies | Description | Distribution |
| Geranoaetus albicaudatus hypospodius | Intermediate in size and coloration. No dark morph. | coastal Texas and the Rio Grande Valley through Middle America to northern Colombia and western Venezuela. | |
| Geranoaetus albicaudatus colonus | Small and pale. Dark morph is ashy grey all over, except for the tail and underwing coverts; sometimes extensively marked rufous on the underside. Dark-morph immatures are sometimes black all over, except for the tail. | Eastern Colombia to Suriname south to the mouth of the Amazon River, extending into the Caribbean. | |
| Geranoaetus albicaudatus albicaudatus | Large and dark; throat usually black. The dark morph appears blackish above, blackish-brown below. | Southern Amazon rainforest to central Argentina |
Ecology
Feeding
Its preferred hunting technique is to hover and observe the surroundings for signs of potential prey, gliding to another place when nothing is found. The diet of the white-tailed hawk varies with its environment. Rabbits make up the majority of the hawk's diet in southern Texas, while lizards 12 in or more in length are preferred prey in the Dutch West Indies. Other animals such as cotton rats, snakes, frogs, arthropods, and small birds like passerines or quails are also eaten; it may take chickens if no other food source is available. In the open cerrado of Brazil, mixed-species feeding flocks react to white-tailed hawks with almost as much alarm as they do to dedicated bird predators such as the aplomado falcon. In the tropics, white-tailed hawks rank amongst the main predators of the small monkeys known as marmosets.The white-tailed hawk is also known to feed on carrion and to gather with other birds at brushfires to catch small animals fleeing the flames.