White-tailed hawk
| White-tailed hawk | |
|---|---|
| |
| Adult at Salvador Zoo, Ondina, Salvador, Bahia, Brazil | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Accipitriformes |
| Family: | Accipitridae |
| Genus: | Geranoaetus |
| Species: | G. albicaudatus
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| Binomial name | |
| Geranoaetus albicaudatus | |
| Subspecies[3] | |
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| Synonyms | |
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Buteo albicaudatus | |
The white-tailed hawk (Geranoaetus albicaudatus) is a large bird of prey species found in tropical and subtropical environments of the Americas.
Description
[edit]The white-tailed hawk is a large, stocky hawk. It is similar in size to the Swainson's (Buteo swainsoni) and red-tailed hawks (Buteo jamaicensis), with mean measurements slightly larger than the former and slightly smaller than the latter. It can attain a total length of 44–60 cm (17–24 in) and a wingspan of 118–143 cm (46–56 in). Body mass has been reported as 880–1,240 g (1.94–2.73 lb) (B. a. hysopodius) and 865–1,010 g (1.907–2.227 lb) (B. a. colonus). Standard measurements include a wing chord of 39–46.2 cm (15.4–18.2 in), a tail of 19.4–22 cm (7.6–8.7 in), and a tarsus of 8–9.2 cm (3.1–3.6 in).[4] 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.[5]
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.[5]
In the Southern Hemisphere winter, young birds are sometimes mistaken for migrant red-backed hawks (Geranoaetus polyosoma).[5]
Call
[edit]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.[5]
Subspecies
[edit]Three subspecies are known:[5]
| Image | Subspecies | Description | Distribution |
|---|---|---|---|
_Anzalduas_Co_Park_Mission_TX_2018-03-09_09-30-28_(38933936220).jpg) |
Geranoaetus albicaudatus hypospodius | Intermediate in size and coloration. No dark morph. | coastal Texas and the Rio Grande Valley[6] through Middle America to northern Colombia and western Venezuela. |
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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. |
_(8077680716).jpg) |
Geranoaetus albicaudatus albicaudatus | Large and dark; throat usually black (except in western Argentina). The dark morph appears blackish above, blackish-brown below. | Southern Amazon rainforest to central Argentina |
Distribution and ecology
[edit]
The white-tailed hawk is found from the coastal of Texas and the Rio Grande Valley[6] 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 (c. 600 m) 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.[5]
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.[7]
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 (30 cm) or more in length are preferred prey in the Dutch West Indies. Other animals such as cotton rats, snakes, frogs, arthropods (especially grasshoppers, cicadas, and beetles), 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.[8] 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.[9] In the tropics, white-tailed hawks rank amongst the main predators of the small monkeys known as marmosets.[10]
Breeding pairs build nests from freshly broken twigs, often from thorny plants. Nests are typically placed 5–15 ft (1.5–5 m) or more above the ground in a tree or yucca, preferably in an elevated location offering good visibility from the nest. The interior is cushioned with dried grasses and other fine materials; green twigs of mesquite or other aromatic plants are often added, perhaps to deter parasites. Like many Accipitridae, white-tailed hawks tend to reuse nest sites. Nests built up over the years can thus reach sizes of up to 3 ft (1 m) across. The eggs are white, often lightly spotted with brown or lavender; between one and three (usually two) are laid per clutch. When approached at the nest, adults become airborne and observe the intruder from above. This contrasts with related hawks, which typically wait longer before flushing and may launch direct attacks.[5]
Footnotes
[edit]- ^ BirdLife International (2020). "Geranoaetus albicaudatus". IUCN Red List of Threatened Species. 2020: e.T22695906A169001701. doi:10.2305/IUCN.UK.2020-3.RLTS.T22695906A169001701.en. Retrieved 19 November 2021.
- ^ Vieillot, 1816. Buteo albicaudatus (protonym). Nouv. Dict. Hist. Nat., nouv. éd., 4, p. 477. BHL
- ^ Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.2). doi : 10.14344/IOC.ML.10.2.
- ^ Ferguson-Lees, J.; Christie, D. (2001). Raptors of the World. London: Christopher Helm. ISBN 0-7136-8026-1.
- ^ a b c d e f g HCT (2008)
- ^ a b "White-tailed Hawk". The Birds of North America Online. Cornell Laboratory of Ornithology. Retrieved 2009-01-06.
- ^ Faria et al. (2006), BLI (2008)
- ^ Ragusa-Netto (2000)
- ^ eNature (2007), HCT (2008)
- ^ "Callithrix kuhlii (Weid's black-tufted-ear marmoset)".
References
[edit]- eNature (2007): White-tailed Hawk. Retrieved 2008-NOV-19.
- Faria, Christiana M.A.; Rodrigues, Marcos; do Amaral, Frederico Q.; Módena, Érica & Fernandes, Alexandre M. (2006): Aves de um fragmento de Mata Atlântica no alto Rio Doce, Minas Gerais: colonização e extinção [The birds of an Atlantic Forest fragment at upper Rio Doce valley, Minas Gerais, southeastern Brazil: colonization and extinction]. Revista Brasileira de Zoologia 23(4): 1217-1230 [Portuguese with English abstract]. doi:10.1590/S0101-81752006000400032 PDF fulltext
- Hawk Conservancy Trust (HCT) (2008): White-tailed Hawk – Buteo albicaudatus. Version of 2008-NOV-19. Retrieved 2008-NOV-19.
- Ragusa-Netto, J. (2000): Raptors and "campo-cerrado" bird mixed flock led by Cypsnagra hirundinacea (Emberizidae: Thraupinae). Revista Brasileira de Biologia 60(3): 461-467 [English with Portuguese abstract]. doi:10.1590/S0034-71082000000300011 PMID 11188872 PDF fulltext
External links
[edit]
- White-tailed hawk Information eNature.com