Short-tailed Hawk

Taxobox
name = Short-tailed Hawk


image_width = 300px
image_caption = Juvenile black phase
status = LC | status_system = IUCN3.1
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Falconiformes
familia = Accipitridae
genus = "Buteo"
species = "B. brachyurus"
binomial = "Buteo brachyurus"
binomial_authority = Vieillot, 1816

Short-tailed Hawk, "(Buteo brachyurus)", is a bird of prey in the family Accipitridae, which also includes the eagles, hawks and Old World vultures. As a member of the genus "Buteo", it is referred to in British usage as a buzzard rather than a true ("Accipiter") hawk.

Short-tailed Hawk breeds in tropical and subtropical America from southeastern Brazil and northern Argentina north through Central America to northern Mexico. There is also a population in southern Florida, USA. It is generally found below 2000 metres, mostly between 1400 metres and sea level. It is replaced by the closely related White-throated Hawk, previously considered a subspecies of Short-tailed, in the Andes of Colombia and south to central Argentina and Chile. The Short-tailed Hawk is uncommon and local in most of its range. As far as is known it is a year-round resident except that most of the Florida population migrates in winter to the southern tip of the state, including the Keys.

This species is associated with woodland, often near water. The large stick nest is built in a tree, often a bald cypress in Florida. The 1-3 eggs are white, usually with dark spots and blotches.

Short-tailed Hawk is a small buzzard, 40 cm long with a 90 cm wingspan. Males average about 400 grams and females over 500, but the sexes are indistinguishable in the field. It has broad rounded wings, the tips of which are curved upwards while soaring, and a broad tail that despite the bird's name is of average length for a buteo in proportion to the body. Its call is a high-pitched scream similar to other buzzards.

This species occurs in two colour morphs with no intermediates; the dark form predominates in Florida and the light form elsewhere in its range. The adult light morph has dark brown upperparts. The underparts are white, except that the tail and flight feathers are grey barred with dark. The immature is similar to the adult but the face is streaked rather than white, and the tail bands are of equal width, whereas the adult has a broad bar near the tail tip.

The adult dark morph has black-brown upperparts and underparts, apart from the tail and flight feathers, which are grey barred with dark as in the light morph but possibly with darker grey. The young bird has the same tail pattern as the light-morph immature, and the underparts are spotted with white.

This hawk eats mainly birds. In Florida (the only place where much is known about its natural history), its prey ranges in size from wood warblers up to Bobwhites and it most often takes Red-winged Blackbirds and Eastern Meadowlarks. It also eats some rodents, frogs, lizards and large insects. It hunts, often at the borders between wooded and open areas, from soaring flight. A frequent maneuver is to come to a stop, heading into the wind, with its wings held stationary ("kiting"). It typically attacks prey with a nearly vertical swoop, sometimes pausing and then continuing downward in a "stair-step" manner.

Plumage

One of the most interesting things about this bird is the melanistic, or black phase; in fact, this bird is known among the natives of Florida as the "little black hawk".

Most of the North American Buteos have a melanistic phase (e.g., Red-tailed Hawk, "Buteo jamaicensis", Swainson's Hawk, "Buteo swainsoni"), although wholly black plumage is comparatively rare, whereas in the North American population of "Buteo brachyurus" it seems to be the prevalent form.

For a long time, it was thought that the dark phase of the present bird was a distinct species. When the Short-tailed Hawk was first taken in Florida by W. S. Crawford at Oyster Bay, Lee County, January 28, 1881, and recorded by Robert Ridgway in the "Bulletin of the Nuttall Ornithological Club" for October of that year (Vol. VI, pp. 207-214), the question whether or not the black phase ("Buteo "fuliginosus") was specifically identical with the light phase ("B. brachyurus") was not definitively settled.

References

* Database entry includes a lengthy justification of why this species is of least concern
* K. Miller and K. Meyer, "A Closer Look: Short-Tailed Hawk", "Birding", October 2004.
* S. L. Hilty, "Birds of Venezuela", Princeton University Press, 2002