White-tailed Hawk, one of the most attractive of the Buteo species, is essentially a Texas specialty for United States birders. It is accidental at best in Arizona with an 1897 breeding record considered questionable. Even in adjacent Sonora, Mexico this hawk is rare with no breeding evidence (Munson 1998).
White-tailed Hawks feed on a variety of mammals, birds, reptiles, amphibians, insects and other arthropods. Hunting is usually done from perches and starts as early as an hour after sunrise and may continue as late as sunset. These hawks also search for prey while hovering. Prey items range from birds as large as Northern Bobwhite (Colinus virginianus) to insects captured in the air (Farquhar 1992).
DISTRIBUTION. During the 1987-1992 field work seasons of the TBBA project, atlasers found 21 confirmed, 28 probable and 39 possible breeding sites for White-tailed Hawks south of the 30th parallel, east of the 100th meridian and west of the 95th meridian. Most of these were in the Coastal Sand Plain, Coastal Prairies and South Texas Brush Country regions (see the region map in Lockwood and Freeman ). The highest North American Breeding Bird Survey route averages came from Brazos (1.9), Kleberg (1.2) and Brooks (1.0) counties (Price et al. 1995).
Outside Texas the range of this hawk extends locally through Mexico, Central and South America (east of the Andes) to central Argentina (Howell and Webb 1995, Am. Ornithol. Union 1998).
SEASONAL OCCURRENCE. White-tailed Hawks are resident in their range and breed in Texas from late January to July or even late August, based on egg collection dates of February 1 to August 4 (Oberholser 1974, Lockwood and Freeman 2004).
BREEDING HABITAT. In Texas these hawks breed from near sea level to about 50 m (160 ft) elevation (Oberholser 1974). On the Coastal Sand Plain of south Texas, White-tailed Hawks nest in savannas in short trees and shrubs with average heights of 3.5 m(12 ft) and canopy diameters averaging 5.5 m (18 ft). Crested Caracaras (Caracara cheriway), also nesting in savannas, chose taller trees and shrubs with broader and denser canopies. Red-tailed Hawks (B. jamaicensis) nest in woodlands adjoining these savannas (Actkinson et al. 2007).
The nest is loosely constructed of dried branches, twigs ,grasses and forb stems. The flat, elliptical nest is, about 46.5-54 cm (18.5-21.5 in) in outside dimension and 8 cm (3 in) cup depth. Additional nests may be built and not used. In this cup the female usually lays 2 (range 1-4) dull white, usually unmarked, eggs at 1-2 day intervals. Most incubation is done by the female and takes about 31 days, starting with the laying of the first egg. The young remain in the nest about 7 weeks, then stay with their parents for as long as 7 months or until the next breeding season. Incubating birds usually leave their nest when a human is still far away, either disappearing or soaring high overhead (Harrison 1979, Farquhar 1992).
STATUS. White-tailed Hawks are currently considered uncommon to locally common in Texas (Lockwood and Freeman 2004) and fairly common to uncommon, but local, in Mexico (Howell and Webb 1995). The TBBA map lacks the furthest inland breeding locations shown on the map in Oberholser (1974). Although the breeding range may have decreased since historic times, many of the population and range changes described by Oberholser (1974) and Farquhar (1992) have been at least partly reversed.
Text by Robert C. Tweit (2008)
Actkinson, M. A., W. P. Kuvlesky Jr., C. W. Boal, L. A. Brennan and F. Hernandez. 2007. Nesting habitat relationships of sympatric Crested Caracaras, Red-tailed Hawks and White-tailed Hawks in south Texas. Wilson J. Ornithol. 119: 570-578.
American Ornithologists’ Union. 1998. Checklist of North American birds, 7th ed. Am, Ornithol. Union, Washington, DC.
Farquhar, C. C.. 1992. White-tailed Hawk (Buteo albicaudatus). In The birds of North America, No. 32 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Harrison, H. H. 1979. A field guide to western birds’ nests. Houghton Mifflin, Boston, MA.
Howell, S. N. G. and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, New York.
Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.
Monson, G. 1998. White-tailed Hawk (Buteo albicaudatus). In The raptors of Arizona, pp96-98 (R. L. Glinski, ed.). University of Arizona Press, Tucson.
Oberholser, H. C. 1974. The bird life of Texas, University of Texas Press, Austin.
Price, J., S. Droege, and A. Price. 1995. The summer atlas of North American birds. Academic Press, New York.