Cathartes aura
Of the seven species of the New World vultures, the Turkey Vulture is the most common and the most widely distributed, ranging from south Canada to southern South America. In winter this efficient scavenger migrates from the northern part of its range, where a carcass will freeze, to the southern part of the United States and south into South America. The Turkey Vulture breeds throughout Texas, but the winter population is largely confined to east of a line running from Wichita Falls (Pulich 1988) south to Del Rio. It might be noted, however, that there are records for this bird in Big Bend National Park for every month of the year except January (Warner 1973). Casual winter lingerers in the west were also noted by Oberholser (1974).
DISTRIBUTION: The Turkey Vulture breeds throughout Texas, adapting to the forests and swamplands of east Texas, the open prairies farther west, and the high, arid lands of the Trans-Pecos. Abundant in the east, and common to fairly common throughout much of the state, the species can be scarce in the northwest and far west quarters of the state. Oberholser observed this pattern as did, more recently, TBBA atlasers. The relative dearth of observations in the western Panhandle and the Trans-Pecos may also be in part a reflection of limited numbers of observers, and because of the paucity of public lands in Texas, lack of access to many areas. Significantly, the heavily visited Big Bend area produced no fewer than six confirmed breeding records. In the nineteenth century Turkey Vultures, and the closely related Black Vultures, were notorious scavengers in city dumps (Sprunt 1955), but today, with modern sanitation, they are almost entirely absent from large metropolitan areas except for occasional migrating birds. They are, for example, listed as rare in a Dallas County checklist (Pulich 1977).
SEASONAL OCCURRENCE: The Turkey Vulture, conspicuous in flight, is secretive in its breeding habits. Nests are not often encountered. Out of 1,549 records obtained by the TBBA, only 79 were confirmed records. Turkey Vultures have a long breeding season. Oberholser records eggs as early as February 15, and as late as July 30. TBBA records suggest that breeding is at its height in April and May, with the earliest TBBA confirmed record for eggs being March 2. At latilong 32095, D1, in east Texas a nest with two eggs, one already pipped, was photographed on April 18, 1990.
BREEDING HABITAT: The Turkey Vulture is highly adaptable in its choice of breeding habitat. No nest is built, although twigs or leaf litter already present may be used. The nest is normally on the ground (Kirk and Mossman 1998). In suitable terrain, caves, cliff ledges, and rocky cavities may be exploited. In other areas nesting occurs where dense undergrowth is available, or where the site is protected by swampland. In the photograph mentioned above, the nest, a slight indentation in the ground, was centered in a large brush pile. Hollow logs or stumps, and abandoned buildings also provide protected nesting sites. Dark sites are preferred (Harrison 1978). There is some evidence that some sites may be reused from year to year (Kirk and Mossman 1998). Turkey Vultures will sometimes breed in loose aggregations with Black Vultures (Newton 1979). Two eggs are normally laid, a pattern confirmed by TBBA observers. The eggs are creamy white with highly variable spots and blotches in shades of brown. Incubation, by both sexes, is 38-41 days (Brown and Amadon 1968). The young, fed by regurgitation, are downy white with black heads, and are tended by both adults. They fly when 70-80 days old. An immature can be distinguished by its dark head and bill.
STATUS: The status of the Turkey Vulture is good. BBS records from 1966 to 1993 indicate in North America a slight increase in the population of 0.6 percent with some of the growth occurring because of the species expanding its northern range in Canada. In Texas BBS records for the same period show a 0.0 percent change in population (Bruce Peterjohn, BBS, pers. comm.). Despite the absence of confirmed breeding records by the TBBA for large areas of Texas, the BBS population figures over a nearly thirty year period make it clear that Turkey Vultures are successfully replenishing an already healthy population. That the population is stable may result in part from Texas being on a major flyway for migrating raptors. Between 12 October and 12 November 1992, 3,785 Turkey Vultures passed south through Anzalduas County Park in the lower Rio Grande Valley. In the spring between 11 March and 16 April 1993 at Bentsen Rio Grande State Park, 4,866 went north. This number is believed to be a record (Economidy 1994) and further suggests that the Turkey Vulture is doing well in Texas.
Text by Anthony Buckley (Posted 2006)
Literature cited.
Brown, L. and D. Amadon. 1968. Eagles, Hawks and Falcons of the World. McGraw-Hill. New York, New York.
Economidy, J. 1994. HMANA Hawk Migration Studies. February 1994. P.51. HMANA: New York, New York.
Harrison, C. 1978. A Field Guide to the Nest, Eggs, and Nestlings of North American Birds. Collins. New York, New York.
Kirk, D. A. and M. J. Mossman.1998. Turkey Vulture (Cathartes aura). In The Birds of North America, No. 339 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Newton, I. 1979. Population Ecology of Raptors. Buteo Books, Vermillion, South Dakota.
Oberholser H. C. and E. B. Kincaid, 1974. The Bird Life of Texas. University of Texas Press, Austin, Texas.
Pulich, W. M. 1988. The Birds of North Central Texas. Texas A &M University Press, College Station, Texas.
Sprunt, A. 1955. North American Birds of Prey. Harper and Brothers, New York, New York.
Warner, R. H. 1973. Birds of Big Bend National Park and Vicinity. University of Texas Press, Austin, Texas.