Wheeling sedately over forests and farmland, the Turkey Vulture is the most widely distributed vulture in the New World. This familar and widespread species breeds from southern Canada to southernmost South America. Of the 3 North American races, the eastern and Mexican forms are only partly migratory. Vast numbers of the western race migrate to Central and South America, where they coexist with resident subspecies and other vultures.
Almost exclusively a scavenger (Cathartes means “purifier”), this species rarely kills small animals or invertebrates. Nearly all reports of vultures killing livestock are attributable to the more aggressive, closely related Black Vulture (Coragyps atratus). The Turkey Vulture tends to forage solitarily, but individuals attracted to other feeding vultures often congregate at carcasses. Communal Turkey Vulture roosts facilitate group foraging and social interactions; the roosts range in size from a few birds to several thousand, often include Black Vultures, and are sometimes “advertised” by spectacular evening flights.
The Turkey Vulture's highly developed olfactory sense enable individuals to locate concealed carcasses beneath a forest canopy. Black Vultures may follow Turkey Vultures to food and displace them; in response, the Turkey Vulture specializes on small food items that can be eaten quickly.
The Turkey Vulture's preferred habitat includes farmland with pasture and abundant carrion close to undisturbed forested areas for perching, roosting, and nesting. This species nests in dark recesses beneath boulders, on cliff ledges, in hollow trees, logs, and stumps, and in abandoned buildings. In addition to being prone to accumulate pesticides and other contaminants, the Turkey Vulture has a propensity to feed in agricultural and roadside habitats, making it vulnerable to accidental trapping, collisions, electrocution, shooting, and the ingestion of lead from animals that have been shot. Its former persecution as a potential vector of livestock disease or as a predator of young animals has largely ceased, since these contentions have proved false. However, the Turkey Vulture is the main avian species causing damage and fatalities in military aircraft collisions in the United States.
Tolerant of human activity and adaptable in its diet and choice of nest sites, this species has fared well in our changing landscapes; its populations are generally stable or increasing.
Although breeding studies have been undertaken in parts of its range (e.g., Wisconsin; Mossman and Hartman 1992), surprisingly little is known about the Turkey Vulture's breeding biology or its ecology in nonbreeding areas (e.g., specific wintering locations for North American races). Because of its social organization and habit of communal roosting, the species has been the focus of several recent studies testing if individuals can learn the location of food from other flock members (e.g., Prior and Weatherhead Prior and Weatherhead 1991a, Prior and Weatherhead 1991b, Buckley 1996). Its use of home range and forag-ing habitat has been described quantitatively in southern Pennsylvania and northern Maryland (Coleman and Fraser 1989c), but such information is lacking over much of the range. Recent work in South America suggests that North American Turkey Vultures compete with smaller resident subspecies in some parts of their nonbreeding ranges (Kirk and Currall 1994, Kirk and Gosler 1994, Kirk and Houston 1995).