Biology Of Vultures, New World Vultures, Old World Vultures
Vultures are large birds of prey specialized to scavenge the bodies of dead animals. Species of vultures are assigned to two families in the order Falconiformes. The vultures of the Americas include seven species in the family Cathartidae. The vultures of Eurasia and Africa, numbering 14 species, are specialized members of the Accipitridae, a family that also includes hawks and eagles. The Cathartidae and the Accipitridae are not closely related.
Species of New World vultures
The most widespread vulture in the Americas is the turkey vulture (Cathartes aura), which ranges from southern Canada to South America. This species is migratory in the northern part of its range, often travelling in flocks of several hundred birds. The black vulture (Coragyps atratus) is another common species that breeds from southern North America to South America. The only other species of vulture in North America is the California condor (Gymnogyps californianus), an endangered species on the edge of extinction.
Other vultures occur in South America. The largest species is the increasingly rare Andean condor, which has a wingspread of 9 ft (3m), the largest of any living bird. This species, which can weigh more than 14 lb (6.5 kg), is also the heaviest flying bird.
A now-extinct American vulture was the very impressive Terratornis mirabilis, which had an enormous wing span of at least 16 ft (5 m). This species is known from fossils collected at the Rancho La Brea tar pits of southern California. Terratornis mirabilis may have still been around as recently as the end of the most recent glacial epoch, about 10,000-15,000 years ago. This enormous vulture may have become extinct as an indirect consequence of the disappearance at that time of many large species of mammals, an event that was likely due to the first colonization of the Americas by very effective human hunters.
New World vultures and man
As scavengers of dead animals, vultures provide an important ecological service. This has long been recognized by some human societies, which have viewed vultures as useful birds because they contribute to cleaning up some types of unpleasant refuse around habitations. However, in some places these views have recently changed and the presence of these scavengers is no longer encouraged. This has happened, for example, in parts of the Andes, where vulture dropping has been shown to contribute to the contamination of open reservoirs of drinking water with microbial pathogens.
Species of vultures have had great cultural significance to various groups of people. The Maya of Central America commonly used a hieroglyphic associated with the king vulture (Sarcoramphus papa) to signify the thirteenth day of each month, and this species also appears to have been a religious symbol. The Andean condor was also culturally important to indigenous peoples over large parts of its range.
Unfortunately, because of their feeding habits vultures are regarded with great distaste in some other human cultures. Until rather recently, vultures were erroneously thought to be responsible for spreading some important, contagious diseases of livestock, because they fed on the bodies of animals that had died of those maladies. Vultures have sometimes been shot or poisoned
in large numbers for this reason. One American farmer claimed to have shot 3,500 black vultures during a single winter, in an attempt to relieve himself and his ranch of this harmless bird, which he perceived as a pest. Fortunately, vultures are rarely treated this way in North America any more, although they are still persecuted in some other areas, usually by a few misguided people.
The California condor is a critically endangered species of vulture. This species was formerly widespread in North America, especially in the west. However, this slowly reproducing species has declined enormously in abundance because of hunting and poisoning, and until recently it only survived in a critically endangered population of a few birds in the San Joachin Valley of southern California. In 1984, only 15 birds survived, and by 1986 there were only three adult male California condors. The few surviving wild condors are still under threat from shooting, lead poisoning following ingestion of lead bullets in scavenged carrion, and habitat degradation.
In 1987, no California condors remained in the wild. The handful of surviving wild condors were caught for use in a captive-breeding program, with the hope that enough birds could be produced to allow the eventual reintroduction of this endangered species into the wild. At that time the total population of the species was only 27 individuals, all in captivity. These last California condors are being used in a program of captive breeding supported by the United States Fish and Wildlife Service, and located at the San Diego Wild Animal Park and the Los Angeles Zoo. Fortunately, this breeding program is showing encouraging signs of success, and in 1991 the first, careful releases of California condors were made to a large ecological reserve created and managed for their benefit in southern California.
The California condor remains a critically endangered species, but there is now guarded optimism for its longer-term prospects of avoiding extinction.
- Andean condor (Vultur gryphus). The largest flying bird. Resident of the Andes.
- Turkey vulture (Cathartes aura). Highly developed sense of smell. Ranges from southern Canada to Tierra del Fuego. Reportedly declining population on the southern plains. Eggshell thinning has been a widespread problem. Today the populations appear stable.
- Yellow-headed vulture (Cathartes burrovianus). Resident of Mexico, Panama, and the lowland areas of South America.
- Greater yellow-headed vulture (Cathartes melambrotus). Found in several regions of northern South America.
- Black vulture (Coragyps atratus). Resident of middle North America to South America. Winters in North America. Loss of suitable tree cavities due to fire control has been a problem, as has eggshell thinning as a result of pesticide use. The population has expanded in the northeastern United States, but declined in the Southeast (possibly due to a loss of nesting sites in hollow trees).
- King vulture (Sarcorhamphus papa). Striking bird with pinkish-white plumage and black flight feathers. Some records suggest this bird may once have been a resident of Florida. Today it is a rare resident of tropical America.
- California condor (Gymnogyps californianus). Resident of North America. On the verge of extinction, now an endangered species. A captive breeding program introduced in 1987 has met with some success, and hopes now exist that a wild population may again be re-established.
- Vultures - Biology Of Vultures
- Vultures - New World Vultures
- Vultures - Old World Vultures
- Other Free Encyclopedias