Difference between revisions of "Cape griffon vulture"
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|Cape Griffon Vulture|
The cape griffon vulture (Gyps coprotheres) is a bird of prey from the subfamily Aegypiinae, the Old World vultures.
Cape griffon vultures are large and very vigorously built, with long and wide wings and a rather short and only slightly rounded tail. The species shows a very minimal sex dimorphism in size and weight, the males about 98% the size of the females. The body length is 38–45 inches, with a wingspan of 7.4–8.5 feet, and a body weight of 15–24 pounds.
Cape griffon vultures are a dirty tan above, with some dark spots. Below they are a light beige to tan in color, with hints of reddish-beige on the largest part of the trunk, the pelvic floor, and the upper and lower wings, with white making an irregular appearance throughout. The flight primary and secondary flight feathers are monochrome black-brown to gray-brown. The unfeathered skin of the face and neck as well as a small unfeathered area at the base of the beak are blue-gray. The large and strong beak, as well as the unfeathered parts of the legs and the toes, are blackish-gray, the guard-skin blue-gray. The iris is yellow to ivory. Both males and females are similarly colored.
Juveniles are significantly darker than adults, with the head and neck covered in down. Cape griffon vultures will not get the adult plumage until the age of 6 to 7 years.
In colonies and on carrion sites, the species is quite vocal, giving hissing sounds in conflicts with other vultures. In addition they have creeping, chattering and grunting sounds, as well as a panting shriek.
Range and habitat
The original range of the species covered large parts of southern Africa between about 18° S and 35° S. Today the distribution of the species is restricted to three disjointed subareas. The largest reaches from southern Zimbabwe through southeastern Botswana, northeastern South Africa and the extreme west of Mozambique to the middle and southeastern South Africa. Two small spreading islands are located in the north-west of Namibia and the southern tip of South Africa.
Cape griffon vultures prefer open landscapes, including grasslands and desert, up to an elevation of about 9,000 feet. They vertical or steep rock cliffs, ravines and similarly usable rock formations for rest and breeding, staying clear of wooded areas.
Food consists exclusively of fresh or already decaying carcass, especially the internal organs; the muscular meat as well as bone chips from medium to large mammals are eaten. In large parts of the breeding area where wild game is lacking, cape griffon vultures are dependent on dead livestock such as sheep, goats and cattle. The birds can tear open the skin of larger mammals with their powerful beaks; the long and predominantly bare neck ensures it's able to reach deep inside the carcass for the internal organs. The goiter can hold more than two pounds of meat.
The food search is carried out at altitudes between 150-1,500 feet or higher as they ride the thermals. The animals search directly for carrion on the ground, but also indirectly by the observation of ground-living predators and above all by the observation of other carnivorous birds in flight.
Cape griffon vultures are very sociable; they breed in small to medium-sized colonies with 5 to a maximum of 900 breeding pairs, rarely if ever breeding individually.
The nests are built on rock ledges, either in the open or under overhangs. They are small, with a diameter up to 40 inches and a height of 12 inches for a bird of this size, and consist of sticks and twigs, with grass, heather, fern and other plant material laid out for comfort. One or two eggs are laid in the period from April to January, with an incubation lasting from 53 to 59 days. The young birds leaves the nest after about 140 days.
The population of these birds has declined sharply since the beginning of the 1960s, and the range has also been considerably reduced. In 2013 the total population was estimated to be 9,400 individuals. The largest concentration of cape griffon vultures is in South Africa; in Botswana there are about 600 pairs, in Lesotho about 552 pairs, and in Mozambique 10 to 15 pairs. The species is completely extinct in Swaziland, while in Zimbabwe there is one localized concentration containing up to 150 nonbreeding individuals. In Namibia there were about 2000 cape vultures in the 1950s, reduced to only 10-15 nonbreeding individuals by 2000.
The species is exposed to a range of hazards in its entire range, with the main causes of decline unintended poisoning (i.e. poison traps set for different animals, with the vultures feeding on the carcasses); electric shock on power poles and towers; collision with power lines and cars; the reduction the stock of large game mammals; and human persecution and disturbances by humans in the breeding colonies. The IUCN classifies the Cape vulture as "endangered" due to the small total population and the continuing decline in the species.
- Ferguson-Lees, Christie; pp 122, 436
- Ferguson-Lees, James, and Christie, David A. Raptors of the World; Christopher Helm, London 2001.