Ranging behaviour of Cape Vultures Gyps coprotheres from an endangered population in Namibia

Abstract

The Cape Vulture (Gyps coprotheres) is an obligate cliff-nesting vulture endemic to southern Africa. Its range and population size have declined markedly over the last century. Namibia has just one colony, located on the cliffs of the Waterberg Plateau, with a population estimated to be eight adult birds, including two females. The species is regarded as Critically Endangered in Namibia, and establishing a secure breeding population may require intensive management. Data on movements, foraging range and behaviour of Cape Vultures, important in any management programme, have been lacking. Five adult males and one immature were captured near the Waterberg site and fitted with satellite-tracking devices. Only two of the adult vultures still roosted on the cliffs and only one of those exclusively; the other individuals roosted in trees. Three individuals were observed building and attending to nests in trees, and, for one of these, the partner was identified as an African White-backed Vulture (Gyps africanus). The foraging range of the adult birds was large compared with other studies of this species. Most foraging took place on freehold farms. All adults avoided areas of communally owned land where wild ungulates are uncommon, thus further decreasing their potentially available food supply. Two ‘vulture restaurants’, feeding sites specifically for vultures, within the foraging range of the adult birds accounted for a large proportion of their time spent on the ground. The ranging behaviour of adult vultures varied throughout the year, and was apparently related to their nesting behaviour.