Cliff roost site selection of the endangered Cape Vulture Gyps coprotheres in the Eastern Cape province, South Africa

Abstract

Roost site preferences influence the spatial distribution of species. Large soaring birds often roost on cliffs and large structures, and thus are restricted to areas where safe take-offs and landings can occur. The cliff roosting preferences of the Cape Vulture Gyps coprotheres were explored for five juveniles and nine adult birds. Generalised linear mixed models (GLMM) were used to identify which features were considered favourable for cliff roosting sites. Roost density around colonies (breeding colonies for adults and natal colonies for juveniles) was calculated in predetermined buffer sizes and a GLMM was fitted to the data to investigate the effect of distance from colony and age. Both age classes of Cape Vultures showed a cliff roost preference for areas that were located closer to colonies, in protected areas and were of high topographical elevation with a southwest orientation. Cliff roost sites of a south aspect that had predominately east winds were also favoured. The highest density of roosts for juveniles and adults was located within 40 km from the breeding colony. The protection of roosting sites is an important consideration for conservation management particularly given the high concentrations of vulnerable birds.

Keywords: buffer sizes, conservation, roost density, roosting site, taille de zones tampons, conservation, densité de perchoirs, site de repos