FOOD-REQUIREMENTS AND THE TIMING OF BREEDING OF A CAPE-VULTURE COLONY

Annual food requirements of a Cape Vulture Gyps coprotheres family, co mprising one nestling and two adult birds, and a breeding colony were estimated. A family required 226,1 kg meat during a nestling period of 136 days, and 524,4 kg annually. The greatest family food requirement s (average 1,98 kg/day) occurred between 60 and 100 days after hatchin g. The period between 60 and 100 days after hatching was the most crit ical period of food demands, because (a) this was the period of greate st nestling food requirements, (b) only one parent could be away from the nest at a time, and (c) daily family food intake was effectively c onstant due to temporal constraints on foraging. The estimated food re quirements of a breeding colony comprising 152 breeding pairs and 98 n onbreeding birds was 89 388 kg meat annually, and 36 892 kg during the nestling period, with the highest food requirements (302 kg/day) occu rring during September and October. In summer rainfall areas of South Africa, the highest numbers of wild ungulate and livestock mortalities occurred during September and October. It is suggested that, due to p hysical, physiological and environmental constraints on parent birds' ability to provide food, the breeding cycle of Cape Vultures is timed so that the period of greatest food consumption coincides with the per iod of greatest food availability.