The natural removal of ungulate carcasses, and the adaptive features of the scavengers involved

Abstract

The natural removal of ungulate carcasses was monitored on a variety of livestock farms and nature reserves in the Transvaal and southern Zimbabwe. 89 carcasses of different sized ungulates were placed or found on these sites, and 30 of these were observed from hides. The rate of decomposition of the carcasses was recorded as well as the behaviour of the scavengers involved. Carcass removal proceeds much faster on nature reserves because they have a greater variety of scavengers than the farms. Griffon vultures and spotted hyaenas are the primary scavengers on the reserves. The vultures remove most of the soft tissues, while hyaenas remove most of the skin and bone. On the farms griffon vultures are still the most efficient scavengers, but because they are shy, jackals and maggots are able to compete more successfully than in the nature reserves. The scavenging success of vultures is analysed in terms of their feeding behaviour, and social organization. The griffon vultures and the hooded vulture are considered to be successful scavengers, while lappet-faced and white-headed vultures are suggested as having alternative sources of food other than large ungulate carcasses. Spotted and brown hyaenas are the only carnivores that regularly and efficiently crush bones. Bone damage by hyaenas and hominids are compared with each other and found to be distinctly different. These differences relate primarily to the survival of long bone epiphyses, and are suggested to persist in fossilized bones. Therefore the agents of accumulation of fossilized bones found in caves should be identifiable from the survival pattern of the long bones. The roles hyaenas and griffon vultures perform in the nutrient cycle and in the spreading of disease are briefly discussed. The evolution of the major scavengers are considered in terms of their physical adaptations, social organization and foraging strategies.