The behaviour and ecology of African wild dogs, Lycaon pictus, in an environment with reduced competitor density
African wild dogs, Lycaon pictus, are competitively inferior to lion, Panthera leo, and spotted hyaena, Crocuta crocuta. Across ecosystems, lion have been shown to be the single most important cause of wild dog mortality and, although spotted hyaena do not appear to kill wild dogs as readily as lion, they act as kleptoparasites at wild dog kills. Many studies have highlighted the impact that interspecific competition has on wild dog populations. Some more recent studies have used models and computer simulations to suggest that high levels of interspecific competition may lead to local extinctions of wild dog populations. As wild dogs are highly endangered and largely restricted to the few protected wildlife reserves in Africa where lion and spotted hyaena typically dominate, a better understanding of the impact of interference competition from these two species on wild dog populations is important. A census of the wild dog, lion and spotted hyaena populations on Save Valley Conservancy (SVC) in the southeast lowveld region of Zimbabwe showed that its large predator guild had a unique structure. Typically, spotted hyaena are the most numerous large predator followed by lion, both of which outnumber wild dogs by a significant amount. On SVC, the wild dog population outnumbered the lion and spotted hyaena populations by a considerable amount. This was due to the lion and spotted hyaena populations occurring at densities that were significantly lower than other communities throughout Africa. These small populations of lion and spotted hyaena were unlikely to have had a significant competitive influence on the wild dog population on SVC. As a result, SVC provided a unique opportunity to study a population of wild dogs in an environment in which interspecific interference competition was significantly reduced. The wild dog population on SVC occurred at a mean estimated adult density of 0.014 km-2 during the study. This adult density was similar to other wild dog populations in Southern Africa and so contradicted the hypothesis that in the absence of competition wild dogs would occur at higher densities. Two possible reasons were given for this lower than expected density. First, the annual estimates of adult density increased in each year of the study so it was possible that the population was still growing. Second, the wild dog packs on SVC contained significantly fewer adults in them when compared to other populations. It was shown that wild dog packs occupy home ranges that are largely spatially exclusive. As the size of the wild dog pack home ranges were not significantly correlated with the density of interspecific competitors across ecosystems, a reduction in the adult pack size would lead to a corresponding reduction in the adult density. It was suggested that the small mean adult pack size on SVC was due to the absence of selective forces associated with interspecific competition that would act to increase adult pack size e.g. increased vigilance against predation and increased protection of kills. While the mean number of pups in the wild dog packs on SVC was not significantly different to other wild dog populations, the ratio of adults to pups was much lower on SVC than other populations. Again, this was thought to have been a direct result of the lack of interspecific competition on SVC. The positive relationship between the mean ratio of adults to pups in wild dog packs and the density of lion and spotted hyaena across ecosystems provided further evidence for this relationship. Recommendations are made to ensure the persistence of the wild dog population on SVC. These include monitoring the lion and spotted hyaena populations and, if necessary, preventing them from increasing to exceptionally high densities; To increase the efficiency of the vaccination programme for the domestic dog population in the communal lands surrounding SVC; To initiate dialogue with neighbouring commercial and communal livestock farmers in order to try and reduce the conflict between predators and livestock; To create greater awareness of wild dogs through education.