Factors affecting the ratio of lions (Panthera leo) to spotted hyaenas (Crocuta crocuta) in protected areas of Africa : competition and/or available prey
This study attempted to determine if competition was an important influence on the behaviour, distribution and abundance of lion and hyaenas. Complementary contrasting approaches were adopted, an intensive study in two areas, and a comparison among protected areas. The behaviour of lions and hyaenas was compared in two contrasting ecosystems. Matusadona National Park. MNP (Zimbabwe) and Liuwa Plains National Park. LPNP (Zambia). MNP is a closed woodland habitat dominated by resident population of buffalo and impala. LPNP is an open floodplain system dominated by migratory populations of wildebeest and zebra. MNP had a greater ratio of lions to hyaenas (2: 1) whereas in LPNP, hyaenas considerably outnumbered lions (18:1). The study also compared data from 13 Protected areas of Africa that differed in terms of habitat, available pre, size and human influence. In MNP there was no evidence of competitive avoidance behaviour by either species despite a considerable overlap in diet. Both species prey predominantly on buffalo and impala. There was evidence that each species was extending its niche to utilise prey species that would be uneconomic for the other species to use facilitating co-existence. The home ranges of the two species overlapped considerably and the location and size of their home ranges were similar. However, the study was not able to measure temporal distribution and the two species may have been avoiding each other by using the same areas of the park at different times. Further analysis of the responses of the two species to an increase in the population of buffalo, the main prey species of the park indicated that lions might have indirectly affected the hyaenas in the park, as the hyaena population decreased with an increase in the lion population. In the same park, more evidence of an adverse competitive effect was observed when the response behaviour of the two predators to a simulated prey resource (pre-recorded squealing pigs combined with a smelly bait) was compared. Lions responded as expected in areas of high prey density, whereas hyaenas responded more in areas with low prey densities and low visibility of prey suggesting that they were avoiding lions. In contrast, hyaenas in LPNP responded to the simulated resource in areas of high prey densities. The response behaviour of lions did not differ between the two Protected areas despite the fact that lions were outnumbered in LPNP and numerically dominant in MNP. This supports the hypothesis that a larger body size may enable lions to offset the effects of competition.