Factors affecting the distribution patterns of zebra and wildebeest in a resource-stressed environment

Understanding the spatial dynamics of landscape use by free-ranging herbivores is integral for successful ecosystem management. We used binary logistic regression analyses to determine the relative importance of biotic, abiotic and human factors in influencing the distribution (presence ⁄ absence) of wild grazers on two Maasai ranches in Kenya’s Amboseli-Tsavo ecosystem. Both ranches had low grass biomass and suffered from regular droughts. We found that grazers consistently located themselves where grass biomass was highest, usually irrespective of grass quality, suggesting that forage quantity may be the limiting factor where grass biomass is generally low. The availability of surface water had no significant effect on the likelihood of grazers being present, even in the dry season.