Accepted Manuscripts / Effect of human nuisance on the social ...
Effect of human nuisance on the social organization of large mammals: group sizes and compositions of seven ungulate species in Lake Mburo National Park and the adjacent Ankole Ranching Scheme
Christiane Averbeck, Martin Plath, Torsten Wronski & Ann Apio
Most ungulates in East African savannahs experience some form of human disturbance, like direct pursuit (hunting, poaching), habitat degradation, and competition with livestock. In many studies the impact of human activities on wildlife is assessed through census counts, i.e., by estimating population sizes or densities, but also the social organization of gregarious species can be affected. Using seven species of ungulates occurring in the Akagera Ecosystem, we compared grouping patterns (i.e., group sizes and compositions) of different group types (bachelor, all–female and mixed–sex groups) between sites that are situated inside a protected area, Lake Mburo National Park in Uganda, and the adjacent Ankole Ranching Scheme (ARS), an unprotected area with intense human pursuit. Differences in group sizes were detectible in only few cases, e.g., bachelor group size in eland increased on the ARS, which may be advantageous due to increased vigilance. However, pronounced differences in group compositions were found in numerous species and for different group types, for example, in eland and waterbuck (all group types), and topi, oribi and warthog (all–female and mixed–sex groups). We discuss that continuous monitoring of grouping patterns of these (and other) species may be a valuable approach to detect “subtle” effects of human nuisance even before an overall population decline can be observed.
Key words: domestic livestock, African ungulates, game ranching, poaching, social organization, Akagera Ecosystem