Landscape-level changes to large mammal space use in response to a pastoralist incursion

Abstract

Pastoralists and their livestock have long competed with wildlife over access to grazing on shared rangelands. In the dynamic 21st century however, the configuration and quality of these rangelands is changing rapidly. Climate change processes, human range expansion, and the fragmentation and degradation of rangeland habitat have increased competition between pastoralist livestock and wildlife. Interactions of this type are particularly apparent in East Africa, and perhaps most obvious in northern Kenya. In 2017, following months of intense drought, a pastoralist incursion of a protected area (Loisaba Conservancy) occurred in Laikipia County, Kenya. An estimated 40,000 livestock were herded onto the conservancy by armed pastoralists where the cattle were grazed for approximately three months. Using 53 camera trap sites across the 226 km2 conservancy, we quantified spatial patterns in site visitation rates (via spatially-explicit, temporally-dynamic Bayesian models) for seven species of large mammalian herbivores in the three-month period directly before, during, and after the incursion. We detected significant changes in space use of all large mammalian herbivores during the incursion. Furthermore, these patterns did not return to their pre-incursion state in the three-month period after the pastoralists and their livestock left the conservancy. Thus, in addition to reduced site vitiation rates for these large mammalian herbivores, we also detected considerable displacement in response to the livestock incursion. Our results illustrate that pastoralist incursions can cause large-scale disruptions of wildlife space use, supporting the notion that livestock can competitively exclude large mammalian herbivores from grazing access. We discuss the implications of this research for applied management decisions designed to alleviate competition among wildlife and pastoralist livestock for the benefit of wildlife conservation and pastoralist well-being.