Same-site multiple releases of translocated white rhinoceroses Ceratotherium simum may increase the risk of unwanted dispersal

Abstract

The Near Threatened white rhinoceros Ceratotherium simum went extinct in Botswana during the 20th century because of poaching. Several attempts have been made to reintroduce the species. From 2001 to 2003 four batches (a total of 32 individuals) of white rhinos were released in the Moremi Game Reserve. All were fitted with transmitters, ear notched and monitored on a regular basis. Rhinos released in the last batch moved significantly further from the release site compared to early batches. Six female rhinos from the last batch dispersed out of the Reserve. Activity area (95% minimum convex polygon; MCP) sizes decreased with years after release and increasing density of rhinos but only density had an effect on the core area (50% MCP) sizes. We conclude that the number of rhinos present in the area of release should be carefully considered before further individuals are released. When released in an area with rhinos that have established territories, the newly reintroduced individuals may be forced to disperse. If other areas of suitable habitat are available elsewhere in the same protected area, animals should be released at different sites to avoid unwanted long-term dispersal and to use the inverse density-dependent activity area sizes to maximize the rhino population in an area.