Management by Science: Black Rhino Translocation Program

Translocation is a cornerstone of black rhino conservation in southern Africa. The governments of South Africa and Namibia have translocated hundreds of black rhinos, but no detailed studies using radiotelemetry have monitored the outcome. Mortality rates are unacceptably high during black rhino translocations, with many deaths attributed to post-release stress, long-distance dispersal, fighting, and injuries sustained when rhinos crash into reserve boundaries. The Applied Animal Ecology Division of CRES has devised a series of ecological and behavioral hypotheses to guide our approach to solving these conservation problems. To date, staff has studied the behavior and movements of more than 100 black rhinos, including 3 different subspecies, released into 20 different sites. There are answers to some problems, but solutions to other problems are still needed.

In one approach, staff has been studying aspects of the translocation outside its immediate control, such as the size and social environment present at receiver sites. This as been done through staff observations of radiotagged rhinos and by partnering with the Rhino Management Group to analyze data from over 400 translocated rhinos. A pre-existing population at the release site, for example, is associated with higher mortality rates (because residents kill the newcomers), leading to the recommendation that future translocations attempt to establish larger populations initially so that sequential translocations will not place the newcomers in peril.

Reserve size is another important factor. Results indicate that in reserves smaller than 44,00 acres (18,000 hectares), rhinos more frequently encounter key hazards associated with post-release mortality: fences and other rhinos. Future translocations should be to larger reserves or, where not feasible, rhinos should be monitored and managed closely to mediate these risks. In a second approach, the post-release environment was experimentally manipulated to try to reduce the factors causing mortality after translocation. To do this, active partnerships were created with the agencies responsible for translocation and the managers of the private reserves receiving rhinos. Behavioral ecological theory was used to guide this program. It was surmised that (1) rhinos in stable populations at much higher density rarely kill one another; (2) the post-release social environment differs primarily in that rhinos are not familiar with one another; and (3) escalated aggression must result from lack of familiarity.

Because communication is the mechanism by which familiarity is attained and because rhinos communicate primarily through scent (dung and urine), studies of chemical communication were initiated. A strategy was then devised for spreading dung to familiarize residents and newcomers with each other’s odors before encountering each other. In unoccupied reserves, a different problem was encountered: rhinos are slow to settle and therefore expose themselves to risks as they move around their environment searching for appropriate habitat. It is hypothesized that rhinos, like other solitary species, might be attracted to settle adjacent to other conspecifics, using the rule of thumb that the habitat must be good if other conspecifics are living there. Rhino dung was spread to attract translocated rhinos to suitable habitat for settlement. This strategy worked well, with most rhinos settling adjacent to areas spread with dung. These are a few of many examples of how science is applied to rhino conservation.