Using molecular and observational techniques to estimate the number and raiding patterns of crop-raiding elephants

Abstract

Summary 1. Conflict between humans and animals, generated by behaviours like crop raiding, can represent a major threat to the survival and conservation of protected species. Crop raiding is an example where the conflict is assumed to be attributable to a small number of habitually raiding animals. NostudieshavesystematicallytestedthisassumptiononAfrican elephantsLoxodontaafricana. 2. In the greater Amboseli basin, in southern Kenya, we determined the number of elephants that come into conflict with humans through crop raiding, their gender, and their patterns of raiding. We tracked footprints, and observed elephants after they raided farms, and genotyped DNA extracted from faeces collected from raided farms. Using these data, we estimated the number of raiderswithasymptoticregression and countmodels. 3. We found that 241 elephants from several elephant populations in the Amboseli basin raided farms. Raiders were independent males; we detected no females raiding crops. Approximately 35% of the raiders were from the Amboseli elephant population, representing about 1⁄3 of the independent males in that population. Approximately 12% of raiders from the Amboseli elephant population werehabitual and wereresponsible for56% of elephant raiding events. 4. Synthesis and applications. Our results suggest that targeted elimination of habitual raiders could in theory reduce crop raiding. However, the large pool of occasional raiders, the availability of palatablecropsinareasofconflict,andthelinkbetweencrop-raidingandnaturalmaleforagingtactics, indicates great potential for recruitment of habitual raiders from this pool of occasional raiders. Furthermore, shooting of raiders as a strategy for reducing crop raiding carries a high risk of misidentifying habitual raiders. We suggest instead an ethical management strategy that uses remote monitoring of raiders as an early warning system for crop protection, and longitudinal studies to evaluate the development of habitual raiding.