Negative interactions between crop farmers and wild primates are an issue of significant concern. Despite many crop farmers using field guards as a method of crop protection against foraging primates, there are very few published accounts of how effective this technique is and how it might be improved. To bridge this knowledge gap, we used direct observations from a hide to collect the behaviors of field guards, chacma baboons (Papio ursinus; baboons), and vervet monkeys (Chlorocebus pygerythrus; vervets) foraging in a 1-ha butternut squash (Cucurbita moschata) field for 4 months (May to August) in 2013 on a 564-ha commercial farm in the Blouberg District of South Africa. Only half of the crop-foraging events were chased by field guards, with vervets being chased much less frequently than baboons. Guards responded more often to events with greater primate numbers and to those that occurred earlier in the day. Guard delay in responding to crop-foraging events and baboon delay in responding to the guard both increased in the low productivity season. Baboon response delay also increased with more animals involved. Based on this case study, we suggest recommendations to improve the effectiveness of field guarding. This includes implementing an early warning alarm system, shortening field guard shifts, increasing guard numbers during the morning and low productivity season, and increasing the perceived fear of field guards, potentially by employing male guards or providing uniforms and deterrent accessories. Further evaluation in other local contexts will help determine how these findings can be adopted on a wider scale
