Baboon and Vervet Monkey Crop-Foraging Behaviors on a Commercial South African Farm: Preliminary Implications for Damage Mitigation

Conflict between crop farmers and wild nonhuman primates is a worldwide conservation issue of increasing concern. Most of the research on wild primate crop foraging has so far focused on the conflicts with subsistence agriculture. Crop damage caused by primate foraging in large-scale commercial agriculture is also a major facet of human–wildlife conflict. Despite its increasing severity, there are very few published accounts of on-farm wild primate crop-foraging behavior or effective techniques to deter primates from field crops on commercial farms. To address this knowledge gap and identify some mitigation strategies, we used direct observation from a hide to collect behaviors and interspecific interactions between 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. Baboons caused the most crop damage, foraged on crops more in the mornings, and their rates of crop foraging were influenced primarily by natural vegetation productivity. Vervet monkey rates of crop foraging were primarily influenced by the presence of baboons. When baboons or vervets visited the farm, half of the visits did not involve crop foraging, and vervets were more likely to crop forage when they visited than baboons. Based on this preliminary study, we make recommendations for crop farmers to improve the effectiveness of current deterrent methods. These include increasing deterrent efforts when natural vegetation drops below a normalized difference vegetation index value of 0.32, especially during the hours before midday, chasing baboons and vervets farther from the farm rather than just out of crop fields, and increasing the perceived mortality risk of field guards. These recommendations should be evaluated to determine effectiveness before being adopted on a wider scale.