We used artificial food patches to test effects of predation risk on foraging behavior of free-ranging Sykes’ monkeys (Cercopithecus albogularis erythrarchus) under the risk of predation by leopards (Panthera pardus), crowned eagles (Stephanoaetus coronatus) and black eagles (Aquila verreauxii). We predicted that the monkeys would 1) harvest more food from patches placed in trees than from patches on the ground, 2) forage more in food patches at greater heights in trees, 3) forage less on the ground when their sight lines were blocked by curtains than when they were not and 4) in a 60m x 60m landscape grid, forage more from patches that allowed easy access to trees. To test these predictions, we measured giving up densities (GUDs) of peanuts from provisioned food patches along vertical and horizontal landscapes in Sykes’ habitat. Species and time of foraging were confirmed using motion-sensitive cameras.
Only Sykes’ monkeys used the food patches, and foraging took place primarily between 7am and 1pm. Along the vertical landscape axis, GUD data supported our hypotheses that the monkeys would forage more at greater heights. Along the horizontal landscape axis, GUD data did not differ significantly between locations. We conclude that along the vertical landscape of fear, the canopy of trees provides the greatest safety, and ground presents the most predation risk. Given that ground equates with fear for Sykes’ monkeys, all locations throughout the ground landscape, at this scale, create the same amount of risk. We discuss the relative benefits of patch use as a method of studying primate ecology.