Wild Samango Monkeys, Cercopithecus mitis, Balance Risk and Opportunity to Interact with Novel Objects in Village Gardens

Abstract

Research suggests that wild animals in urban areas exhibit heightened behavioral flexibility when they encounter novel human-made objects, but most such studies compared responses in urban populations with those from disjunct populations in less disturbed environments. We therefore know little about intrapopulation variation in cognitive or behavioral flexibility under different conditions of anthropogenic exposure. Here, we investigate object exploration and behavioral flexibility in a single group of samango monkeys (Cercopithecus mitis) in an environment in which individuals forage in both gardens and natural forest. Over 2 months, we presented monkeys with novel, human-made objects in both natural and disturbed areas, varying the position of objects in trees to represent exposed or safer foraging zones. We video-recorded and analyzed interactions with these novel objects, assessing interaction times (an indicator of persistence), exploratory diversity (or motor diversity), and the occurrence of foraging innovations. Results from 67 interactions (29 in natural habitats and 38 in disturbed) indicate that samango monkeys exhibited a spatially complex response to novel objects: in contrast to that in other species, exploration diversity decreased significantly in anthropogenic environments, even as persistence remained largely static across contexts. Monkeys also exhibited foraging innovations by pulling on strings to bring objects closer. This may reduce exposure to danger, as string-pulling was most prevalent in the highest risk condition (ground level in human gardens). Significant intrapopulation variation in behavioral flexibility suggests that samango monkeys adjust the expression of problem-solving behaviors in relation to the degree of human disturbance in their immediate environment.