Responses to leopards are independent of experience in Guereza colobus monkeys

How primates learn to recognise the predatory species from their animate world is a largely unresolved problem. We conducted predator encounter experiments with wild Guereza colobus monkeys of the Sonso area of Budongo Forest, Uganda. The monkeys are hunted by crowned eagles and chimpanzees, but not leopards, which have been locally extinct for decades. Despite their unfamiliarity with this predator, monkeys reliably produced appropriate anti-predator behaviour to leopards, which was indistinguishable from that of a neighbouring population, where leopards are present. In both populations, monkeys produced the same vocal responses and predator-specific alarm calls, although leopard-naive monkeys were more inclined to approach when hearing a leopard than monkeys that were familiar with this predator. Control experiments showed that the monkeys' response pattern was not due to the effects of unfamiliarity or conspicuousness of the experimental stimuli. Natural selection appears to have endowed these primates with a cognitive capacity to recognise direct signs of leopard presence as inherently dangerous requiring specific anti-predator responses.