Chimpanzees (Pt verus) Change the Landscape of a Forest Fragment by Dispersing Cultivars Raided from Local Villages

Chimpanzees (Pan troglodytes verus) living in a forest fragment in the Tonkolili District of Sierra Leone exploit their anthropogenic habitat by raiding crops of the surrounding human communities. Over a three year period, we have documented – through observation, fecal analysis, and community reports – chimpanzees consuming cultivars such as mango (Mangifera indica), oil palm (Elaeis guineensis), groundnut (Arachis hypogaea), and guava (Psidium guajava). Local villages report chimpanzees taking cultivars from crop fields and bringing them into the forest. We therefore hypothesized that the chimpanzees disperse the seeds of these cultivars into the forest.

We sampled a 3 km2 plot within a forest fragment bordered by cultivated crop fields, and recorded the presence of each cultivar within the plot. In order to determine a possible animal dispersal vector, we discarded samples that fell within a 15 meter radius of a fruiting tree. Of the remaining seedlings (n=72), 71% fell within 2 meters of a chimpanzee created path or nest. Of these, the cultivars we recorded consisted of mango (69%), guava (17%), and groundnut (4%). Though there are other possible seed dispersers (humans, monkeys, other mammals, etc.), due to the proximity of these seedlings to chimpanzee trails and nests, along with community reports of chimpanzees transporting these crops into the forest and reports of local monkey populations only raiding unripe fruits, we conclude that chimpanzees are likely vectors of cultivar dispersal. Such results provide insights into the ecology of a chimpanzee habitat at the human-primate interface.