Nest ecology and conservation of western chimpanzees (pan troglodytes verus) in Gola Rainforest National Park, Sierra Leone

A nest survey of western chimpanzees (Pan troglodytes verus) was conducted in Gola Rainforest National Park (GRNP) and the surrounding community forest in eastern Sierra Leone. The aim was to investigate chimpanzee nest ecology with a focus on nesting tree species selection. Field data were gathered between September 2015 and June 2016 during a nest census along 89 transects covering 158 km—104 km within the protected area and 54 km outside. We documented a total of 96 nests in 54 nest groups. Chimpanzees preferred to nest in areas of primary forest with low or no undergrowth. Twenty-two tree species were used for nesting trees. Tree selection was not random, with chimpanzees showing preference for a subset of tree species. Heritiera utilis, a common timber tree, was the species most selected, with 23% of all nests. The top six tree species accounted for 70% of all nests encountered. Chimpanzees showed a preference for nesting within the boundaries of the protected area and, on average, nested at a higher elevation (20.4 m above ground) than has been found in other studies in West Africa. Our results indicate that P. t. verus in our study area tended to avoid the human-disturbed community forests. These findings will be useful to inform conservation practices both inside and outside the park, as well as community forestry and law enforcement initiatives.