Sharing fruit of Treculia africana among western gorillas in the Moukalaba-Doudou National Park, Gabon: Preliminary report

We report the first 18 observed cases of fruit (Treculia africana) transfer among western lowland gorillas (Gorilla gorilla gorilla) in Moukalaba-Doudou National Park, Gabon. The fruit transfer occurred during our observations of a habituated group of gorillas in 2010 and 2013. Pieces of the fruits were transferred among adults and immatures, and three cases involved a silverback male. Once an individual picked up a fallen fruit of Treculia africana, other members of the group approached the possessor, who laid pieces of the fruits nearby and tolerated the others getting them. Agonistic interaction was rarely observed between the possessor and the non-possessor. Only the silverback male seemed to force another gorilla, a subadult male, to relinquish the fruit on the ground. He tolerated an adult female taking a piece of fruit on his leg and copulated with her on the following days. From these preliminary observations, most interactions over the fruit of Treculia africana among western gorillas in Moukalaba were not active transfer by the possessor but probably passive sharing. They were not only interpreted as a means of acquiring foraging skills by immatures (Nowell and Fletcher 2006) but also similar to behaviors observed in chimpanzees and bonobos in various social contexts.