Composition of the diet of lowland gorillas at Lopé in Gabon.

This report describes the composition of the diet of lowland gorillas, Gorilla gorilla gorilla, at Lopé in central Gabon. This population inhabits mature evergreen tropical forest and is not habituated to human observers. Data were collected during 6 years of an ongoing long-term study, from feeding-trails and by direct observation, but mostly by fecal analysis. Gorillas ate 182 plant foods from 134 species and 36 families. The fruit diet was diverse: 95 species were consumed, most with succulent pulp, and some immature seeds were eaten. Fruit remains were recorded in 98% of dung. Vegetative parts of Aframomum and Marantaceae formed staple foods, as they were abundant, accessible, and available year-round. Soil and social insects were also ingested; remains of weaver ants were recorded in one third of feces. More foods have been recorded for gorillas at Lopé than elsewhere and this is the most frugivorous population studied so far.