Ficus sp. and Musanga leo-errerae: coexistent keystone fruits for chimpanzees in Kalinzu forest Grace

Abstract

The composition of Ficus sp. and Musanga leo-errerae in Chimpanzees’ diet was investigated by faecal analysis and direct observation in the medium altitude forest of Kalinzu, along the albertine rift, south-western Uganda. The fruit availability of Ficus species showed significant variationswhile that of Musanga leo-errerae was consistent and significantly higher than that of Ficus (P = 0.053; t = )2.034) all year round. Their consumption was not opportunistic as no correlation existed between their fruit abundance and their occurrence in chimpanzee faecal samples ⁄ diet (Musanga leoerrerae: r = 0.153, P = 0.456; Ficus sp.: r = 0.039, P = 0.848). Results showed that Musanga leo-errerae and Ficus species seeds occurred in 80.2% and 67.2% respectively of the total 2635 chimpanzee faecal samples analyzed. Although there was no significant difference between chimpanzees party size that fed on Musanga leo-errerae and Ficus tree species, the rate of consumption was significantly different in the low (t = 3.835; P = 0.031) than the high fruiting season (t = 2.379; P = 0.063). Ficus sp. and Musanga leo-errerae genera function as coexistent keystone fruits for chimpanzees because they perfectly complement each other in terms of chimpanzees’ sustenance. This information has significant implications in the management of tropical forests like Kibale, Budongo, Bwindi Impenetrable, Gombe and Mahale inhabited by primate populations especially the endangered ones like the chimpanzee.