A comparison of two mountain gorilla habitats in Bwindi Impenetrable National Park, Uganda

Abstract

Bwindi Impenetrable National Park, Uganda, is a small protected area (331 km2) within which there is large climatic and altitudinal variation. Therefore we compared habitat types and forest composition between two locations to investigate differences that may influence ecological conditions for large mammals, including endangered mountain gorillas. We demonstrate that there is considerable intersite variation in habitat types and spatial and temporal availability of vegetation resources of which the most apparent are the differences in species composition of plants and fruit availability. Buhoma (the lower altitude site) has a greater diversity of plant species and higher tree and shrub densities, yet has a much lower density of herbaceous vegetation eaten by gorillas compared with Ruhija. Fruit availability is significantly higher throughout the year in Buhoma compared with Ruhija. Both sites exhibit seasonal variation in fruit availability although they do not follow the same seasonal pattern, perhaps because of inherent asynchronous phenological differences amongst individual tree species. The results of this study are important because distribution and abundance of both terrestrial herbaceous vegetation and fruit resources are believed to influence aspects of feeding ecology for large mammals.

Detecting intraannual dietary variability in wild mountain gorillas by stable isotope analysis of feces

“…There is no consistent relationship between home range and fruit feeding among the Bwindi gorillas (57), suggesting this pattern of isotope variability is not likely driven by geography. Additionally, although fruit feeding among the Bwindi gorillas may be driven by changes in fruit availability throughout the year (59), it is not related to rainfall seasonality (62). Dry mass fruit intake is similar to previous fruit feeding estimates for Bwindi gorillas, which exceeds observed fruit feeding in Virunga mountain gorillas (7,(57)(58)(59)61).…”

“…Lowland gorillas (Gorilla gorilla) consume fruit more regularly than mountain gorillas (2,9). Differences in fruit intake among gorilla populations likely reflect spatiotemporal variation in the distribution of fruit species across habitats (59,62). Chimpanzees eat fruit more consistently year round, even when fruit availability is low (7)(8)(9).…”

Dynamics of forest cover conversion in and around Bwindi impenetrable forest, Southwestern Uganda

“…The protected forest has a unique eco-system with diverse gene reserves with worldwide interest. It is most popular for gorilla tourism attraction (Nkurunungi et al, 2004). The area is of particular concern due to the rapid land conversion practices and sensitivity to human impact.…”

Feeding Competition and Agonistic Relationships Among Bwindi Gorilla beringei

“…Fruit, which is unevenly distributed in time and space, is a common food item in the diets of all gorillas, except Karisoke mountain gorillas (Gorilla beringei beringei) in the Virunga Volcanoes of Uganda, Rwanda, and Democratic Republic of Congo (Doran et al 2002;Ganas et al 2004;Masi et al in review;Nkurunungi, 2003;Rogers et al 2004;Yamagiwa et al 2003). They live at an ecological extreme of gorilla habitat (high altitude of >2500 m); their diet consists almost entirely of highly abundant, evenly distributed herbaceous vegetation; and they incorporate only a negligible quantity of fruit into their diet (Watts 1984).…”