Long-Term Habitat Use by Mountain Gorillas (Gorilla gorilla beringei). 1. Consistency, Variation, and Home Range Size and Stability
Author: Watts, D.P.
Source: International Journal of Primatology, Volume 19, Number 4, August 1998 , pp. 651-680(30)
Abstract:Mountain gorillas are highly folivorous. Food is abundant and perennially available in much of their habitat. Still, limited research has shown that single gorilla groups heavily used areas where food biomass and quality were relatively high and where they met daily nutritional needs with relatively low foraging effort. Also, ecological factors influenced solitary males less than groups with females. Long-term data on habitat use by multiple mountain gorilla social units and more extensive data on variation in food distribution, presented here, confirm that food distribution influences areal occupation densities across groups and over time. These data also confirm the group/solitary male distinction and show that food distribution became more important for one male once he acquired females. Groups used ≤25 km2, and inter-annual home range and core area overlap was often low. Annual home range and core area size varied considerably within groups and across years. It bore no simple relationship to group size and estimated group biomass. Core areas were biased samples of total home ranges and were relatively good foraging areas. One group abruptly shifted its home range in response to male mating competition. Home ranges of two others expanded from 1981 to 1987, though at a decreasing rate. Data on one such group, which varied considerably in size, are consistent with arguments that costs of scramble competition are low except in unusually large groups. Low site fidelity, low scramble costs, and high home range overlap should decrease the ecological costs of female transfer.
Document Type: Research Article
Affiliations: Department of Anthropology, Yale University, P.O. Box 208277, New Haven, Connecticut 06520
Publication date: August 1, 1998