Foraging strategies as a function of season and rank among wild female chimpanzees (Pan troglodytes)

Among mammals, female reproduction is generally thought to be food limited, and dominance should theoretically afford high-ranking females with access to better food resources. Although the importance of dominance rank among female chimpanzees (Pan troglodytes) has been debated in the past, mounting evidence suggests that rank is very important among females (P. t. schweinfurthii) at Gombe National Park, Tanzania. In this study, we investigated the influence of season and dominance rank on female foraging strategies. We found that high-ranking females spent less time foraging and tended to have a narrower diet breadth and higher diet quality than subordinate females. In this way, subordinate female foraging strategies were consistent with how females in general adapted to periods of food scarcity. The results of this study therefore suggest that low-ranking females may face persistent food scarcity as a result of interference food competition. We also provide evidence that subordinates may forage less efficiently because they occupy lower quality habitats or avoid associating with dominant females in shared areas.