Trophic relations in a community of African rainforest carnivores

Abstract

The factors that promote ecological separation among closely related sympatric carnivores in tropical forests are poorly understood due to a paucity of field studies. Here, we report on community-wide food resource utilization patterns among eight co-existing carnivores in the Dzanga-Sangha Reserve, Central African Republic, based on a collection of 666 scats that were identified using a combination of methods, including thin-layer chromatography. Members of the assemblage took advantage of the diverse array of food resources characteristic of tropical forest habitats by adopting a variety of feeding strategies, such as carnivory, insectivory, frugivory, and piscivory. Broad-scale dietary separation was evident among most pairs, with only 6 of 21 exhibiting food niche overlaps that exceeded 50%. The marsh mongoose (Atilax paludinosus) and African civet (Civettictis civetta) were the most specialized with respect to food habits. Highest trophic overlaps were evident between the most carnivorous [leopard (Panthera pardus) and golden cat (Profelis aurata)] or insectivorous [mongooses (Herpestes naso and Bdeogale nigripes)] species. Unlike other animal groups, species richness of the food resource base was not a key factor structuring this rainforest community. Stronger roles were instead played by the size diversity and abundance of mammalian prey, and the perhaps superabundant or at least highly renewable nature of insects. Ecological separation was further facilitated by some segregation along the spatial (habitat) and temporal (activity) niche dimensions. The average weight of prey taken by leopards was considerably lower than that in other African and Asian sites. Mammals weighing over 20 kg were taken rarely, while use of small (<5 kg) prey was unusually high, signaling either the relatively depauperate base of the former, or high level of abundance and/or profitability of the latter.