Nutritional composition of actual and potential insect prey for the Kasekela chimpanzees of Gombe National Park, Tanzania.

Humans, all great ape species, and some lesser apes consume insects. Insects can provide comparable nutritional yields to meat on a gram-for-gram basis and may serve as an important source of energy, fat, protein, minerals, and vitamins for hominoids. Although potential insect prey are abundant in ape habitats, patterns of insectivory are not consistent across species or populations. Efforts to understand these patterns are complicated by a lack of nutritional data. We collected samples of insects consumed by the Kasekela chimpanzee community of Gombe National Park, Tanzania, as well as of some insects found within the community range and ignored by these chimpanzees but known to be preyed upon by Pan elsewhere. We determined the gross energy (GE), estimated metabolizable energy (ME), fat, protein, fiber, and ash content of these samples following standard methodologies. We use these data to test the hypothesis that Kasekela chimpanzees choose insect prey (at least in part) based on energy and/or macronutrient content. On a fresh-weight, per-gram basis, the insect prey consumed by Kasekela chimpanzees had significantly higher fat and lower ash content than other assayed insects, and on a fresh-weight, per-foraging-unit ("per-insect," "per-dip," or "per-nest") basis were significantly higher in GE, fat, and protein. On a per-gram basis, the assayed insects were generally comparable in energy and macronutrients to wild vertebrate meat. We conclude that Kasekela chimpanzees do favor insects that are high in energy, fat, and protein, and that the potential macronutrient yields from some forms of insectivory are not trivial.