Crab-fishing by chimpanzees in the Nimba Mountains, Guinea

Abstract

The significance of aquatic food resources for hominins is poorly understood, despite evidence of consumption as early as 1.95 million years ago (Ma). Here we present the first evidence of a nonhuman ape habitually catching and consuming aquatic crabs. Chimpanzees (Pan troglodytes verus) in the rainforest of the Nimba Mountains (Guinea) consumed freshwater crabs year-round, irrespective of rainfall or ripe fruit availability. Parties of females and offspring fished for crabs more than predicted and for longer durations than adult males. Across months, crab-fishing was negatively correlated with ant-dipping, suggesting a similar nutritional role. These findings contribute to our understanding of aquatic faunivory among hominins. First, aquatic faunivory can occur in closed forests in addition to open wetlands. Second, aquatic fauna could have been a staple part of some hominin diets, rather than merely a fallback food. Third, the habitual consumption of aquatic fauna could have been especially important for females and their immature offspring. In addition to providing small amounts of essential fatty acids, crabs might also be eaten for their micronutrients such as sodium and calcium, especially by females and young individuals who may have limited access to meat.

How to measure chimpanzee party size? A methodological comparison

“…Chimpanzees were encountered following traces and/or vocalizations. Parties were scored as female(s) only, female(s) and offspring, male(s) only, and mixed sex (following Koops et al 2019). When measured on the same day, parties were defined as separate parties when no overlap between individuals was observed, and when subsequent party observations around the same location were more than 1 hour apart.…”

Chimpanzees foraging on aquatic foods: algae scooping in Bossou

“…In a recent paper on the exploitation of aquatic fauna by chimpanzees, Kathelijne Koops and colleagues (Koops et al 2019) reported the first evidence of chimpanzees habitually catching and consuming aquatic crabs. Chimpanzees in the Nimba Mountains of Guinea consumed fresh-water crabs (Liberonautes lactidactylus and Liberonautes rubigimanus) year-round, irrespective of rainfall or ripe fruit availability.…”

Importance of subterranean fungi in the diet of bonobos in Kokolopori

“…Feeding behaviors on nonstaple food items can be particularly informative for behavioral ecologists, because the availability of these food items can influence individuals' health (e.g. Bergstrom et al, 2019, Koops et al, 2019), and movement patterns (e.g. Grueter et al, 2018, McNaughton, 1988, Potts et al, 2015).…”