Feeding Consequences of Hand and Foot Disability in Wild Adult Chimpanzees ( Pan troglodytes schweinfurthii )

Abstract

Many wild primates experience long-term limb disability, and their ability to cope with disability has implications for survival and fitness. We quantified the arboreal feeding and postural behaviors of adult chimpanzees to study the consequences of physical limb disabilities. We collected behavioral data for a total of 8 mo on chimpanzees at Sebitoli, Kibale National Park, Uganda, focusing on the time spent feeding, common feeding tree species, body postures, and substrate use. Of the 51 chimpanzees we observed, 16 (31%) exhibited limb anomalies, which varied in form and severity. Disabled chimpanzees climbed as high as chimpanzees without disabilities and did not differ from nondisabled chimpanzees in the amount they used feeding tree species. Adult chimpanzees with severe hand disability spent significantly more time feeding than nondisabled individuals. In addition, manually disabled adults did not suspend themselves from branches during feeding as frequently as nondisabled adults and used larger substrates for gripping and sitting than nondisabled adults. These results indicate that disabled individuals compensate to carry out feeding activities in trees.

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