The Steady State Great Ape? Long Term Isotopic Records Reveal the Effects of Season, Social Rank and Reproductive Status on Bonobo Feeding Behavior

• Published in: PloS one Vol. 11; no. 9; p. e0162091
• Main Authors: Oelze, Vicky M, Douglas, Pamela Heidi, Stephens, Colleen R, Surbeck, Martin, Behringer, Verena, Richards, Michael P, Fruth, Barbara, Hohmann, Gottfried
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14-09-2016; Public Library of Science (PLoS)
• Subjects: Analysis; Animal behavior; Animal reproduction; Animals; Apes; Biology and Life Sciences; Breastfeeding & lactation; Carbon isotopes; Carbon Isotopes - metabolism; Climate models; Diet; Diet - psychology; Earth Sciences; Ecological conditions; Ecology; Endangered & extinct species; Environmental conditions; Feeding behavior; Feeding Behavior - physiology; Feeding Behavior - psychology; Female; Females; Foliage; Food; Food availability; Food habits; Gender differences; Hair; Hierarchy, Social; High protein diet; Hominids; Human ecology; Infants; Isotopes; Lactation; Life history; Male; Males; Medicine and Health Sciences; Monkeys & apes; Neurosciences; Nitrogen; Nitrogen Isotopes - metabolism; Nutritional requirements; Pan paniscus; Pan paniscus - physiology; Pan paniscus - psychology; People and Places; Physical Sciences; Physiological aspects; Physiological effects; Physiological factors; Pregnancy; Primates; Rain forests; Rainforests; Reproduction - physiology; Reproductive status; Research and Analysis Methods; Seasonal variations; Seasons; Social aspects; Social behavior; Social classes; Social interactions; Social rank; Social status; Sociodemographics; Stable isotopes; Terrestrial environments; Tracers (Biology); Values; Congo Basin; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0162091

Dietary ecology of extant great apes is known to respond to environmental conditions such as climate and food availability, but also to vary depending on social status and life history characteristics. Bonobos (Pan paniscus) live under comparatively steady ecological conditions in the evergreen rainforests of the Congo Basin. Bonobos are an ideal species for investigating influences of sociodemographic and physiological factors, such as female reproductive status, on diet. We investigate the long term dietary pattern in wild but fully habituated bonobos by stable isotope analysis in hair and integrating a variety of long-term sociodemographic information obtained through observations. We analyzed carbon and nitrogen stable isotopes in 432 hair sections obtained from 101 non-invasively collected hair samples. These samples represented the dietary behavior of 23 adult bonobos from 2008 through 2010. By including isotope and crude protein data from plants we could establish an isotope baseline and interpret the results of several general linear mixed models using the predictors climate, sex, social rank, reproductive state of females, adult age and age of infants. We found that low canopy foliage is a useful isotopic tracer for tropical rainforest settings, and consumption of terrestrial herbs best explains the temporal isotope patterns we found in carbon isotope values of bonobo hair. Only the diet of male bonobos was affected by social rank, with lower nitrogen isotope values in low-ranking young males. Female isotope values mainly differed between different stages of reproduction (cycling, pregnancy, lactation). These isotopic differences appear to be related to changes in dietary preference during pregnancy (high protein diet) and lactation (high energy diet), which allow to compensate for different nutritional needs during maternal investment.