Diets of bonobos in the Congo Basin may be different depending on social factors and reproductive status within their communities. Researchers investigating the dietary patterns of these wild primates used stable isotope analysis to gain more insight into environmental and social adaptations in primate evolution.
“The study non-invasively investigates the dietary pattern of a community of wild bonobos over two years by using stable isotope analysis in hair and integrating long-term sociodemographic data,” says Vicky Oelze, an author of the study, which is published in PLOS ONE.
Environmental conditions and sociodemographic factors can make it difficult to study great ape diets. However, the steady ecological climate of the evergreen forests of the Congo Basin provides a stable habitat, allowing researchers to study apes’ dietary differences independently of food abundance.
During the two year study, Oelze and colleagues collected hair samples from 23 bonobos living south of the Congo River in the Congo Basin. They analyzed stable nitrogen and carbon isotopes found in the hair and in local plants eaten by bonobos. The results showed that male and female bonobos’ eat differently depending on the rank and phase of reproduction of the animal.
For male bonobos, only social rank may affect their diets. The researchers found low levels of nitrogen in hair from adolescent males, which are low-ranking and commonly excluded when meat is shared. This was not the case in females, though. Instead, nitrogen and carbon levels in hair from females varied with reproductive phase. This result probably reflects differing dietary needs during pregnancy, when a high-protein diet is needed, and during lactation, when energy demands increase for nursing and carrying offspring.
Although the researchers conducted a comprehensive study, they recommend that their findings be tested in other species of primates.
Research Article: Oelze VM, Douglas PH, Stephens CR, Surbeck M, Behringer V, Richards MP, et al. (2016) The Steady State Great Ape? Long Term Isotopic Records Reveal the Effects of Season, Social Rank and Reproductive Status on Bonobo Feeding Behavior. PLoS ONE 11(9): e0162091. doi:10.1371/journal.pone.0162091
Image Credit: Bonobos Eating Together by Eric Kilby via Flickr