|Chimpanzees with offspring, Photo credit: flickr user Valerie|
Researchers collected fecal samples and genotyped those samples from 2011-2013. They then used models to determine the number of individuals. This noninvasive method is more accurate than counting the number of nests chimpanzees make at night in order to determine the number of individuals. (Chimpanzees make nests out of branches and forest materials every night that they sleep in. See a video here.) Using this method, they were able to determine that there are at least nine communities, each with anywhere between eight to thirty-three individuals. Because not all areas of the unprotected corridor were not sufficiently sampled in this study, it is possible this is a conservative estimate, and numbers may be even higher.
McCarthy and colleagues point out that chimpanzees exhibit a great deal of behavioral flexibility, which likely accounts for how they've coped with a less-than-ideal environment. Chimps are omnivores and can adapt their diet if they need to, including human-cultivated foods. Provided a lack of pressure from hunting, it is worth considering these stretches of land that previously may have been overlooked as viable areas worthy of conserving. The next steps will be understanding just how the chimps are doing so well in this habitat. What behavioral changes are they making?
Links of interest:
IUCN Redlist page on chimpanzees
Map showing current range of chimpanzees
The fate of western lowland gorillas and chimpanzees over the next decade
How human are chimps?
NPHC 2014 provisional results report. Uganda Bureau of Statistics, Kampala; 2014.
Oates, J.F., Tutin, C.E.G., Humle, T., Wilson, M.L., Baillie, J.E.M., Balmforth, Z., Blom, A., Boesch, C., Cox, D., Davenport, T., Dunn, A., Dupain, J., Duvall, C., Ellis, C.M., Farmer, K.H., Gatti, S., Greengrass, E., Hart, J., Herbinger, I., Hicks, C., Hunt, K.D., Kamenya, S., Maisels, F., Mitani, J.C., Moore, J., Morgan, B.J., Morgan, D.B., Nakamura, M., Nixon, S., Plumptre, A.J., Reynolds, V., Stokes, E.J. & Walsh, P.D. 2008. Pan troglodytes. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>.