Bonobo population density and number of adult individuals in 2011, 2012, 2013, respectively, as estimated with Distance 6.0.

We modelled data with a half normal cosine function and used a truncation distance of 35 m. We obtained an effective strip width (‘ESW’) of 19.1 m and a mean probability of detection of 0.55. %CV =  Coefficient of Variation for the density estimate. D = density estimate. D LCL =  Lower confidence limit (95%) of the density estimate. D UCL =  Upper confidence limit (95%) of the density estimate. N =  community size estimate (number of adults). N LCL =  Lower confidence limit (95%) of the community size estimate. N UCL =  Upper confidence limit (95%) of the community size estimate (1the global estimate was derived by weighting data with the area of the three parts of the study site).