This 2011 dung survey provides an update of the 2006 elephant population estimates for the Okapi Faunal Reserve. Using the same estimates of dung decay, the elephant population declined by 37 percent over the 5 year period.
Source:Vosper, A., Masselink, J., and Maisels, F. (2012). 'Great ape and human impact monitoring in the Okapi Faunal Reserve, Democratic Republic of Congo'. Kinshasa, Democratic Republic of Congo: Wildlife Conservation Society RFO Program. 55 pp.