Population Survey

Within the Garamba Complex, researchers counted 679 and 676 elephants, of which 48 and 39 were assessed as being under one year of age, in 2019 and 2020, respectively, during a novel pair of Elephant Demographic Surveys (EDS). By combining fixed- and rotary-wing aircraft, as well as near real-time collaring data and analysis of historical distributions of a subset of individual elephants; canopy cover mapping; and multiple-angle photography, herds were strategically targeted, photographed, and counted over five days in late March and early April of both years. Measurements of availability bias, the primary source of quantifiable error in this survey, indicated correction factors of 1.01, 1.18, and 1.73 for habitats with open, shaded, and mostly closed canopies, respectively. This procedure ultimately yielded a potential error of approximately 62 individuals for the 2020 count, which was the only year for which error could be quantified. These counts of Garamba’s elephants, which demonstrate high precision with each other, indicate that after years of decline, Garamba’s elephant population is now plausibly stable at approximately 700 individuals. The counts are likely the most robust estimate to date of the minimum number of elephants present within the Garamba Complex at a given time. Given the unavoidably high availability bias in habitats with dense canopy cover, it is likely that there are still some elephants that were not accounted for during this survey, an inevitable challenge using aerial surveillance; additional monitoring methods, such as genomics and camera trapping, should therefore be introduced to include these elephants in future counts.