Sample-based estimates of elephants in Kruger National Park, South Africa

Abstract

Increasing trends in elephant population numbers in South Africa contrast those in most other range states. Most of South Africa's elephants occur in Kruger National Park (Kruger). Elephant population estimates and trends in these are key aspects of evaluating their conservation status. Authorities in Kruger traditionally made use of elephants observed during total aerial surveys. This approach, however, has no measures of precision of the population estimates. Total aerial surveys also assume that sample errors and various biases have negligible impact on population estimates. We aimed to demonstrate and explore a sample-based methodology to obtain the most reliable population estimates and trends. Total and sample aerial surveys of elephants were simultaneously used to develop sample-based estimates with confidence intervals for the Kruger elephant time series. During 2020, sample errors resulted in an approximately 15% underestimate of the number of elephants in Kruger. The aerial survey that accounted for sample errors estimated 31 324 elephants (95% CI: 28 457–34 191) present in Kruger. Comparison with the 2013 sample-based estimate predicts annual exponential growth of 5.3% (95% CI: 3.7–7.0%). Correct estimates with precision are important to inform assessments of the conservation status of elephants and how this may change.