The 2020 elephant die-off in Botswana

Abstract

The cause of deaths of 350 elephants in 2020 in a relatively small unprotected area of northern Botswana is unknown, and may never be known. Media speculations about it ignore ecological realities. Worse, they make conjectures that can be detrimental to wildlife and sometimes discredit conservation incentives. A broader understanding of the ecological and conservation issues speaks to elephant management across the Kavango-Zambezi Transfrontier Conservation Area that extends across Botswana, Namibia, Angola, Zambia, and Zimbabwe. Our communication addresses these. Malicious poisoning and poaching are unlikely to have played a role. Other species were unaffected, and elephant carcases had their tusks intact. Restriction of freshwater supplies that force elephants to use pans as a water source possibly polluted by blue-green algae blooms is a possible cause, but as yet not supported by evidence. No other species were involved. A contagious disease is the more probable one. Fences and a deep channel of water confine these elephants' dispersal. These factors explain the elephants' relatively high population growth rate despite a spell of increased poaching during 2014-2018. While the deaths represent only ~2% of the area's elephants, the additive effects of poaching and stress induced by people protecting their crops cause alarm. Confinement and relatively high densities probably explain why the die-off occurred only here. It suggests a re-alignment or removal of fences that restrict elephant movements and limits year-round access to freshwater.

Keywords: Botswana; Conservation; Die-off; Dispersal; Elephants; Fences.

Figure 1. Maps to illustrate administrative and natural boundaries in Ngamiland, northern Botswana.

While most of the region has an IUCN status, the NG11 and NG12 administrative blocks have no protected status (A). The Seronga area (NG11, NG12, and a part of NG13) is cut off from the surrounding landscape by either deep water of the Okavango River and Delta (blue) or veterinary or border fences (dashed lines) (B). The shape files for the protected areas were sourced from the World Database on Protected Areas (https://www.protectedplanet.net/en) and for the Okavango Delta from the ESA Climate Change Initiative (Land Cover project 2017).

Figure 2. The pathways of five elephants in the Seronga area (NG11, NG12, and NG13) from October 2003 to November 2006 and eight elephants roaming beyond Seronga that we tracked from November 2004 to March 2010.

The elephants in Seronga did not cross the veterinary fence (dashed lines) or the Okavango Panhandle, and neither did the elephants beyond the boundaries separating Seronga and the adjacent areas in Botswana, Namibia, Angola, and Zambia. Basemap Source: ESRI, MAXAR.

Figure 3. Time series of elephant population estimates from 1996–2018 and exponential fit (weighted with the inverse of variances) in the Seronga area (NG11 and NG12) (A) and the NG14 to NG24 adjacent areas (B).

Error bars represent the 95% confidence interval.