A review of elephant aerial surveys, 2010 – 2022
By Scott Schlossberg1 & Michael Chase1* – Elephants Without BordersExecutive Summary In 2022, an aerial survey for African savanna elephants (Loxodonta africana) was conducted over the Kavango-Zambezi Transfrontier Conservation Area (KAZA) in southern Africa. KAZA is a 520,000-km2 network of protected areas in Angola, Botswana, Namibia, Zambia, and Zimbabwe. The aerial survey found that KAZA holds ~228,000 elephants, confirming that this is the world’s largest population of savanna elephants and a critical stronghold for this endangered species. In this report, we attempt to place the KAZA results in context by examining trends in elephant populations since the last set of KAZA-wide elephant surveys in 2014-2015. We also report new data on elephant poaching in Botswana. We were able to compare numbers of elephants on the KAZA survey with 2014-2015 surveys in Angola, Botswana, Namibia, and Zimbabwe. Overall, numbers of elephants did not change significantly between 2014-2015 and 2022, with an estimated growth rate of 1.2% per year. Carcass ratios, an index of elephant mortality rates, did increase significantly over that time period, growing from 8% to 11% and potentially indicating unsustainable mortality rates. We also examined recent population trends by individual country. In northern Botswana, overall elephant populations have not changed significantly since 2010. Between 2018, the date of the most recent survey prior to the KAZA survey, and 2022, elephant numbers have generally increased in national parks and other protected areas, especially in the Okavango Delta. Numbers have generally decreased in pastoral and agricultural areas. In the Okavango Panhandle, elephant populations have been roughly stable since 2010, in contrast to the Botswana government’s claim of 7.6% growth per year7. Elephant trophy hunting in Botswana resumed in 2019. Between 2018 and 2022, numbers of elephants decreased by 25% in areas that were open to hunting and increased by 28% in areas where hunting is not allowed. If these trends continue, the ability of Botswana to produce trophy-quality elephants in hunting areas may be in question. Carcass ratios have been steadily increasing in Botswana since 2010 and were near 12% in 2022, potentially indicating high mortality rates. Fresh/recent carcass ratios in northern Botswana were unchanged between 2018 and 2022. The 2018 survey was conducted during a period of high poaching activity, suggesting that mortality rates at the time of the 2022 survey were still high. Between October 2023 and February 2024, we located 56 poached elephant carcasses in northern Botswana, mainly west of Chobe NP. Many of these carcasses were in an area that we previously identified as a poaching “hotspot” in 2018-2019. The area monitored for poaching in 2023-2024 is a small fraction of the total elephant range in northern Botswana, so the 56 carcasses found could indicate a wider problem with poaching. In southeast Angola, the elephant population increased non-significantly between 2015 and 2022. But elephant populations in the western half of the Angola study area essentially disappeared over that time, while estimated numbers increased in the east, near the Kwando River. Carcass ratios have decreased since 2015 but remain very high at 16%. The growing population estimates are contradicted by the high carcass numbers, suggesting that elephant populations are not healthy in Angola. We suspect that elephants are moving into Angola from iiithe larger populations in Namibia and Botswana but are experiencing high mortality rates in Angola, possibly due to poaching. In Zimbabwe, elephant numbers did not change significantly between 2014 and 2022 in either the Sebungwe or north-west Matabeleland regions. Patterns of change by stratum were generally heterogeneous. Numbers were roughly unchanged over this time in Hwange NP. Two areas just outside the park saw large increases in numbers. Carcass ratios decreased in Zimbabwe since 2014, significantly in Sebungwe and non-significantly in north-west Matabeleland. In Namibia, between 2015 and 2022, the elephant population decreased slightly and nonsignificantly in the Kavango-Zambezi region and increased non-significantly in Khaudum NyaeNyae. Notably, numbers of elephants declined along the Angola and Zambia borders in Kavango-Zambezi. Overall, KAZA’s elephants generally have stable or slowly increasing populations. Rising carcass ratios in some parts of KAZA and the fact that populations are no longer growing rapidly, if at all, mean that continued monitoring of KAZA’s elephant population is critical. Multicountry surveys of KAZA, like the ones in 2014-2015 and 2022, should be conducted regularly to monitor the population and detect any negative changes before they can advance too far. Specifically, high carcass ratios and reports of poaching in Angola and Botswana mean that these populations should be given high priority for future monitoring.
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