New scientific study into the deaths of Botswana’s Elephants in 2020
Last year over 330 elephants were found dead in the Seronga district of Botswana’s Okavango Delta. These mysterious deaths raised huge concerns all around the world, with rumours of poisoning, poaching and anthrax as being causes. After months of sampling, testing and analysis by laboratories in Zimbabwe, South Africa and the USA, it was announced that the elephants had died from drinking contaminated water from waterholes which contained cyanobacterial toxins, caused by a bloom of cyanobacteria. These are a naturally occurring bacteria, with blooms forming in waterholes under certain climatic conditions.
A new study has just been published into the elephant deaths, exploring the broader ecological implications. It agrees that human poisoning and poaching are unlikely causes, especially as other animals were not affected and all the elephant carcases were found intact, with their tusks.
“Most of the elephant carcasses were found within an area administratively known as NG11, along the Panhandle region of the Delta – a region where human-wildlife conflict is rife. Neither NG11 nor neighbouring NG12 have protected status and are designated for subsistence agriculture. These regions neighbour the Kavango-Zambezi Transfrontier Conservation Area”.
Whilst most of the region is under IUCN status, the Seronga area administrative blocks (NG11, NG12 and part of NG13) have no protected status. They are cut off from the surrounding habitat by the deep waters of the Okavango River and Delta and border and veterinary fences.
The restriction of freshwater supplies had forced elephants to use waterholes that had possibly been naturally polluted by algae blooms, although they suggest there is not enough evidence to confirm this as the main cause, especially as no other animal species were involved, so they suggest contagious disease could be a possible cause.
The area in which the elephants were found is enclosed by fences and a deep channel of water, which confines their movements and dispersal. This is a contributing factor into the local elephant population having a relatively high population growth rate, even though poaching had increased in the years 2014 to 2018.
These deaths only represented about 2% of the area’s elephant population. It is thought that this elephant population are under stress due to human-wildlife conflict in the region. Their confinement, along with a relatively high density of animals, could lead to them being more susceptible to natural diseases and/or toxins due to anthropogenic restrictions.
Confinement and relatively high densities probably explain why the die-off occurred in only one area. Their findings suggest that a re-alignment or removal of fences, that restrict elephant movements and limits year-round access to freshwater, should be part of the longer term conservation plan for the area.
The 2020 elephant die-off in Botswana report was published in January 2021 and is available to read online at PeerJ – Life and Environment.
Main photograph –images from Reuters