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Elephants are dying in droves in Botswana. Scientists do not know why

The killings of African elephants have erupted once again in Botswana. In the first three months of 2021 alone, 39 succumbed.

The mysterious deaths occurred at the Moremi Game Reserve in the northern part of the country, almost 100 kilometers from a region of the Okavango Delta, where some 350 African elephants died during May and June 2020. Bewildered scientists have called for thorough investigations as the government sends mixed messages about the cause of death.

Anthrax and bacterial infections had been ruled out in the new deaths and "laboratory tests continue," Botswana's Department of Wildlife and National Parks said in a March 24 statement.

However, the 39 recent deaths have been linked, based on preliminary results, to the same cyanobacterial toxins responsible for last year's mass death, Philda Kereng, Minister of Environment, Natural Resources Conservation and Tourism of Botswana, said in a televised speech state of March 30th. .

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Remote detection of areas of death last year supports the cyanobacteria theory. From March to July 2020, the abundance of cyanobacteria continuously increased as water sources were declining, as reported by researchers online on May 28 in Innovation. With climate change, water masses heat up and toxic cyanobacteria thrive.

Other evidence also points to a pathogen. “The elephant deaths of 2021 are again specific to elephants, as was the case in 2020,” says Shahan Azeem, a veterinary scientist at the University of Veterinary and Animal Sciences in Lahore, Pakistan.

If anthrax was to blame, other animals would be affected, but no. And there would be telltale signs of bleeding in the canals, which was not the case. Poaching was also ruled out, because the bodies of the elephants were intact with their fangs. An investigation into the 2020 largest extinction suggests a pathogen may have been the cause, Azeem and colleagues reported online on August 5, 2020 in the African Journal of Wildlife Research.

Botswana and neighboring countries in southern Africa have a cross-border conservation agreement under which elephants can cross borders during migration. While Botswana, home to some 130,000 African elephants, has struggled to explain the recent deaths, Zimbabwe on its eastern border has reported the deaths of 37 elephants in 2020. Sudden deaths in one area worry others. Scientists had blamed Zimbabwe's deaths for the first time for haemorrhagic sepsis, a disease caused by the bacterium Pasteurella multocida.

But more recent genetic studies point to a related bacterium, Bisgaard Taxon 45, as the culprit, says Jessica Dawson, CEO of Victoria Falls Wildlife Trust in Zimbabwe, who has been doing lab tests for that country’s death.

In March, the International Union for Conservation of Nature called African forest elephants "critically endangered" and African savannah elephants "endangered." IUCN lists poaching as the main threat along with a rapid increase in human land use, which has diminished and fragmented elephant living areas.

Habitat reduction and climate change may play a role in keeping elephants exposed to the deadly pathogen, whatever that is, the researchers say. The area is a hot spot for human-elephant conflict. Fencing to keep animals away from crops and the deep Okavango River had “imprisoned” elephants, Duke University biologist Stuart Pimm and colleagues wrote on Jan. 11 in PeerJ. Investigators tracked elephants in the area and showed very limited movement.

“What is clear is that in Botswana and, indeed, elsewhere, fences restrict such movements,” says Pimm. "Elephants can't escape what can be a dangerous situation for them."

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