Delays in testing could “literally kill elephants,” added Hiley.
Dr Mmadi Reuben, senior veterinarian in the Botswana Department of Wildlife and National Parks, said the government was taking the deaths seriously and had responded “promptly, adequately and responsibly – as soon as we receive this information”.
He said that some tests ruled out common causes like anthrax, which is caused by bacteria that occur naturally in the soil. He and his colleagues are now working with laboratories in Zimbabwe, South Africa and Canada to perform other tests. “It will not be a single thing where we will say, ‘We have sent samples, now we are done,’ said Dr Reuben. “It’s an ongoing dialogue with different laboratories.”
There is still no evidence that the dead are a criminal act on the part of humans, he added.
Cyanide, which poachers sometimes use to poison elephants, seems unlikely, as carcasses tend to congregate near where the poison was deployed. It also tends to kill other animals, but no other species seems to be affected in this case. However, it is possible that other poisons can be used against elephants, and Mr. Hiley says that some of them can dissipate quickly.
Covid-19, he added, is unlikely because the disease has not yet infected residents of remote communities in Okavango. There is also no evidence that elephants can contract the virus.
Dr. Thouless suspects that a natural illness is the most likely culprit. One of the main candidates is encephalomyocarditis, a viral infection that can be transmitted by rodents, which can cause neurological symptoms. He killed around 60 elephants in Kruger National Park in South Africa in the mid-1990s. Botswana also recently emerged from a drought, which could have left some elephants stressed and more vulnerable to disease, said Dr Thouless .
At this point, he continued, the deaths are not a conservation crisis, as the figures documented so far represent only a small percentage of the 15,000 to 20,000 elephants that live in the Okhandango Panhandle. “It is painful, but it is currently insignificant in terms of population,” he said.
Past examples also show that when conditions are favorable, elephants can quickly rebound. For example, in 1970 and 1971, a drought in Tsavo East National Park in Kenya killed around 5,900 of the park’s 35,000 elephants. In 1973, the population had returned to 35,000.