There is still mystery about the unprecedented deaths of hundreds of elephants in Botswana in the past two months.
Dr Niall McCann, from the British non-profit organization National Park Rescue, confirmed that his colleagues in the southern African country have spotted more than 350 elephant carcasses in the Okavango Delta since the beginning of May.
Nobody knows why the animals die, and laboratory results on samples will take weeks, according to the Botswana government.
Botswana is home to a third of Africa's elephant population.

McCann told the BBC that his colleagues alerted the local government in early May after a reconnaissance flight. "They saw 169 carcasses in three hours," he said. "An incredible circumstance.
A month later, a new reconnaissance flight led to the identification of another 187 carcasses, doctors made another flight and identified 187 new carcasses, bringing the total to over 350. The deaths from identical causes have already been confirmed. they would instead be 280.
"This is totally unprecedented in terms of the number of elephants dying in a single unrelated drought event," he added.
Why are hundreds of elephants dying?
In May, the Botswana government ruled out poaching as a reason. What is the cause, then, of this massacre? There are other signs that indicate something other than poaching.
"If it were a poison used by poachers, we would see elephants die in larger areas," says the doctor. The presence of natural anthrax, the cause (to a lesser extent, about 100 specimens) of another extermination last year, is also to be excluded.

For the rest, no one can yet rule out poisoning of some kind, or a widespread disease. The way many animals seem to die (they fall forward, face down) indicates something that may have attacked their neurological systems. Before dying, some walk in a circle for hours.
Elephants in Botswana: analysis needed
It is essential to identify the causes of these deaths. Without knowing the exact reason it is impossible to rule out the possibility that a problem also threatens the human population. Especially if the cause lay in water sources or soil.
However, Dr. McCann also puts forward another terrible hypothesis: the pandemic Covid-19, he says, appears to have started in animals, and also in these Botswana elephants. A disaster for nature, but with the potential to be a public health crisis across the African country.