Botswana on Friday said tests to discover the cause of the deaths of hundreds of elephants in the famed Okavango Delta have been inconclusive, but they did not eliminate poisoning.
The government has established that 281 elephants died, although independent conservationists say more than 350 perished.
The deaths were first flagged by the wildlife conservation charity Elephants Without Borders (EWB), whose confidential report of 356 dead elephants was leaked to the media early in July.
Before dying, several elephants appeared weak, lethargic and emaciated, with some showing signs of disorientation, difficulty in walking or limping, EWB said.
The environmental resources ministry said the tests showed no presence of pesticides that would ordinarily be involved in poisoning.
“Results received so far do not eliminate poisoning. Therefore environmental factors, including naturally occurring toxins, are still being investigated,” the ministry said.
Authorities have so far ruled out poaching, as the tusks were found intact. Tests were being conducted at specialist labs in South Africa, Canada, Zimbabwe and the US.