Officials in Botswana are investigating the unexplained deaths of hundreds of elephants in the country in recent months in what has been described as a "conservation disaster".
More than 350 elephants carcasses have been spotted in the southern African country's Okavango Delta since the start of May.
A cluster of elephant deaths was first reported in the region in early May, with 169 individuals dead by the end of the month.
By mid June, the number had more than doubled, with the majority of the elephants found dead clustered around waterholes.
Elephants of all ages and both sexes have been dying, according to local reports.
The cause of the deaths is not yet known, with laboratory results on samples taken from the animals still weeks away from being ready, according to the government.
The two main possibilities are thought to be poisoning or an unknown pathogen. Covid-19 has also been mentioned as a possible cause.
Dr Niall McCann, the director of conservation at UK-based charity National Park Rescue, described the developments as "mass die-off on a level that hasn’t been seen in a very, very long time".
“There is no precedent for this being a natural phenomenon but without proper testing, it will never be known,” Dr McCann told The Guardian.
The way the animals appear to be dying, with many appearing to have dropped on their faces, and reported sightings of other elephants walking around in circles suggests something could be an indication of neurological impairment, he added.
Some 15,000 elephants live in the Okavango Delta, accounting for roughly 10 per cent of Botswana's total elephant population.
The animals and eco-tourism more widely account for a huge part of Botswana's GDP, which means their deaths could pose an economic crisis as well as a conservation one.
“You see elephants as assets of the country. They are the diamonds wandering around the Okavango delta,” Dr McCann said.
“It’s a conservation disaster – it speaks of a country that is failing to protect its most valuable resource.”
There have been no reports of a surge in elephant deaths in neighbouring countries in recent weeks.
Dr Cyril Taolo, acting director for Botswana's department of wildlife and national parks, told The Guardian local officials had so far confirmed at least 280 elephants had died, and were in the process of confirming the rest.
"We have sent [samples] off for testing and we are expecting the results over the next couple of weeks or so," he said.
"The Covid-19 restrictions have not helped in the transportation of samples in the region and around the world.
We’re now beginning to emerge from that and that is why we are now in a position to send the samples to other laboratories.”
