At least 40 vultures have been poisoned in Botswana, the latest victims of a mass poisoning in the country in recent months.

Vultures play a critical role in keeping ecosystems clean of diseases found in rotting carcasses, but in Southern Africa, they are sometimes poisoned deliberately by poachers, or accidentally by farmers.

Pictures posted on Facebook show dozens of mostly white-backed vultures lying dead beside a river or being burned to prevent further poisoning.

Conservation group, Raptors Botswana, said the poisoning was reported by a farmer in the Rakops area, in the centre of the country.

Sources have told Eyewitness News that up to 60 of the critically endangered birds could have been killed in this incident.

Kerri Wolter of South Africa-based conservation group VulPro said many of these vultures would still have been feeding chicks on the nest.

In June last year, more than 530 mostly white-backed vultures were poisoned by poachers in the north-east of the country. It’s not clear whether this latest tragedy was accidental or a deliberate poisoning of the birds.