What could have caused 350 elephants to die in Botswana?
University of Pretoria veterinary experts help probe mass loss of life in the Okavango Panhandle: was it pathogen, poison or a perfect storm?
Veterinary scientists from South Africa and Pakistan have pooled their expertise in an effort to understand why more than 350 elephants in Botswana have died in just two months.
A research team comprising Prof Rudi van Aarde and Prof Armanda Bastos of the University of Pretoria’s Department of Zoology and Entomology, Dr Roy Bengis, retired chief state veterinarian of the Kruger National Park, and Assistant Professor Dr ShahanAzeem of the University of Veterinary and Animal Sciences in Lahore, Pakistan has been working to find the cause to ensure such a die-off does not affect other populations in Africa and Asia.
Their commentary – “Mass die-off of African elephants in Botswana: pathogen, poison or a perfect storm?” – was published in the African Journal of Wildlife Research, and calls for further research to identify possible causes of the Botswana die-off.
Elephant carcasses were found in the Okavango Panhandle region - the main watercourse supplying the Okavango Delta - with reports that they could be attributed to a naturally occurring toxin.
The team has not been directly involved in the research into the deaths, with samples being tested by other scientists in Zimbabwe, the US and at UP’s Faculty of Veterinary Science.
“The die-off in Botswana has broader implications because elephant populations are heterogenous – some countries have many, whereas others have very few, and will not withstand the loss of so many animals,” said Azeem.
“Without definite answers around the cause of these deaths, it is not clear whether mitigation is necessary or possible in Botswana, and it will not be possible to prevent future mass deaths.”
Botswana has an estimated 130 000 elephants but Prof Van Aarde cautions that there is a risk of localised elephant extinction if a die-off of similar scale were to occur elsewhere. The elephant population in the Kruger National Park is about 20 000, while there are about 600 elephants in Addo Elephant National Park in the Eastern Cape.
“A die-off of similar scale could be devastating for Addo, so it’s necessary that the cause of the Botswana die-off is identified so conservationists are better prepared,” Bastos said.
In the paper, the team observes that the death of the elephants in Botswana “was indiscriminate in line with their age and gender, while death for some had been sudden as elephants were found collapsed forward on to their chests, tusks in the ground, rather than on their sides”.
What distinguishes these deaths from past mortalities is that they occurred in an area inhabited by elephants, humans and livestock, rather than in a protected area, leading to initial speculation that direct human action was the cause.
However, elephant carcasses were found with tusks intact and no other species were affected, making malicious poisoning and poaching unlikely. This led to suggestions that disease, environmental bio-intoxication or starvation could be to blame.
All of this was considered by the researchers in their commentary, together with indirect human effects specific to the Seronga area. This area is artificially high in elephant densities due to fencing, and crops that concentrate elephants and rodents to the same area.
They point out that anthrax infection has been ruled out as cause of death, as clinical signs consistent with anthrax poisoning were not present and carcasses of other species were not found during the outbreak. Starvation was also an unlikely cause as northern Botswana experienced late heavy rains and bumper crops.
The team is calling for thorough and speedy epidemiological studies to explore disease transmission dynamics in local environmental settings, along with in-depth laboratory investigation to find answers and implement preventative measures.
The team recommends that government and non-governmental organisations assist in investigating the deaths by working with local communities to find fresh carcasses for sampling and “to assist with sampling of possible reservoirs of infection, such as rodents and mosquitoes”.