Mystery of African elephants dropping dead unraveled by scientists

Now that the source of the mystery mass mortality of African elephants has been identified, scientists writing a new paper suggest that conditions brought on by the current climate crisis may make outbreaks more likely to occur.

Between late August and November 2020, thirty-five African elephants in northwest Zimbabwe died under mysterious circumstances. Within twenty-four hours, eleven of the animals in the enormous herd perished.

They passed away in front of a tiny window. That’s among the puzzle’s most mysterious pieces. Many creatures pass away in such a short period of time, yet not directly next to one another. According to Dr. Chris Foggin, a veterinarian at Victoria Falls Wildlife Trust in Zimbabwe and coauthor of the study on the cause of the deaths, “it’s really to my mind, rather unique, certainly in this part of the world.”

About 350 elephants in nearby northern Botswana had also perished unexpectedly over the course of three months earlier that year.

At first, officials and specialists couldn’t figure out why the largest population of elephants in Africa was experiencing die-offs. Drought, poisoning, and poaching were all attributed.

Based on samples from 15 of the animals that died in Zimbabwe, the investigation discovered that the elephants were killed by a bacterial infection.

Research that was published on October 25 in the journal Nature Communications revealed indications of blood poisoning, or septicemia, caused by an infection by a little-known bacterium known as Bisgaard taxon 45.

The elephants had to go farther in search of water and forage during the dry season, which resulted in a decrease in food and water supplies.

The area’s high population density, heat, and drought, according to the scientists, were probably contributing factors to the outbreak.

Furthermore, the harsh conditions that experts predict will arise more frequently as the Earth heats may result in an increase in the number of elephant deaths in the future.

Although it’s too soon to conclude that climate change has affected this, Foggin stated that it might in the future if we experience more frequent and severe droughts, see changes in rainfall patterns, and experience a much harsher dry season. “I do believe that there is a greater chance of this kind of mortality event happening again if that is the case.”

The study pointed out that while cyanobacterial neurotoxins have been linked to elephant deaths in Botswana, more information has not been made public. According to Foggin, there is no concrete evidence linking the elephant deaths in Botswana and Zimbabwe.

An embattled species under threat

The flagship species, the African elephant, is severely threatened by habitat loss and poaching. According to the study, the population, which was listed as endangered on the Red List of the International Union for Conservation of Nature, declined by 144,000 to roughly 350,000 between 2007 and 2014. The population is predicted to continue declining at a rate of 8% annually.

Situated almost 90% within Botswana and Zimbabwe, the Kavango–Zambezi Transfrontier Conservation Area covers 500,000 square kilometers (193,051 square miles) and is home to over 227,900 elephants.

The study authors said that evidence of infection was detected in six of the fifteen samples and that this finding was supported by thorough genetic analysis and laboratory isolation of the bacterium.

There was no sign of any viral infection or toxins, including those produced by cyanobacteria.

Delays resulted in poor sample quality

Furthermore, as would be expected with cyanide or other deliberate poisoning, no dead scavengers or other animal species were reported or spotted in the area of deceased elephants, the study concluded.

The study said that even while there was insufficient molecular or cultural evidence to link Bisgaard taxon 45 to more than six deaths in Zimbabwe, the elephants under examination had good physical condition and were not expected to have perished from severe dehydration or malnutrition brought on by the drought.

There were no poached elephants with their tusks removed, and there were no outward indications of stress. According to Foggin, anthrax tests came out negative as well.

The reason for their inability to find the germs in the other samples, according to the researchers, was poor sample quality and a delay in obtaining the required permissions, which meant certain lab work could not be done in time.

The majority of carcasses were in poor condition when they were first sampled, which resulted in low sample quality. Furthermore, getting many approvals from various organizations is necessary for shipping wildlife samples for analysis, a process that can take months, according to the report.

What is known about the bacterium?

Prior research has linked human bite wounds from tigers and lions to Bisgaard taxon 45. A healthy captive parrot and a chipmunk have also been confirmed to harbor the germs.

The unnamed microbe shares close ties with the more widely distributed Pasteurella multocida bacteria, which also causes hemorrhagic septicemia in other mammals, including Asian elephants.

The study also found that the bacterium was responsible for the widespread extinction of 200,000 severely endangered saiga antelope in Kazakhstan in 2015.

According to Foggin, scientists have been keeping an eye on the local wildlife for the bacterium, but since 2020, there have been no verified cases of elephant fatalities linked to Bisgaard taxon 45.

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