Earlier this summer, conservationists found themselves at a loss in the face of an alarming phenomenon: More than 350 elephants had collapsed and died in Botswana, and no one had any idea why. “This is a mass die-off,” one prominent conservationist said in describing the trend to The Guardian — which, in the months since, has only worsened. Elephants are now starting to die off in Zimbabwe as well.
But according to The Guardian, researchers have begun to narrow down the possible causes.
The first is a neurotoxin in algal blooms, which would help explain why 70 percent of elephants in Botswana died near water holes, where algal blooms have been growing rapidly due to global warming and farming methods. While researchers initially ruled out bacterial toxins, as other species that frequent water holes weren’t dying at the same rate, professor Christine Gosden at the University of Liverpool believes the neurotoxin BMAA (beta-Methylamino-L-alanine) is the culprit: Not only do elephants have a proclivity for playing in water, but their long trunks also have a significant number of olfactory receptors. Also, many of the deceased elephants reportedly wandered around in circles before dying, appearing completely disoriented, which is characteristic of BMAA.
The other theory is a rodent virus called encephalomyocarditis, EMC for short, which elephants could’ve contracted from eating grass or nearby farming crops that were covered in rodent feces and urine. While the virus most commonly affects captive elephants, the virus caused a similar trend in the early ’90s, when 64 elephants died in Kruger National Park.
However, both theories have been met with skepticism. Some researchers doubt that the concentration of BMAA would be high enough in water holes to kill an elephant, and instead theorize that BMAA may be a “contributing factor.” In addition, the Botswana government has eliminated EMC as a possible cause because the heart tissue of the deceased elephants did not show any expected abnormalities.
Meanwhile, the remaining surviving elephants are retreating from the affected areas — an “understandable” response, Dr. Niall McCann, the director of conservation at U.K.-based charity National Park Rescue, told the The Guardian. He continued: “I’m sure you or I would flee if all our friends and relatives were dying, and that’s what the elephants appear to have done.”