Saiga antelopes have been roaming Central Asia since the time of the woolly mammoth, an achievement only a resilient species could pull off. But now, "total extinction" may be on the horizon. That's according to researchers studying the deaths of more than 200,000 endangered saigas in Kazakhstan in 2015. Scientists were dumbfounded to see nearly two-thirds of the global saiga population wiped out in a few weeks and raced to discover the cause, reports Gizmodo. They now think they've found it: In a study in Science Advances, lead author Richard Kock says 10 days of high heat and humidity preceding the deaths fatally altered a usually harmless bacteria in the animals' bodies. Kock tells NPR that Pasteurella multocida type B in the animals' tonsils would've been "quite close to the environment of the air," which caused the bacteria "to start growing."
From there, the bacteria entered the bloodstream, causing a disease known as hemorrhagic septicemia. "It's so toxic and so devastating that the animal doesn't show a lot of pathology actually," Kock says. "Suddenly they'd start looking a little bit unhappy and stop feeding. Within about three hours they were dead." Only 30,000 saigas in Kazakhstan survived, likely because they were outside the area of high heat and humidity. But they might not be so lucky if such an event occurs again, a "very, very likely" scenario given that mass die-offs of saigas also occurred in 1981 and 1988, Kock says, per the BBC. Fellow researcher Steffen Zuther says little can be done to prevent die-offs linked to weather as the planet warms. This shows the importance of maintaining large saiga populations and combating poaching and other threats, he says. (Maine's mussels are dying, too.)