In May 2015, researchers in central Kazakhstan witnessed something really strange: thousands of saiga antelopes began acting a bit weird, becoming unbalanced, and then just plopping on the ground within a few hours — dead. Over the course of just three weeks, more than 200,000 saigas died, or about 60 percent of the global population.

“I had never seen anything like it,” says Richard Kock, a wildlife veterinarian and professor at the Royal Veterinary College in the UK. “It was very concerning because it was so unnatural, outside of the realm of my experience.”

Dead saiga antelopes in the steppes of Kazakhstan, in 2015.

Photo: courtesy of the Joint saiga health monitoring team in Kazakhstan (Association for the Conservation of Biodiversity, Kazakhstan, Biosafety Institute, Gvardeskiy RK, Royal Veterinary College, London, UK)

The saiga antelopes were later found to be infected with a bacterium that causes blood poisoning and internal bleeding, or hemorrhagic septicemia. Now, a new study shows that unusually wet and hot weather played a key role in causing the outbreak. How exactly that happened, though, remains a bit of a mystery.

Researchers analyzed historical data related to other mass die-offs of saigas from the 1980s, and found that when the outbreaks occurred, it was warmer and more humid than normal, according to a new study published today in Science Advances. That doesn’t bode well for the future of this critically endangered species. A warmer world could make such outbreaks more likely, and if that happens, the saiga antelopes could go extinct.

Saiga antelopes, whose bulbous noses recall the tauntaun creatures in Star Wars, live in the grasslands of central Asia, from Hungary all the way across Mongolia. They’ve been around for thousands of years, since the time of the mammoths, but they’re now at risk of disappearing because of hunting and habitat loss. “Extinctions took out other animals, but the saiga persisted through modern time,” says Kock, one of the authors of the study. With thick furs and unusual noses that warm up cold air before it gets to the lungs, the animals are highly adapted to extreme environments, and being able to survive harsh winters.

A saiga calf.

Photo: courtesy of the Joint saiga health monitoring team in Kazakhstan (Association for the Conservation of Biodiversity, Kazakhstan, Biosafety Institute, Gvardeskiy RK, Royal Veterinary College, London, UK)

In 2015, as the antelopes got together in the spring to give birth, a sudden disease outbreak wiped out an enormous number of saigas in central Kazakhstan, almost 90 percent of the local population. Such die-offs aren’t unheard of when it comes to mammals called ungulates: the Mongolian gazelle, wildebeest, and white-tailed deer have all experienced mass deaths. But what happened in 2015 was unprecedented, says Kock. In affected herds, 100 percent of animals deceased — an insanely high percentage. “If everything dies, the bacteria doesn’t benefit, the host doesn’t benefit. It doesn’t make biological sense,” Kock tells The Verge.

Conservation scientist Eleanor Jane Milner-Gulland, who’s worked with saiga antelopes for 25 years, says the die-off was traumatic for field biologists. She remembers seeing photos of the lifeless animals spread over the steppes of Kazakhstan: “It was horrible,” Milner-Gulland says. The antelopes had succumbed to a bacterium called Pasteurella multocida, which lives in their tonsils. But somehow, the bacteria seemed to have proliferated to a point where the animals got sick and died.

To understand whether environmental factors were to blame, Kock, Milner-Gulland, and their colleagues analyzed troves of historical data on saiga antelopes, including satellite images and weather records. The animals had died en masse before, with symptoms similar to the 2015 event. In 1981, 70,000 saigas went heels up, or about 15 percent of the population in the Kazakh region of Betpak-Dala. In 1988, 270,000 died, or 73 percent of the regional population. The data showed that in the days leading up to all outbreaks, the humidity was higher than usual, over 80 percent, and the average minimum daily temperatures were also higher than normal, particularly in 2015.

Dead saigas.

Photo: courtesy of the Joint saiga health monitoring team in Kazakhstan (Association for the Conservation of Biodiversity, Kazakhstan, Biosafety Institute, Gvardeskiy RK, Royal Veterinary College, London, UK)

How exactly those conditions sparked the outbreak isn’t clear, Kock says. It could be that bacteria spread when it’s hot and wet, but to be sure, more research is needed. It’s also not clear whether climate change can be blamed for the 2015 outbreak, according to Kock. Climate models aren’t precise enough to determine whether changes in climate are affecting weather in a very specific region, but the trend is obviously pointing toward the world becoming a hotter place — and that’s concerning.

Global temperatures have already increased by roughly 1.53 degrees Fahrenheit (0.85 degrees Celsius) since 1880, and saiga antelopes are already being affected, Milner-Gulland tells The Verge. In the last 40 years, the areas where the animals go to give birth have already shifted north. And since there seems to be a connection between weather and the outbreaks, more die-offs are expected in the future, Kock says. “The question is, will it cause extinction?” he says. “I think that’s a risk.”

One way to protect saigas is to make sure their populations are strong and healthy, so that if there is an outbreak, more animals can survive. That means limiting poaching, and giving the antelopes enough space to migrate across the grasslands. But saigas are also “really good at recovering,” Milner-Gulland says, and their populations can bounce back quickly: females can have babies when they’re only one year old, and newborns are large enough that they can run and migrate quickly.

So, for these mythological-looking creatures, there’s hope for survival.