An unknown disease or infection has ripped through Kazakhstan’s critically endangered saiga antelopes over the past few weeks, killing 120,000 animals—nearly half of the world population.

The total number of saiga is estimated at 260,000, about 200,000 of which lived in Kazakhstan.

“We have lost almost half the global population of saiga antelopes, which is a serious blow for the ecology of the steppe and conservation efforts,” said Aline Kühl-Stenzel, a terrestrial species officer covering saiga for the Convention on the Conservation of Migratory Species of Wild Animals. “The large majority of animals affected are adult females and calves, so this will severely limit the reproductive capacity of the population.”

Saiga were nearly eliminated after the fall of the Soviet Union, when rampant poaching for meat and for the antelopes’ unique, curved horns—which are used in traditional Asian medicine—caused the population to drop from 1 million to just 81,000. Legal protections and intense conservation efforts have managed to boost the population over the past few years, although poaching remains a major problem.

(Photo: Courtesy Kazakhstan Ministry of Agriculture)

Previous mass saiga losses occurred in 2010, 2011, and 2012, although fewer than 15,000 antelopes died over the three years. The Kazakh government has previously attributed those deaths to a bacterial infection called pasteurellosis, although E.J. Milner-Gulland, chair of the Saiga Conservation Alliance, said this was never conclusively proven.

The cause of this year’s deaths also remains a mystery. Milner-Gulland said it is most likely an infectious agent, perhaps a disease the antelopes picked up from livestock. Samples are currently being studied to try to identify any diseases or other factors responsible for the deaths.

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“This year, we are better prepared, and I am confident that the in-country and international experts will be able to make a diagnosis in due course,” she said.

Whatever is killing the animals, it appears to be 100 percent fatal. Symptoms include diarrhea and foaming from the mouth. Most, if not all, of the deaths have been young saiga and females that have recently given birth. Saiga engage in a grouping behavior where females gather together in vast herds to give birth to calves all at once. At least one of these birth sites has been completely wiped out by the disease, reported Kühl-Stenzel.

Will the saiga be able to recover from this terrible death toll?

Saiga do reproduce quite rapidly when their populations are safe. “Females born in May are already able to mate in December and generally have one calf in the first year,” said Kühl-Stenzel. “In their second year, they often have twins.”

Even with that level of fecundity, she said, “it will for sure take many years for the population to bounce back, especially in the light of severe poaching and continued strong demand for saiga horn in Southeast Asia.”

Saiga have existed on the steppes and deserts of Kazakhstan since before the last ice age, when they mingled with mammoths and wooly rhinos. As historical survivors, Kühl-Stenzel expects they will eventually recover, although this year’s mass mortality will be felt for some time.

“The current die-off is a severe blow for steppe and desert ecology, as well as for local people who often see saiga as a symbol representing their traditional nomadic roots,” she said.

According to Milner-Gulland, the next steps to protect the saiga will depend on the diagnosis. For example, if the disease is found to have come from livestock, vaccination efforts could be needed.

“We can also step up protection activities,” she said. “With the population so small, any further losses from poaching could be very damaging.”

Kühl-Stenzel said the presence of nongovernmental organizations and experts on the ground, along with Kazakhstan’s newly established protected conservation areas, “will have to be part of the solution in the future.”

Both experts praised the magnificence of these rare antelopes. “They are the most beautiful creatures to watch,” said Milner-Gulland. “They stream across the steppe in a graceful ribbon. The birth areas are magical too. Standing in the middle of remote steppe with their strange mooing all around you and the feathergrass blowing in the wind is a great privilege.”

This year, though, those same magical birthing areas are mostly silent, except for the sound of hundreds of people burying the bodies of thousands of dead saiga. Hopefully, the mooing of birthing mothers will return in the years to come.