As Antelope Die-Off Ends, The Mystery Deepens

Nearly half the world’s population of the saiga died in just the past few weeks. Now, scientists are digging in to find out why.

By Vicki Croke

FAO:Sergei Khomenko saiga

Steffen Zuther, acting director of the Association for the biodiversity of Kazakhstan, was among the first witnesses on the scene. Photo: FAO/Sergei Khomenko.

The dying may be over but the accounting has just begun.

More than a hundred thousand antelope have perished in one area in just a few weeks and scientists are left with no idea—yet—of what caused it or why it has extinguished itself.

That’s the strange and deadly mystery playing out right now in Kazakhstan among the herds of a critically endangered kind of antelope called the saiga. The herd animals have dropped dead in the thousands—at least 127,000 gone, according to the official estimate, since mid-May.

It seems to have stopped as mysteriously and abruptly as it began, leaving perhaps only half the world’s population (about 250,000 last year) of saiga alive.

Steffen Zuther-dead saiga

Steffen Zuther observed the devastation: whole herds lying dead—the carcasses of calves curled up at the bellies of their dead mothers. Photo: Steffen Zuther.

Last month, biologists and conservationists came to the saiga calving areas to see the beginning of life—babies being born by the thousands—but instead, what they witnessed was the end of life—with the carcasses of tens of thousands strewn over the terrain. Steffen Zuther, acting director of the Association for the Conservation of Biodiversity of Kazakhstan, was among the first witnesses on the scene. On May 10 and 11 and in the days that followed, he observed the devastation: whole herds lying dead—the carcasses of calves curled up at the bellies of their dead mothers.

In a Skype interview from Astana, Kazakhstan, Zuther told me about the start of this die-off. Within two days of his arrival in the field, he says, “most of the calving herd was dead.”

The catastrophic collapse was reported in New Scientist:

The animals began dying from an unidentified cause around 10 May. The death toll soared within days to 27,000, at which point the Kazakh government requested help from the secretariat of the convention [UN Convention on Migratory Species.]. A team of vets, led by Richard Kock of the Royal Veterinary College in Hatfield, UK, flew out on Friday.

“It’s very dramatic and traumatic, with 100 per cent mortality,” Kock told New Scientist from Betpak-Dala in central Kazakhstan. “I know of no example in history with this level of mortality, killing all the animals and all the calves.” The animals die through severe diarrhoea and difficulty breathing.

Zuther says the die-off has essentially ended, but the race is on to find the cause. Scientists are on scene, conducting necropsies, or animal autopsies, and analyzing tissue. Though they think two kinds of bacteria (pasteurella and clostridia) have contributed to the deaths, they don’t believe they are the main culprits. That’s because these kinds of bacteria are usually present in healthy saiga as well. Most likely, that means something is affecting the immune system and allowing the bacteria to turn deadly…

READ MORE ON WBUR’S THE WILD LIFE

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