Half of world’s rare antelope population died within weeks – ‘I’ve seen some pretty grim things, but this takes the biscuit’

Desdemona Despair

[cf. 60,000 antelopes died in 4 days, and no one knows why and Saiga antelope population declines 95% in 15 years]

By Emma Howard
3 November 2015

(The Guardian) – More than half of the world’s population of an endangered antelope died within two weeks earlier this year, in a phenomenon that scientists are unable to explain.

At least 150,000 adult saiga antelopes were buried during a fortnight in May, but scientists say the actual figure will be significantly higher as many more carcasses were found but not counted as part of the burials. Calves were not counted, but it is thought that hundreds of thousands died too.

Known for their distinctive cylindrical snout, bulging eyes and curled horns as well as their ability to survive dramatic changes in temperature, the animals are one of the most endangered species on the planet. Before the most recent die-off, the estimated population was between 250,000 and 320,000. The die-off has only occurred in the plains of Kazakhstan, where 90% of the global population resides.

The mass mortality defies understanding of how biological systems normally behave, scientists have said. They believe the deaths occurred too quickly to be attributed to a transmissible disease.

There are no wounds or evident trauma that would point to poaching and no obvious signs of malnutrition. Soil and water samples have not revealed any significant presence of toxins or poisoning by radiation, despite claims by Kazakhstan activists that fuel from Russian rockets could be to blame.

The most likely culprit is a bacteria called pasteurella already living in the throat of the animals, Prof Richard Kock from the Royal Veterinary College at the University of London told the Guardian.

Although normally dormant, it is likely that an unidentified trigger caused it to change its character and “become nasty”, he said, producing toxins that could attack the antelope’s organ systems and cause death within hours. [more]

Half of world’s rare antelope population died within weeks

Carl Zimmer
2 November 2015

(The New York Times) – A mysterious die-off of endangered antelopes last spring in Central Asia was even more extensive than originally thought, killing more than half of the entire species in less than a month, scientists have found.

“I’ve worked in wildlife disease all my life, and I thought I’d seen some pretty grim things,” Richard A. Kock, of the Royal Veterinary College in London, said in a telephone interview. “But this takes the biscuit.”

At a scientific meeting last week in Tashkent, Uzbekistan, Dr. Kock and his colleagues reported that they had narrowed down the possible culprits. Climate change and stormy spring weather, they said, may have transformed harmless bacteria carried by the antelopes, called saigas, into lethal pathogens.

It is a scenario that deeply worries scientists. “It’s not going to be something the species can survive,” Dr. Kock said. “If there are weather triggers that are broad enough, you could actually have extinction in one year.” […]

Overhunting reduced their numbers to just 50,000 by the 1990s. Conservation measures had helped saigas rebound to a few hundred thousand individuals scattered across five distinct ranges from Russia to Mongolia.

But in May, Steffen Zuther of the Frankfurt Zoological Society and his colleagues visited the calving grounds of the largest population, called Betpak-dala, in Kazakhstan. They discovered huge numbers of corpses scattered across the steppes.

The deaths tapered off by the end of May, and initial estimates put the death toll at 120,000 saigas.

In June, Mr. Zuther and his colleagues began making aerial observations and counting survivors. They spotted far fewer animals than they had expected. The scientists now estimate that at least 211,000 saigas — 88 percent of the Betpak-dala population and over half of the species — died in May.

“It’s really horrific,” said Aline Kühl-Stenzel, the terrestrial species coordinator of the Convention on the Conservation of Migratory Species of Wild Animals.

Once individual saigas became ill, they typically died within hours. Entire herds were quickly wiped out. “This is really not biologically normal,” Dr. Kock said. [more]

More Than Half of Entire Species of Saigas Gone in Mysterious Die-Off