A Wet and Warm Spring, Then 200,000 Dead Saigas

By STEPH YIN JAN. 17, 2018

A field of dead saigas in Kazakhstan in May 2015. The die-off of the endangered antelopes was found to be caused by bacteria that somehow became harmful after particularly warm and wet weather. Credit Association for the Conservation of Biodiversity, Kazakhstan, Biosafety Institute, Gvardeskiy RK, Royal Veterinary College, London, UK

Among saiga antelopes, the month of May ought to be about new life. But in 2015, it was just the opposite for the Betpak-Dala saiga population in central Kazakhstan.

In only three weeks, about 220,000 of the critically endangered antelopes, most of them newborns and mothers that had gathered to calve, dropped dead across an area the size of Britain.

In a study published today in Science Advances, researchers presented a preliminary account of the cause of the mysterious die-off: Bacteria called Pasteurella multocida, which seem normally to exist harmlessly in saigas’ tonsils, somehow invaded their guts, poisoning their blood and breaking down their organs, leading to death within a few hours…