Why Did Two-Thirds of These Weird Antelope Suddenly Drop Dead?

It took just three weeks for two-thirds of all the world’s saiga to die. It took much longer to work out why.

The saiga is an endearing antelope, whose bulbous nose gives it the comedic air of a Dr. Seuss character. It typically wanders over large tracts of Central Asian grassland, but every spring, tens of thousands of them gather in the same place to give birth. These calving aggregations should be joyous events, but the gathering in May 2015 became something far more sinister when 200,000 saiga just dropped dead. They did so without warning, over a matter of days, in gathering sites spread across 65,000 square miles—an area the size of Florida. Whatever killed them was thorough and merciless: Across a vast area, every last saiga perished.