No one knows what's killing them, but scientists estimate that almost half of the world's saiga (Saiga tatarica) have perished since May 10th. To date, researchers on-the-ground unofficially estimate that 120,000 saiga have died in Kazakhstan from what appears to be a wildly virulent disease, although no cause has been ruled out. Saiga are bizarre-looking, Ice Age antelopes that once roamed Central Asia in the millions, but are now listed as Critically Endangered.