It started in late May, colleagues arrived in central Kazakhstan to monitor the calving of one herd of saigas, a critically endangered, steppe-dwelling antelope, veterinarians in the area had already reported dead animals on the ground.
But within four days, the entire herd — 60,000 saiga — had died. As veterinarians and conservationists tried to stem the die-off, they also got word of similar population crashes in other herds across Kazakhstan. By early June, the mass dying was over.