Earlier this year, about 60,000 saigas, a critically endangered, steppe-dwelling antelope, died en masse in central Kazakhstan within the very short span of four days. Geoecologist Steffen Zuther and his colleagues, who were sent originally to monitor the calving of the saigas, immediately got word of other similar population crashes across the country. By early June, the mass dying is over.
Die-offs do happen at times, though this year's population crash was studied by researchers and veterinarians who managed to be on the scene as the mass die-off unfolded. Despite die-offs being not at all unique among animal species like saigas, the extent and speed unto which the events transpired were quite extraordinary, reports The Examiner.
"The extent of this die-off, and the speed it had, by spreading throughout the whole calving herd and killing all the animals, this has not been observed for any other species," Zuther said.
Field workers were able to take samples from the saigas' environment, including the water that the animals drank and the vegetation that they fed on. The researchers also conducted necropsies of the animals. They also observed the behavior of the animals as they died, according to NBC News.
Females of the herd and the young were hit the hardest in the die-off, suggesting that whatever was killing the saigas was being transmitted through the mother's milk. Other tests revealed that toxins, produced by Pasteurella and possibly Clostridia bacteria, which causes internal bleeding, were found in the bodies of the animals.
However, the toxins are commonly found in saigas, and it does not usually harm them unless their immune system is compromised.
Another suggestion by the Zuther and his colleagues state that the shifts in the environment may have also played a significant factor in the die-off, with a cold winter being followed by a wet spring. Such circumstances foster the spread of bacteria. However, such a spread of bacteria is not unusual, either.
The search for answers in the mysterious, mass die-off continues.
