Preliminary analysis indicates that a combination of environmental and biological factors is contributing to this catastrophic event, which has seen four large birthing herds of the critically endangered Saiga antelope wiped out since mid-May this year. Primarily mothers and calves are among the carcasses; not a single animal has survived in the affected herds.
According to information received from the members of the CMS expert mission, it is becoming clear that two secondary opportunistic pathogens, specifically Pasteurella and Clostridia, are contributing to the rapid and wide-spread die-off. However, the hunt for the fundamental drivers behind the mass mortality continues since these bacteria are only lethal to an animal if its immune system is already weakened.
The animals die within hours of showing symptoms, which include depression, diarrhea and frothing at the mouth.
“They get into respiratory problems, they can’t breathe easily. They stop eating and are extremely depressed; the mothers die and then the calves are very distressed and then they die maybe one or two days later,” said Richard Kock from the Royal Veterinary College in London.
While mass mortality events are not unusual for the saiga antelope, they typically affect far smaller numbers of animals, on the order of about 10,000 saigas. The magnitude of this event, therefore, is unprecedented, given the population’s large size.
Steffen Zuther, head of the Association for the Conservation of Biodiversity in Kazakhstan (ACBK), was monitoring calving in one of the herds containing thousands of affected animals.
“Over two days [in the herd I was studying] 80% of the calving population died,” he told the BBC.
The whole herd then died within two weeks.