Kazakhstan's endangered saiga antelopes have began dying en masse since mid-May, and scientists have not been able to find the exact cause yet.
According to government data, almost 120,000 of these unique and ancient animals have died so far and experts are worried for their future.
Already under the protection, most of saiga antelopes live in steep Kazakh lands — 200,000 out of a total population of 260,000 — and the recent deaths represent the biggest decline of the animals in recent history.
One of Central Asia's most symbolic animals, the saiga antelope has distinctive bulging eyes, large noses and spiraled horns. They were listed as Critically Endangered in 2002 by the International Union for Conservation of Nature (IUCN).
Experts are trying to find out the cause of the mass deaths, and from a presence of bacteria to environmental reasons, there is a long list.
Kazakh officials say the carcasses bear no wounds or other signs of trauma, and suspect of a natural bacteria that is carried in animals’ mouths and nasal passages. But they also pointed out that this bacteria kills only weak animals, so there must be a reason for their weakened immune system.
Currently more than 500 people are working to figure out the cause and to prevent more deaths as four large herds have already died-off completely.
"A 100 percent mortality for the herds affected is extraordinary," professor Richard Kock from the Royal Veterinary College in London told AFP.
The number of saiga antelopes diminished from one million to 250,000 in twenty years, and scientists believe it will take a decade for the population to recover from the latest deaths.