- Conservationists were baffled by the mass deaths of the endangered saiga antelopes
- New research has linked the mysterious death to a bacterial infection
(CNN)In just a few days, more than one-third of the world's saiga antelopes died off. No one knew why — until now.
The mysterious death of 200,000 critically endangered antelopes in Kazakhstan last year was caused by a bacterial infection, according to a new report by the Saiga Conservation Alliance (SCA).
Several labs used tissue samples collected from the carcasses during the die-off, and confirmed that the deaths were linked to bacterium Pasteurella multocida. This pathogen caused hemorrhagic septicemia in the saiga population.
The findings are surprising because this bacterial infection, although known to affect animals such as buffalo, cattle and bison, had never been documented to affect an animal group with a 100% mortality rate.
News of the mass deaths emerged in May 2015, after more than 100,000 saigas dropped dead in 10 days.
At the time, mostly female antelopes of the Betpak-Dala population, the largest saiga group at the time, gathered in herds to give birth. Shortly afterward, the groups started showing signs of illness and quickly died, according to SCA.
Thousands of carcasses -- saiga mothers with their calves -- were found in the vast open wilderness of central and western Kazakstan, a U.N. Environmental Program spokesperson told CNN in 2015.
With its distinctive bulbous nose, the saiga antelope is a relic of the Ice Age, once coexisting with now-extinct creatures such as wholly mammoths and saber-tooth tigers thousands of years ago. Although its body may look similar to a deer and its horns resemble an African gazelle's, saigas are evolutionarily distinct from antelopes, according SCA's website.
Their horns and chestnut-colored coat have made them precious game for poachers. After the Soviet Union broke apart in the early 1990s, unregulated hunting hurt the herbivores, according to the World Wildlife Fund's website.
Pressure continued to mount on the population as it competed with humans to maintain its habitat — the saiga antelope is known for its spectacular migration that spans a vast landscape. Now they are one of the fastest declining mammal species on Earth, according to SCA.
Researchers around the world are still working on understanding why the bacteria had such devastating effects on the population.
During the early 1990s, the saiga antelope population was over 1 million, but now it is estimated to be around 50,000, according to the World Wildlife Fund.
In the meantime, the SCA has urged authorities in Kazakhstan to protect the species from hunters and habitat loss.