Nearly half of the world's population of the saiga - a species of antelope older than the mammoth - were wiped out by a freak pathogen last year, in an event scientists are blaming on rapid temperature fluctuations caused by climate change.

More than 200,000 of the saiga, a small antelope native to central Asia, died over the course of two weeks in Kazakhstan's Betpak-Dala region in May, pushing the critically endangered species to the brink of extinction.

In the run-up to this year's breeding season, scientists say that toxins - produced by an otherwise common bacteria that lives harmlessly in the respiratory tract of the saiga - may have been responsible for the sudden deaths.

They say unusual weather - an exceptionally cold winter followed by a very wet spring - may have caused toxins produced by the Pasteurella bacteria to cause fatal internal bleeding in the animals' organs.

"Climate may have had a role to play in this," Richard Kock, a professor at the Royal Veterinary College in London, told Al Jazeera.

"This disease has been associated with domestic animals when there has been a storm or sudden drop of temperature," he added.

According to the researchers, female saigas and their calves were hit the hardest. Within hours of showing symptoms, which included diarrhoea and frothing at the mouth, the animals died.

Millions of saiga, easily recognisable by their distinctive big noses, once roamed the grasslands of Asia, but since the end of the 20th century, poaching has driven the species to the brink of extinction.

Prized for their horns which are used in traditional Chinese medicine, the global population of the saiga has declined by more than 95 percent in the past 15 years, the Saiga Conservation Alliance says.

In 2013, the population of saiga stood at more than 300,000. Since last year's spate of deaths, there are now fewer than 100,000 saiga in existence.