The critically endangered saiga antelope, which once numbered in the millions across Europe and Asia, has undergone a sudden mass die-off that has decreased their population by more than fifty percent.
Previously, the unique-looking saiga had been considered a major conservation success, after rebounding from all-time-low population numbers in the early 1990s. Despite excessive hunting and three previous die-off events, it seemed the saiga were on an upswing.
The most recent die-off is a significant blow to recovery efforts, dropping the population from 250,000 to a mere 120,000. The event coincided with the saiga’s calving season, and primarily impacted female antelope and subsequently their newborn calves. Affected individuals appeared to demonstrate respiratory problems and extreme depression, resulting in a loss of appetite and, within days, death.
Although the exact cause isn’t certain, the die-off occurred more rapidly than a transmissible disease will typically spread. The symptoms more resemble pasteurellosis — a bacterial infection that’s caused by the common gut microbe pasteurella. Both pasteurella and another bacterium, clostridia, were found in every deceased saiga studied by investigators.
These bacteria, though naturally occurring in the digestive and respiratory systems of saiga antelope, could be responsible for the die-off if the antelopes had a weakened immune system. Unusual changes to the climate or to the antelopes’ diets could be responsible for an immunodeficiency that may have resulted in the deaths, though investigations remain inconclusive.
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