Tuesday, June 02, 2015

Mystery Disease Strikes Saigas

courtesy: Kazakhstan Ministry of Agriculture
The central Asia steppes antelope, saiga (Saiga tartarica), was once a conservation success story.  Hunted for its horns (superstitious medicinal use) about 95% of the population disappeared and it was declared critically endangered.  After implementation of strict anti-poaching rules, the antelope recovered from 50,000 to 250,000 last year. Now a mysterious disease is sweeping through the herds, killing a third of the world's population. To loose 120,000 individuals of any species in three weeks is phenomenal, say conservation scientists. The carcasses litter the steppes [photo right]; dead saiga are being buried in mass graves scraped out by earth moving equipment.

An international team of wildlife biologists is examining tissue samples to find out what is killing the odd-looking creature that has the body of a deer but the nose of an elephant seal. It is also a remarkable creature. A survivor from the Pleistocene, saiga once inhabited all of the Eurasian continent and North America, from Britain to the Northwest Territories. It was a characteristic animal of Scythia according to Strabo, who called it "Kolos" and described it as drinking through its nose. Males use their inflated, fleshy proboscis [photo left] to attract females with flatulent noises.

It will take weeks to isolate a disease agent from tissue, meanwhile speculation about the cause abounds. Chemical pollution is a often mentioned as a possibility, but previous die offs were thought to be related to lush growth of plant species that make the antelope dangerously bloated [photo right]. In 1988 there was a mass die-off of 434,000 animals. Certain grasses of the Brassicacea family are poisonous to ruminants if eaten in large quantities, causing diarrahea, bloating and foaming fermentation. Brassicacea species proliferate in wet conditions. The steppes are wet this year due to heavy rains. But the speed of infection and 100% mortality is inconsistent with that hypothesis according to an expert on the scene. The animals were infected with Pasteurella and Clostridium, both deadly, but common in healthy animals that have tolerance for these organisms. The United Nations agency overseeing saiga conservation measures says the die-off is over, but long term survival of the species is in doubt if science cannot determine what killed the saigas.