In central Kazakhstan entire herds of saiga antelope lay dead-more than 120,000, or nearly half of the species worldwide. These animals died off within two or three weeks, a shocking pace. This is an unprecedented mass mortality events for saiga antelopes relative to the total population size, and the last case in 2010 saw only 12,000 dead saiga.
"The scale is absolutely unprecedented," says Dr. Aline Kuehl-Stenzel, the terrestrial species coordinator of the Convention on the Conservation of Migratory Species of Wild Animals.
Saiga antelopes are already critically endangered and have been receiving the assistance of various conservation efforts, but this loss is a serious blow. In the last decade saigas were just beginning to bounce back after their global numbers plummeted by 95 percent, dipping below 50,000 animals. The animals die experiencing respiratory difficulty and severe diarrhea.
"I'm flustered looking for words here," says Joel Berger, a senior scientist at the Wildlife Conservation Society. "To lose 120,000 animals in two or three weeks is a phenomenal thing."
After Kazakhstan officials requested assistance from the United Nations (UN) the Secretariat of the Convention on the Conservation of Migratory Species of Wild Animals (CMS) sent researchers to form a working group to investigate. The UN team along with experts from the Food and Agriculture Organization (FAO) and the UK's Royal Veterinary College arrived on site to conduct post-mortem analyses.
As of yet the cause of the mass die off remains a mystery, but scientists suspect a combination of biological and environmental factors are fueling the catastrophe. Mass mortality events often take place during the birth period, because it is easier for pathogens to affect more saiga when vast herds of females congregate to all give birth within the same one week period. Because entire herds, mostly mothers and calves, are left dead, researchers think that what problem causing the deaths is always fatal.
"It is an extraordinary thing to get one hundred percent mortality," says Dr. Richard A. Kock, an expert on wildlife disease at the Royal Veterinary College.
Members of the CMS expert mission say that Clostridia and Pasteurella, secondary opportunistic pathogens, are part of the reason the animals are dying. However, these are only fatal to saiga if they have seriously weakened immune systems. Dr. Kock explains that the time from illness until death was too short for the saiga to have passed on their infections.
"The time period is too short," Kock says. The real question, then, is the underlying "why." It will take weeks for the team to detect any pathogens in the bodies.
Erlan Nysynbaev, Vice Minister of the Ministry of Agriculture of Kazakhstan says that "this loss is a huge blow for saiga conservation in Kazakhstan and in the world, given that 90 percent of the global saiga population is found in our country. It is very painful to witness this mass mortality."
"Authorities in Kazakhstan are responding quickly to this disaster and are working hard to solve the mystery behind this mass saiga die-off" CMS Executive Secretary, Bradnee Chambers says. "I am pleased that the international expert mission we were able to send, at very short notice, is now contributing to these efforts."
Saigas were one of the species who survived the Ice Age, inhabiting a broad swath of the world between what is now Alaska and the UK. Once the climate warmed permanently, the saiga went on to prosper on the steppes of Central Asia. Poachers ran wild in the former Soviet Union as they sought the horns of the saiga, bought principally by those who use traditional Chinese medicines.
Eventually there were five countries that were still home to saiga: Uzbekistan, Turkmenistan, Russia, Mongolia, and Kazakhstan. In 2006 these nations signed a conservation memorandum of understanding and deployed anti-poaching measures. These efforts were the direct cause of the rise in population from 50,000 to 250,000.
"It was a big success story," says Eleanor J. Milner-Gulland, the chair of the Saiga Conservation Alliance.
However, when the Kazakhstan government contacted Dr. Kuehl-Stenzel earlier this month, she received the disturbing news that hundreds of saiga, including many mothers with nursing calves, had suddenly died. The number of dead has risen since that time.
Part of the national monitoring program included the aerial survey that first revealed the mass deaths. Although the saiga have stopped dying-as CPS collars on animals show-it seems that the actual numbers are even higher than reported thus far. In addition, Dr. Kuehl-Stenzel has received more reports of dying saiga.
"The die-off may not be over," Kuehl-Stenzel says. "This is unconfirmed, but it fills us with great fear."
Climate change is another possible causal factor the researchers are investigating. For example. The ecology of the steppes has been disturbed by this year's heavy rainfall, and this may have affected the food supply of the saiga. Heavy chemical pollution from farms and factories is also a serious problem in Central Asia. "There's a lot of history there," said Dr. Kock, who will be examining pollution's possible role in the die-off.
The final answers about environmental factors may not be coming anytime soon. "We have some simple stories, but it's probably more complicated," says Kock. "We have to do the science and let the evidence speak."
Some speculate that rocket fuel from Kazakhstan's rocket program was have poisoned the saiga, but Dr. Kuehl-Stenzel thinks this is unlikely.
"Experts are working around the clock to investigate the impacts in terms of wildlife health of the relatively high rainfall observed this spring, the composition of the vegetation and other potential trigger factors including a suite of viruses. None of the data analyzed to date indicates that rocket fuel is related to the mass die-off. Fresh laboratory results are becoming available every day," says Kuehl-Stenzel.
Even if the die off is over for now, experts are concerned that even more dangerous diseases pose a threat-not to mention the ever-present poaching issue.
"Saiga antelopes often have twins and populations are able to rebound quickly. Our hope is that if we can control what is driving these mass mortality events as well as tackle the number one threat to saigas-wildlife crime and poaching-populations will be able to recover. Collaboration among all stakeholders is vital. Kazakhstan is leading the way and I look forward to the Range States putting in place strong policies at the CMS Saiga meeting," Chambers says.
Whatever the core cause of this particular die off, the fragility of the species is apparent; coordinated efforts will still be crucial to the survival of the saiga antelope.
