COVID-15 DUMMIES - 60,000 antelopes died in 4 days - and no one knows why

It started in late May.

When geoecologist Steffen Zuther and his colleagues arrived in 
central Kazakhstan to monitor the calving of one herd of saigas, 
a critically endangered, steppe-dwelling antelope, veterinarians 
in the area had already reported dead animals on the ground.

"But since there happened to be die-offs of limited extent 
during the last years, at first we were not really alarmed," 
Zuther, the international coordinator of the Altyn Dala 
Conservation Initiative, told Live Science.

But within four days, the entire herd — 60,000 saiga — had died. 
As veterinarians and conservationists tried to stem the die-off, 
they also got word of similar population crashes in other herds 
across Kazakhstan. By early June, the mass dying was over. [See 
Images of the Saiga Mass Die-Off]

Now, the researchers have found clues as to how more than half 
of the country's herd, counted at 257,000 as of 2014, died so 
rapidly. Bacteria clearly played a role in the saigas' demise. 
But exactly how these normally harmless microbes could take such 
a toll is still a mystery, Zuther said.

"The extent of this die-off, and the speed it had, by spreading 
throughout the whole calving herd and killing all the animals, 
this has not been observed for any other species," Zuther said. 
"It's really unheard of."

Crucial steppe players

Saigas play a critical role in the ecosystem of the arid 
grassland steppe, where the cold winters prevent fallen plant 
material from decomposing; the grazing of the dog-size, Gonzo-
nosed antelopes helps to break down that organic matter, 
recycling nutrients in the ecosystem and preventing wildfires 
fueled by too much leaf litter on the ground. The animals also 
provide tasty meals for the predators of the steppe, Zuther 
said. [Images: Ancient Beasts of the Arctic]

"Where you find saiga, we recognize also that the other species 
are much more abundant," Zuther told Live Science.

Saigas, which are listed as critically endangered by the 
International Union for the Conservation of Nature, live in a 
few herds in Kazakhstan, one small herd in Russia and a herd in 
Mongolia. The herds congregate with other herds during the cold 
winters, as well as when they migrate to other parts of 
Kazakhstan, during the fall and spring. The herds split up to 
calve their young during the late spring and early summer. The 
die-off started during the calving period.

Die-offs of saigas, including one that felled 12,000 of the 
stately creatures last year, have occurred frequently in recent 
years. But the large expanse of the country affected by last 
year's die-off meant veterinarians couldn't get to the animals 
until long after their deaths. The delay hindered any 
determination of a cause of death, and researchers eventually 
speculated that an abundance of greenery caused digestion 
problems, which led to bacterial overgrowth in the animals' guts.

Detailed analysis

This time, field workers were already on the ground, so they 
were able to take detailed samples of the saigas' environment — 
the rocks the animals walked on and the soil they crossed — as 
well as the water the animals drank and the vegetation they ate 
in the months and weeks leading up to the die-off. The 
scientists also took samples of the ticks and other insects that 
feed on saiga, hoping to find some triggering cause.

The researchers additionally conducted high-quality necropsies 
of the animals, and even observed the behavior of some of the 
animals as they died. The females, which cluster together to 
calve their young, were hit the hardest. They died first, 
followed by their calves, which were still too young to eat any 
vegetation. That sequence suggested that whatever was killing 
off the animals was being transmitted through the mothers' milk, 
Zuther said.

Tissue samples revealed that toxins, produced by Pasteurella and 
possibly Clostridia bacteria, caused extensive bleeding in most 
of the animals' organs. But Pasteurella is found normally in the 
bodies of ruminants like the saigas, and it usually doesn't 
cause harm unless the animals have weakened immune systems.

Genetic analysis so far has only deepened the mystery, as the 
bacteria found were the garden-variety, disease-causing type.

"There is nothing so special about it. The question is why it 
developed so rapidly and spread to all the animals," Zuther said.

Mystery endures

A similar mass die-off of 400,000 saigas occurred in 1988, and 
veterinarians reported similar symptoms. But because that die-
off occurred during Soviet times, researchers simply listed 
Pasteurellosis, the disease caused by Pasteurella, as the cause 
and performed no other investigation, Zuther added.

So far, the only possible environmental cause was that there was 
a cold, hard winter followed by a wet spring, with lots of lush 
vegetation and standing water on the ground that could enable 
bacteria to spread more easily, Zuther said. That by itself 
doesn't seem so unusual, though, he said.

Another possibility is that such flash crashes are inevitable 
responses to some natural variations in the environment, he 
said. Zuther said he and his colleagues plan to continue their 
search for a cause of the die-off.

https://www.foxnews.com/science/60000-antelopes-died-in-4-days-
and-no-one-knows-why