Wild Bighorn sheep near a B.C. border town are dying of a disease that's rare in Canada, say conservationists

Vancouver -

A disease caused by the Bluetongue virus is ravaging the wild Bighorn sheep population near a border town in B.C.’s Interior.

According to the Wild Sheep Society of BC, at least 20 Bighorns have been found dead in an area just east of Grand Forks.

Society director Peter Gutsche said the heartbreaking discovery was made about a week and a half ago, after specialists received a notification from GPS tags on some of the sheep that showed they hadn’t moved in many hours.

“We funded the purchase of GPS collars to track Bighorns in that area to assess the herd and the habitat that they live in,” he said.

When the sheep don’t move for more than eight hours, it sets off a “mortality signal.” In this instance, the locals who help track the sheep received numerous mortality signals in a short period.

“They raced down there when they had a number of at least three or four mortality signals go off within a couple hours of each other,” Gutsche said.

Bluetongue is a virus with no specific treatment, and it’s spread by small flies and midges.

Photos from out in the field show the grey, Bighorn sheep lying dead in rocky areas, sometimes on top of each other. Some were found dead next to a fence that had been erected to keep the local sheep population off of the highway.

Lab results found they’d been infected by the Bluetongue virus, which causes high fever and a swelling of the lips of tongues.

The exact number of sheep who’ve died from the disease is not yet known, Gutsche said. Twelve sheep in a population of about 250 are collared with GPS tags. Nine of those 12 sheep have been found dead.

“If we transfer that over to the population of 250, we're looking at potentially a loss of 200 of those animals or so,” Gutsche said. “It could be devastating.”

The hot summer has resulted in a higher population of midges, the insects that spread the virus from one animal to the next.

“The circumstances of the climate this summer, what we've seen here in B.C. … it's caused this to happen, they're seeing similar things with White-tailed deer down in Washington state as well.”

Gutsche said that although the virus commonly circulates among sheep in the U.S., it’s rare in Canada. However, in the past couple of decades, it’s been hitting sheep populations farther north.

”It's found in Australia and Asia and throughout North America – it's not uncommon by any stretch – but up in B.C., it's not something we see.”

For the Bluetongue virus to stop spreading among the Bighorn, we’ll need cold weather, he said.

“At this point all we can really do is wait for a frost. When temperature hits zero those midges that are transferring the disease, they all die. And at that point, the disease – the disease event – is over.”

Anyone in the area who sees the dead animals is asked to leave them alone and warned that the dead carcasses may attract predators to the area.

With files from CTV News Vancouver's Angela Jung