Agencies on both sides of the Canada-U.S. border are working to help bighorn sheep after learning about the spread of a devastating disease this year.
In an “early warning note” from B.C.’s Ministry of Forests to government officials, it was reported that psoroptes mange has now been found in the eastern Okanagan Valley bighorn sheep.
It was first discovered in the Okanagan in 2011 near Keremeos.
The disease, caused by mites along with a pneumonia infection (M. Ovi), is blamed in part for as much as a 60 per cent decline in the population.
The Washington State Fish and Wildlife Agency found psoroptes in 2023 in sheep populations known to travel between the U.S. and east Okanagan.
Prior to that discovery, there had been no documented cases in those herds.
Bighorn populations have largely been separated east/west across the Okanagan through urban sprawl, high fences and large lakes.
“Wildlife staff anticipate this outbreak may create additional challenges for an already stressed, culturally and economically significant species,” Shellie Saunders, executive administrative assistant for the Ministry of Forests South Area, wrote in the report.
The infestation doesn’t kill the animals directly, but is believed to weaken them and make them more susceptible to other health issues.
“It’s a disease that definitely hurts their body condition and can inhibit their ability to hear predators and traffic,” said Okanagan Nation Alliance (ONA) biologist Mackenzie Clarke, who has been working on the problem.
“These (east Valley) populations are already under very stressful conditions and then to add this disease is very bad.
“I think right now we need to work on a new strategy. There’s a new version of the drug to treat the disease, but it will be very labour-intensive, so we’re going to have to make sure it’s 100 per cent effective.”
Since the discovery, First Nations, government and non-government agencies have been working together to combat the problem.
That included a 2017 trial program by the Penticton Indian Band where animals were caught and kept in pens while being treated. It had some success.
“So that’s potentially the approach we’re going to take again,” said Chris Barker, vice president of the Wild Sheep Society of BC, one of the lead conservation groups in the matter.
“There has been some progression in the science around treating psoroptes and what we’re hoping to do is another trial. And if it works, then we have a plan in place where we could possibly treat all the populations on both sides of the valley.
“For these animals, it’s just something else they’re dealing with, but if we can get ahead of it a little bit, maybe we can get to a positive outcome and re-establish populations to better keep those sheep populations in the Okanagan.”
South of the border, in addition to the Washington Fish and Wildlife Agency, the society is working with the Colville Confederated Tribes and the Washington Wild Sheep Society.
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