A recent decline in a California bighorn sheep population in the Ashnola-Similkameen region has raised concerns with the Ministry of Environment, but wildlife officials say it is not unusual.
“Most mountain ungulates are just really sensitive and they’re kind of living on the edge anyways, they’re kind of looking for an excuse to get sick,”said provincial wildlife veterinarian Dr. Helen Schwantje. “It’s mostly issues associated with respiratory disease they have periodic die offs where pneumonia kills them. This is something that has been documented for decades.”
Although so far the reason for the 50 percent drop in the herd numbers in the Snowy Protected Area is unknown it is not believed to be related to interaction with domestic sheep.
“We had a large die-off of Okanagan sheep in the winter of 1999,” said Schwantje. “That one was pretty classic, all ages died and once those die-offs occur you really can’t stop them (you) have to let them ride.”
In that situation it is believed there was a connection between the wild and domestic stocks and government officials worked with local farmers to mitigate the problem by keeping the animals separated.
“We were very lucky because the lamb production returned very quickly and the herds are doing very well now but in some cases it never does,” said the vet.
She believes the current problem in the southern part of the valley actually began well before 2011.
It was also about the same time it was noticed the sheep were exhibiting symptoms of the highly infectious disease called psoroptes or sheep mange. Caused by a tiny mite which usually lives in the ear canal of the animal, Schwantje does not feel it is the cause of the population decline, although it may be a contributing factor, at least to some degree.
She added psoroptes was once a problem with domestic sheep but was eradicated in the 1920s. This time around it is believed to have been spread north by an infected animal from Washington State which came in contact with Canadian sheep.
The disease has now been found in the wild stocks as far north at the Penticton Indian Reserve.
The Ministry of Environment has been closely monitoring the populations since 2010 and has several programs in place to gather more information. That includes ground and aerial surveys, collaring and monitoring individual sheep.
