On Aug. 25, 2021, twenty bighorn sheep were found dead outside of Grand Forks, British Columbia, and by Aug. 30, another ten deceased sheep had been located. Mortalities have mounted since then, and a herd once over 150 strong is now in peril. The culprit? A virus seldom seen in B.C. called bluetongue.
Small flies, called midges, transmit the disease to ungulates— sheep, goats, cows, deer, elk, and moose — of both domestic and wild varieties. Symptoms of the disease include deoxygenation, fevers, foot lesions and mortality. It is found worldwide and vaccines are available in many other countries for cattle and domestic sheep.
The virus is not native to B.C. or Canada, though it’s believed infected midges have blown in from the US previously, due to diseased cattle. Bluetongue had been kept away from British Columbia as it requires temperatures of 13 – 35 C to multiply. This means the virus will die off unless it arrives in late summer or early fall.
With increased temperatures forecast in the province due to climate change, the potential for bluetongue outbreaks also increases. This isn’t to say BC will see years of 30+ C temperatures but rather that infected midges will have longer time periods of favourable weather in which to travel and multiply here. Global warming will not only lead to increased rates of infection but also distribution of the virus further north.
Meanwhile, on Vancouver Island, another ungulate disease has been wreaking havoc on black-tailed deer populations. First occurring in B.C. in October of last year, adenovirus hemorrhagic disease (AHD) is suspected in the deaths of hundreds of deer.
AHD was first discovered in California in 1993 and has been steadily traveling up the west coast since then. In contrast to bluetongue, it is spread through the air or direct contact between animals. It can cause difficulty breathing, drooling, seizures, and mortality. Thankfully, like bluetongue, it does not affect people or pets. Further, AHD is also more prolific in the late summer and early fall when temperatures are consistently warm.
While the more visually immediate effects of climate change garner the most attention, it is important that we, and those in the halls of power, pay attention to the myriad of ways it will impact our wildlife and ecosystems. New and new-to-our-region viruses are coming, and we can manage our populations proactively to halt their advances.
Locally that means making sure our ungulate herds are being managed for health and genetic diversity so that if viruses infect a herd, some of the population will have some resistance. To accomplish this, we will need to increase connectivity between natural areas so that disparate herds can breed. It is imperative we act quickly though, as some of the viruses of our warmer future are already here.
Makenzie Konwick is a second year student in the Recreation, Fish, and Wildlife program at Selkirk College.