Within 100 years it’s quite likely there will be no rattlesnakes in the White Lake Basin and possibly most of the South Okanagan.
Dr. Karl Larsen, a wildlife researcher at Thompson Rivers University, is heading up research on rattlesnake mortality rates in the White Lake area, about 15 kilometres south of Penticton. After a large number of rattlesnakes were noticed by locals dead on the road a research study was launched about four years ago.
The study is delving into the impacts of vehicular traffic on the 1,200 to 2,000 rattlesnakes that call the area home.
“When it’s bison or elephants in the area people will slow down because they’re afraid of the damage. Even moose they say, ‘oh, I don’t want to hit a moose. I might die.’ But with snakes you wouldn’t feel anything,” he said, adding. “I’d say between 400 to 500 snakes are getting killed each year. We will lose snakes here (White Lake Basin) as we have probably have lost the snakes in other places in the Okanagan if we don’t find something to mitigate it.”
Compounding the population problems is that female snakes mature at five to seven years old, and only have pups every third year and when they do produce offspring it’s in usually in small numbers of between two to three or for some larger females up to eight or 10.
Mitigation efforts were focussed on installing culverts along the road to provide an alternate way for the snakes to cross.
Research now is focussed on assessing populations and seeing if the culverts are working.
“A lot of the snakes along Highway 97 are gone. We have an opportunity to at least try to mitigate the losses in the White Lake Basin somehow. We started working with B.C. Ministry of Transportation and Infrastructure and put in culverts. Culverts are a pretty common tool to try and mitigate any animal mortality. They’ve been used a lot but the effects of them haven’t been studied that well,” he said.
Research this year is also delving into whether or not rattlesnakes stop on roadways when it becomes cool at night because the roads are a heat source.
“We can’t say that snakes seek warmth from pavement because it hasn’t been proven conclusive at this point, but it’s kind of an assumption we’ve had. We’ve put temp recording devices in the road and are monitoring,” he said.
The worst time for vehicular death is the spring and fall because the snakes are coming or going from their dens and crossing the road.
Larsen said although many people might have fear or disdain for rattlesnakes, the reptilia has an important role in the ecosystem.
“(It’s) kind of like an engine. You can take some pieces out, but you might not notice for a while, but something is changing,” he said.
Snakes eat a variety of small mammals from mice to moles to pocket gophers and more and other animals might feed on snakes.
“For predators, there might be bobcats, the odd badger and some birds of prey so they’re (rattlesnakes) are a big part of that hot, grasslands ecosystem.”
The study, now in its fourth year, is an offshoot of a long-running study in Osoyoos started by Dr. Christine Bishop, that looks at the impacts of human development on the health of western rattlesnakes. That research is in its 13th year.
The first few years of White Lake study, TRU graduate student Stephanie Winton got creative about finding snakes and tracking those that die by vehicle and other means.
She first spent time tracking down the dens in the area where anywhere from three snakes to hundreds might winter so they do not freeze and die.
Larsen said the snakes go back to the same den year-after-year, mostly.
“These dens were probably established over hundreds of years if not longer. If you’re a snake and you know you’ve gone through the winter you think, ‘I know I can get through the winter in this crack in the ground and I know I can’t freeze, so I have to get back there,” he said.
Research also looked at how far the snakes travel from their den when they leave in the spring to hunt and mate. Most snakes spend the warmer months within one to three kilometres of their den. He noted they can travel more than a kilometre in a single day.
“That’s quite impressive when you consider they are not going straight. They are zigzagging through the grasslands to find prey,” he said.
During the first few years, Winton walked up and down the rural roadway through White Lake Basin each summer. She even spent nights walking and looking along the ditches and in the vast grassland looking for dead rattlesnakes.
“Stephanie Winton not only looked at how many dead snakes were out on the road but also the disappearance rate due to scavengers. She put cameras out as well. The math is elaborate but it comes out that probably the snakes we are counting on the roads only represent 40 per cent of what is actually being killed, so it’s a more serious problem than anyone thought.”
He anticipates it will take less than 100 years before the rattlesnakes are extinct in the White Lake Basin.
“When you are on the backroads, try to pay attention to things that look like old fan belts, or bungee cords. Those are snakes and they need your help.”