Okanagan rattlesnakes 100 years away from being extinct, biologist says

Thompson Rivers University researcher says action is needed to protect vulnerable species.

Thompson Rivers University researcher says action is needed to protect vulnerable species

Rattlesnake populations in B.C.'s Interior could collapse over the next 100 years, according to researchers at Thomson Rivers University. (Karl Larsen)

Rattlesnake populations in B.C.'s Interior are at risk of extinction if measures aren't taken to curb population decline, according to a Kamloops research biologist.

The venomous snake population in the south and central Okanagan is dwindling and could collapse entirely over the next 100 years, says professor Karl Larsen.

"They're really taking it on the chin — they're getting bombarded from different directions," he told CBC Radio One's Daybreak South.

"The rattlesnakes that we have in south central B.C. are really pushing the limits of being a rattlesnake," he said. "We like to pride ourselves in having these beautiful warm summers — [but] we're still in Canada, we're still pretty far north."

There are between 1,500 to 2,500 rattlesnakes in the south Okangan, according to Larsen's research. He says B.C.'s sourthern Interior is the northern limit of where rattlesnakes can survive in the hemisphere.

"Even before you put people in the equation, there are natural forces at work preventing rattlesnakes from extending their range further — and temperature is a big one," he said.

But human interactions with the snakes can be far deadlier than cold temperatures.

Human forces

Researchers believe hundreds of snakes in the region are killed each year by motor vehicles and other interactions with humans.

"You start lumping on other pressures — development, people, loss of habitat, and roads are becoming an increasingly significant issue," he said. "We all like to drive, and we don't really spot those snakes sitting on the road."

Karl Larsen is a professor of wildlife ecology and management in the department of Natural Resource Sciences at Thompson Rivers University. (Jenifer Norwell/CBC)

The federal and provincial governments have identified B.C.'s rattlesnake population as being at risk.

The province has outlined a recovery strategy which includes reducing road mortality and preserving habitat. Culverts have been installed in some problem areas in an attempt to give the snakes a safe passageway across busy roads.

Larsen says work is now being done to determine how effective mitigation efforts have been.

"Land managers have worked very hard to keep rattlesnakes on the landscape — but as we dig deeper into their ecology, we're seeing [these efforts might not be helping]," he said. "There's just ramifications of having a lot of people on the landscape."

Female snakes generally only reproduce every three years. And while healthy snakes may give birth to up to 12 snakes, smaller ones might only have a litter of three, Larsen says.

"It's getting harder and harder to find healthy denning populations of rattlesnakes, anywhere near the central Okanagan."

With files from CBC's Daybreak South

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