NATIONAL

Why snakes never get to the other side

KATE LUNAU September 1 2008
NATIONAL

Why snakes never get to the other side

KATE LUNAU September 1 2008

Why snakes never get to the other side

KATE LUNAU

Why did the snake cross the road? It sounds like a bad joke, but for University of Calgary graduate student Adam Martinson, it’s deadly serious. Road fatality is a major hazard to snakes worldwide, he explains; and so, with a team of researchers at Alberta’s Dinosaur Provincial Park, he’s looking at how and why snakes cross the road, in hopes of saving them from becoming roadkill.

Martinson, 24, traps snakes around the park—bull snakes and prairie rattlesnakes both live on the grounds—and releases them onto a test road, either gravel or paved (venomous rattlers have a tube fitted over their head so they don’t bite). Non-venomous bull snakes cross fairly quickly; rattlesnakes, which tend to ambush their prey, are slower and more deliberate (snake crossings take anywhere from one to 10 minutes on, he says). Body temperature seems to be an important factor: some snakes hang out on the warm pavement before making a move. And rattlers seem to prefer gravel, where they can “get a good grip,” Martinson says.

When a car’s bearing down, a snake’s survival instinct kicks in—and that’s the problem. Instead of rushing away from danger, they

stop moving; camouflage is typically their first line of defence against predators, Martinson notes. Some even start rattling to scare off the threat. Theses tactics have worked for millions of years, but they’re less effective against oncoming traffic. Park staff find squashed snakes several times a week. (For the snakes’ protection, this study doesn’t involve moving vehicles.)

No good population counts exist for Alberta’s bull snakes and prairie rattlesnakes, although the province believes the rattler maybe at risk. That makes preventing roadkill all the more important, Martinson says: “Even though they’re not cute and cuddly, they have a place in this world just like everybody else.” Nl