Study looks to save rattlers from Canadian roads

Todd Korol, Yahoo News 12 Aug 08;

In this arid river valley in southeastern Alberta, Adam Martinson is trying to find out why rattlesnakes cross the road.

Martinson, a University of Calgary student working on a Masters degree has come to Dinosaur Provincial Park, listed as a United Nations World Heritage site, to study why snakes slither onto -- and too frequently die on -- the asphalt blacktop of the region's roads.

"Road mortality is a significant factor of influencing snake populations around the world," Martinson said. "In southern Alberta it's particularly important because the snakes aren't moving very fast across the roads and there is a huge amount of development."

Snakes are pressured by both oil and gas exploration in the Western Canadian province's semi-desert southeast, but also by residential development in the booming region.

For prairie rattlesnakes, considered to be potentially a "species at risk" by the Alberta government, and bull snakes, their nonvenomous cousins, roads are a deadly hazard.

The snakes move onto roads looking for safety, food, mates and the heat absorbed by the asphalt. However, when a vehicle approaches the snakes don't move.

They coil themselves up in a defensive posture and the rattlers shake their tails to warn off the danger.

It's a strategy that has served them well for millions of years but is of little use in fending off a truck.

"It happens almost every day," Martinson said.

One South Carolina study found that more than 80 percent of timber rattlesnakes that tried to cross roads traveled by 2,000 or more vehicles a day were killed.

"We're trying to learn ... how we can design roads and plan for roadways that are going to have less of an impact on snakes," he said.

Part of Martinson's study includes trying to get a firmer handle on just how many bull and rattlesnakes there are in southern Alberta. Both species are considered "data deficient" by wildlife conservation agencies, meaning that no one really knows how many of the reptiles live in the region.

The snakes are a key to the area's ecosystem, keeping a check on rodent populations. They are also prey for other creatures.

For his study, Martinson traps snakes within the park and releases them onto a control road, where he tracks how fast they move across the surface and at what angle.

He'll use the data to create a model to predict the probability of a snake being killed based on traffic density.

But here, just before the prairie descends to meet the Red Deer River, an area famous for striking badlands geography and its rich beds of dinosaur fossils, it's clear what the risks are for the reptiles.

Stretched out on the asphalt, partially flattened is a prairie rattler nearly three feet (one meter) long. A conservation officer stops his truck, scoops up the dead serpent and throws it into the vehicle's bed. It's another statistic for Martinson's study.

(Writing by Scott Haggett; editing by Rob Wilson)