Fort Smith (May 01/06) - Over the past two weeks, hundreds of people have made the trek south from Fort Smith to see red-sided garter snakes emerge from their winter dens.

Anthony Vermillion, 6, holds a red-sided garter snake in Wood Buffalo National Park on April 23. - Paul Bickford/NNSL photo

"It's an annual event for everyone," said Richard Zaidan, a warden with Wood Buffalo National Park. "They want to come out and see the snakes."

Zaidan said the snakes are one of the biggest attractions in the park.

Fort Smith resident Lorraine Tordiff said she visits the park almost every spring to see the snakes.

"I think they're just amazing," she said.

Tordiff is impressed they can survive in their dens in the dead of winter when everything else is frozen over.

"I think it's unique for the area," she added. "That we would have them so far north."

The snakes hibernate in two underground dens near the Salt River, just inside the park boundary about 24 km south of Fort Smith.

It is the most northerly large concentration of snakes in the world.

Park warden Mike Vassal noted there are several other much smaller populations - up to 50 snakes each -- along Highway 5 and at Salt Mountain. This year, the park is conducting a count of the snakes south of Fort Smith.

The final population estimate won't be known for a couple of weeks.

However, Zaidan said the population appears stable from the last count five years ago. "We're hoping it will be around 700."

Depending on the weather, the snakes enter the dens in late September or early October.

The temperature in the dens -- known as a hibernaculum -- never drops below 2-4C.

They emerge from underground in mid-April, and spend two to three weeks mating. They congregate in mating balls, consisting of as many as 30 males to one female.

"Then they're gone," Zaidan says.

The snakes - which can measure up to a metre in length -- make their way to a small pond about four kilometres to the north. From there, they disperse up to 12 km from their winter dens.

Zaidan noted the snakes turn around in August and head back to the dens for winter.