Grizzlies using highway crossings

Grizzly bears are using wildlife structures to cross the deadly Trans-Canada Highway in Banff National Park more and more each year.

Researchers with the Banff Wildlife Crossings Project say use of the structures is on an upward trend, increasing every year since monitoring began more than 12 years ago, from five crossings in 1996 to 177 last summer.

They believe about a dozen of the park’s estimated 60 or so grizzlies are becoming more and more comfortable negotiating the crossing structures as the years go by.

“What’s remarkable is that there’s no letup or dips or declines, just a nice straight and steep line upward,” said Tony Clevenger, the project’s principal researcher and a wildlife biologist with WTI-Montana State University’s road ecology program.

The first phases of twinning and fencing the Trans-Canada Highway include 24 wildlife crossing structures, including 22 underpasses and two 50-metre wide overpasses.

Long-term research suggests the animals experience a learning curve, meaning they need to find the crossing structures and feel secure before using them regularly.

Clevenger said there are several factors that likely explain the cause behind the increase in use by grizzly bears, noting a number of bears are likely learning these crossings provide safe passage across the highway.

As well, he said, many family groups have been documented using the crossing structures and young bears are learning to use the crossings when part of a family group, as adults are teaching their young ones.

“When these subadult bears disperse from the maternal range, they continue to use the crossing structures, as they are familiar and comfortable with them,” said Clevenger.

The Banff Wildlife Crossings Project, currently funded by Parks Canada, Western Transportation Institute-Montana State University and private conservation foundations, is now in its 13th year of long-term research.

In 2004 and 2005, a non-invasive technique was pilot-tested for obtaining DNA from the bears using the wildlife crossings. With DNA obtained from an animal’s hair, researchers can create the equivalent of a genetic fingerprint. The unique DNA allows scientists to identify each individual and determine its sex and ancestry.

In 2006, researchers embarked on a full-fledged genetics study with PhD  work by Mike Sawaya, a wildlife biologist at Montana State University, collecting bear hair snagged on wire at crossing structures.

While DNA data from 2008 has not yet been finalized, researchers say they detected about a dozen  individual grizzly bears using the crossings in each of 2006 and 2007.

More than 10,000 DNA samples have been collected from both black and grizzly bears in Banff.

Clevenger said this is a huge bear genetics database with spatially- explicit data that has shown the crossings provide not only sufficient movement of individuals across the highway, but that there is equal movement by males and females.

“Either way you look at these grizzly bear data at the Banff crossings, it’s definitely good news as this is the function we expect of wildlife crossings,” he said.

“I think more remarkable still is not only the amount of crossings by grizzly bears, but movement between sexes,” he added.

“These data from Banff suggest that the 24 crossing structures are functional from a genetic as well as demographic standpoint.”

Clevenger said that grizzly bears do not use all the crossings equally, but have preferences for certain crossings and designs.

He said research has shown grizzlies prefer large, open structures, not just the overpasses, but also open-span underpass structures.

“Given the fact that there are a variety of crossing structure types in the Bow Valley to meet the needs of all wildlife – some prefer the smaller, more constricted crossings – we’d expect to find unequally distributed use of the crossings by grizzly bears,” he said.

“It’s doubtful that this has any effect on grizzly bear population genetics or demographics because the source population is sufficiently large on both sides of the Trans-Canada Highway.”

Clevenger said there are also some interesting results coming out of early monitoring of the new wildlife crossings on Phase IIIB of highway twinning near Lake Louise.

He said they are currently monitoring five new wildlife crossings between Moraine Creek and west of the Highway 93N interchange.

“We’ve detected grizzly bears using one of the large span underpasses twice, along with wolves and moose five times each,” he said.

“At another bridge underpass, we’ve already seen two lynx crossings. This is all just within a few months starting this fall.”

The Association for Mountain Parks Protection and Enjoyment (AMPPE) says the results are promising.

“My understanding is this is a relatively stable grizzly bear population and the actions on the part of Parks Canada with crossing structures and the rest seems to be keeping it in a healthy state,” said Richard Leavens, the group’s executive director.

“AMPPE supports what Parks Canada has done. It clearly is working, which is great.”

That said, Leavens said there are concerns about what would happen when grizzly bears are attracted in the coming years to prime habitat in neighbouring Kootenay National Park as a result of the 2003 forest fires there.

“If bears go over there and we get females who stay there and have their offspring, that’s great, but we’ll have to do something about the highway,” he said.

Defenders of Wildlife Canada say the results of Clevenger’s project and use of the wildlife crossings by grizzlies is very encouraging
“The efforts on the Trans-Canada Highway are a world-renowned example of how to address wildlife conservation,” said Jim Pissot, the group’s executive director.

“The negative component of that is: in two years we will have built about 200 kilometres of fence and probably provide less than five to 10-km of width of crossings. That’s a small fraction of what used to be available.”

Pissot praised the federal government for putting enough funding into completing the wildlife mitigation work for the twinning of the highway.

“The bottom line is this is a very good success to date and our work here is being modeled and studied by highway and wildlife people around the world,” he said.

“The disappointing news is neither the governments of Alberta or B.C. seems interested in following Parks Canada’s lead.”