August 3, 2013
More Bears Are Now Using Banff Highway Crossings
Susan Bowen for redOrbit.com - Your Universe Online
Anywhere that cars and wildlife occupy the same area, the potential for dangerous interactions between the two exists. Additionally, a highway that prevents large animals from crossing successfully to other parts of their range can seriously disrupt wildlife habitat.
There are 25 wildlife crossing structures in the park; two are overpasses and the rest are bridges or culverts. The overpasses are wide and covered with enough vegetation to resemble the surrounding forest. These work in conjunction with high fencing installed along the roadways. The fencing itself "has reduced wildlife-vehicle collisions by more than 80% and, for elk and deer alone by more than 96%," according to the Parks Canada website.
Study participant Tony Clevenger, an Alberta-based wildlife biologist, explains the purpose of the research. "This is a landmark study because it's the first time anyone has done extensive genetic sampling to address unanswered questions about the use of highway crossings by bears. We knew that bears used the crossings, we just didn't know how many, what percentage of each species' population uses them, whether there is a preference by males or females to use crossings, and if there was a gender or species preference for overpasses or underpasses."
In the course of their three year study, Clevenger and his fellow researchers Mike Sawaya and Steven Kalinowski, both of Montana State University, proved that the structures are doing their job of allowing animals to safely use all parts of their habitat. This is particularly important for the threatened Alberta grizzly bear population.
The researchers set out non-invasive hair snags to provide material for genetic testing. They recovered snagged hair from 20 crossings strung with barbed wire, 420 baited hair traps and 497 rub trees with wires attached. They were able to collect 10,000 hair samples. The team identified 15 individual grizzly bears and 17 individual black bears, meaning that 20 percent of Banff's bears used the crossings. They have also determined that bears are able to use the crossing structures to find mates on the other side.
Sawaya said that their research shows that there is sufficient connectivity to maintain a healthy ecosystem for bears and other large mammals. Clevenger explained that the study's findings are a breakthrough. "This is confirmation of what our previous investigations have suggested but couldn't confirm. We were pretty certain that the numbers of bears using the crossings had steadily increased. Now we know."
Parks Canada adds, "There is a 'learning curve' for animals to begin using wildlife crossings after construction. For wary animals like grizzly bears and wolves, it may take up to five years before they feel secure using newly built crossings. Elk were the first large species to use the crossings, even using some while they were under construction!"
In all, eleven species of large mammals have been recorded using wildlife crossings more than 143,000 times since 1996. This includes grizzly and black bears, wolves, coyotes, cougars, moose, elk, deer, bighorn sheep, and more recently, wolverine and lynx.
The study showed that grizzly bears, elk, moose and deer prefer wildlife crossings that are high, wide and short in length, including overpasses. Black bears and cougars seem to prefer long, low and narrow crossings.
The Banff example is being copied in other places. The Montana Department of Transportation has installed more than 40 wildlife crossings where US Highway 83 passes through prime grizzly habitat on the Flathead Indian Reservation. The Western Transportation Institute (WTI) is studying these crossings to access their success in improving habitat. Rob Ament, manager of WTI's Road Ecology Program said that the research in Banff and Flathead is fundamental to providing solutions to transportation in the rural west, where wildlife-vehicle collisions are common. He concludes, "Between Banff and the U.S. 93 project, we're talking about the two largest wildlife mitigation projects for highways in North America, if not the world. The lessons we learn will be shared with transportation practitioners not only here in the United States but also with those around the globe."