Creating safe passage for wildlife
MISSOULA – Dale Becker can’t believe how many motorists miss seeing the wildlife overpass arcing over U.S. Highway 93 atop Evaro Hill.
“Maybe we camouflaged it a little too well,” the Confederated Salish and Kootenai Tribes’ wildlife manager joked before an aerial survey of the project. And if people don’t notice the big grass-topped “Animal’s Bridge,” they’re not likely to see another 40 underground animal crossings that riddle the roadway in Montana between Evaro and Polson.
And they’re not seeing as many deer, bears, mountain lions or moose in their vehicle headlights.
In 2011, game cameras documented 22,466 animals moving through the passages. That’s up from 12,022 critters in 2010. The tally included 25 species – grizzly bears, river otters, badgers, elk and bobcats among them.
“Over four to six years, we expect to see increasing use,” said Marcel Huijser, a research ecologist from Montana State University who’s gathering data on the crossings. “Animals get accustomed to them and start teaching their young. Then we should start seeing the numbers stabilize.”
This year is the fifth since construction of the full wildlife crossing system finished along a 56-mile stretch of highway.
Huijser still has lots of analysis to finish and a couple of big questions to answer.
How many crossings is enough? Can we show they truly help specific species?
“We have potentially improved wildlife habitat connectivity, and we’ve had a 40 percent reduction in collisions,” Huijser said. “That’s something to be happy about.”
Huijser is still crunching numbers on animal survival rates, especially for grizzly bears. If he can show that a threatened species like the grizzly might have its population directly improved because of the crossings, that would have a huge impact on future projects.
The animal crossings project first approached the highway planning process in the 1990s. It took a decade or so of wrangling, including “a couple of complete stops because of disagreements between governments,” Becker recalled, before the idea gained traction.
The Montana Department of Transportation, Federal Highway Administration and the Flathead Indian Reservation government all had to learn to work together for the project to survive. In addition to creating that working relationship, the parties had to decide what to create.
“We looked at every creek crossing and collision spot,” Becker said. “But we also had to create a concept of the spirit of place, so we could take into account other features and leave the road in a little better condition.”
Highway 93 bisects the prime wildlife habitat of the Mission Mountains and Bob Marshall Wilderness Complex from equally productive public lands to the south, such as the Selway-Bitterroot Wilderness. It jumps the Jocko River, Post Creek and numerous other small waterways that animals use for their highways. The resulting collisions have killed everything from painted turtles to grizzly bears, with hundreds of deer, elk and other animals, along with the occasional motorist.
Huijser’s research found about 29,000 human injuries and 200 deaths a year happened because of highway animal collisions. That works out to an $8 billion annual cost in car repairs, medical care, accident investigations, carcass removal and loss of wildlife.
There were some other examples to build on. Alberta’s Banff National Park has perhaps the most famous set of animal overpasses. Utah has extensive highway fencing networks, while the Florida Everglades experimented with underpasses. In the past 30 years, 13 states including Idaho have added wildlife crossings to their highway systems, providing more data on what animals will and won’t use. States such as Washington have formed policies that require consideration of habitat values and wildlife movement needs in all transportation activities.
Additional work needed to be done on what people might tolerate. For example, the residents of Ravalli, Mont., in a deep and twisty canyon south of the National Bison Range, weren’t happy with the idea of 8-foot-high fences penning them in.
The Ninepipe Wildlife Management Area presented another challenge. Its splattering of pothole lakes and creeks in Montana between St. Ignatius and Ronan were so ecologically complex, the highway designers still haven’t decided how to manage it.
Fencing remains another conundrum. Long, uninterrupted fencing with strategically placed crossings seems like the ideal format. But roads, driveways, railroad tracks and other features break up that boundary. Huijser said the resulting short stretches of fence appear to work only half as well as uninterrupted sections.
“There’s lots of other projects in the U.S. and Canada that are looking at similar issues,” Becker said. “There’s a real art in putting these things on the landscape. It’s getting more and more complicated.”