OF THE MIND
TECH INSTRUMENT CENTER
TO BLACK MOUNTAIN
MAY UNLOCK MAD COW DISEASE
SPEECH WASN'T FREE
For wary wildlife used to walking in woods and meandering through meadows, a swath of asphalt presents a formidable barrier. Cars whooshing by can make crossing such an obstacle dangerous for both animal and driver. Automobile collisions with large wildlife kill hundreds of people and cost millions of dollars in damages every year. But a less visible impact, for humans at least, is the mortality of small animals and the fragmentation of their habitat caused by roads.
Montana's rapidly growing Bitterroot Valley is currently upgrading its main transportation artery from a two- to four-lane highway. U.S. High-way 93 bisects the valley, winding its way through wetlands and cutting across streams and riparian areas. Local concerns about the impact of the road expansion on wildlife prompted the Montana Department of Transportation to address the issue. The result was a three-year partnership with a University of Montana biologist and an ingenious culvert design that shows a lot of promise.
Residents who ride their bikes along the path paralleling the highway just south of Lolo aren't surprised that animals might cross the road in culverts. In fact, the bike trail leads safely under the highway through a large culvert. During the expansion of the road from Lolo to Florence, many small culverts — about three or four feet in diameter and 180 feet long — were placed to allow water to flow between seasonal wetlands divided by the road. MDT put shelves along the length of some of these culverts in the hope that animals would use the platforms to cross even when the pipes were half-filled with water.
But while people can be guided to safe passage, how could the road engineers know if animals were using the shelves?
To answer that question, MDT called on UM biology Professor Kerry Foresman, who has spent much of his career looking for rare species in remote locales. He's an expert in remote sensing — which uses tools such as cameras, heat and motion detection systems and tracking plates — to find hard-to-locate animals. The engineers at MDT asked him if he could use his technology to see if the shelves were helping animals get across the road safely.
In an initial pilot study, Foresman found that about the only animals using the shelves were deer mice and house cats, yet he knew the area was home to many species.
To figure out how to improve the wildlife crossings, MDT supplied Foresman with $180,000 for a pilot study and then a three-year grant. His technology would see how animals responded to the culverts, and his knowledge of animal behavior would help him suggest improvements.
Foresman and his full-time research technician, Jeremy Moran, used the project to create a unique research methods class that included 10 of his top students each semester.
They spent a full day each week collecting field data, and applied what they learned about animal behavior to improve the culvert effectiveness.
Foresman and his students placed cameras with heat and motion sensors, set live trap lines in the nearby habitat and took data that recorded everything from automobile traffic patterns to vegetation types around the culvert openings. One of the first things they learned was that most animals had difficulty walking on the relatively large-sized mesh used to build the shelves.
"If you are a prey species and you have to pussyfoot along — you're not going to want to go on the shelf," says Foresman.
"It's like us trying to run along on railroad ties — you're going to face-plant."
Foresman and his team bought black plastic material used as bed liner in pickup trucks and placed sheets along a shelf. Later, they retrieved their film and found proof that more species had used the shelf. However, engineers didn't like the bed liner because it might disrupt water flow when the culverts were filled. Foresman found a compromise suitable for both animal and engineer by using a finer wire mesh small enough that animals could run along comfortably but water could still pass through.
The researchers captured thousands of images of critters such as porcupines, yellow-bellied marmots and skunks using the shelves when the culverts were partially full of water. They photographed a painted turtle plodding safely along while traffic zoomed overhead. Foresman's equipment even caught sight of an elusive fisher crossing westward using the culverts to aid its travel toward the Bitterroot Mountains.
Still, among the many species captured on film using the shelves, there was one they didn't see — an important prey species called a meadow vole. This is a small, timid mammal that lurks in tunnels beneath the matted grass and vegetation. For the shy vole, the biologists theorized, the open space of the shelf was just as threatening as crossing the open road.
In an effort to find a solution for the vole, Foresman went to a building supply store and bought 180 feet of white plastic tubing. His students crawled into the culverts and tied the tubing to the bottom of the shelf. They designed and built plywood ramps to funnel willing voles into the tubes. Since cameras would be useless to document any use of the pipes, they cut flaps open halfway through the passageway and put sheets of upside-down contact paper with soot-covered plates on either side. This way, if an animal walked along, it would get its feet dirty and leave prints on the sticky paper.
The next day they found hundreds of sets of tiny vole tracks left by overnight commuters.
"What we were able to bring to this was an improvement in design backed by real research," Foresman says.
He's optimistic about the results so far. In three years of working on this stretch of road, Foresman has never seen so much as a dead raccoon. But where the safety factors don't exist, he said he sees dead animals.
The research and technology won't stop the impact of roads and increased traffic on wildlife, but it's clear that improveddesigns do seem to help mitigate the fragmentation of habitat and allow many animals to cross an otherwise dangerous or impassible barrier. Roscoe Steel, Foresman and MDT worked together to incorporate the changes in shelf design and the specialized ramps into a product that can be easily retrofitted into existing culverts.
Construction is under way on the next stretch of U.S. Highway 93 between Florence and Hamilton. The new road will have five or six culverts with shelving and a 10-foot dry culvert designed for larger animals to use. There also will be two bridges spanning creeks with paths beneath them for animals and a freestanding bridge that will replace a now filled gully. Foresman plans to set up his detection equipment to research the effectiveness of the bridges and larger culverts and then suggest needed improvements.
Recently, MDT nominated Foresman's research and the improvement of the animal shelf technology for a citation from the American Association of State Highway and Transportation Officials. This group would champion the shelves to the Federal Department of Transportation and to states around the country.
"The Montana Department of Transportation, I think, has taken a lead in looking at wildlife issues," Foresman says.
Foresman is involved in teaching and research on other road projects around the state, including wildlife bridges planned in the Swan Valley and reconstruction of the Thompson River Road — the latter for which he recently was awarded a two-year $435,000 grant.
"In such a rapidly developing area, it's neat to see that so many species still exist," he says.
His work, and that of his students, aims to help keep it that way.