Wildlife Bridges: Safe Passage at Wildlife-Human Crossroads

By Neva Knott

In my recent post, “Losing Hope,” I gave the analogy of deer encroaching on yards, specifically in the town of Ashland, Oregon, as a way to talk about common sense and living in harmony with nature even when planning human spaces and endeavors.

As populations increase–those of human and other species–and natural resources decrease, co-habitation becomes more of an issue. Human development constantly destroys and fragments non-human habitat. Then what? Where do the animals go? How do they traverse landscapes to find food, water, shelter, and mates?

In the extreme, other species die because of this.

In another version of the extreme, or possibly the common sense to wildlife scenario, non-human species–deer, bear, cougar, coyotes, and wolves, to name the Oregon/Western states usual suspects–come on to territory now considered human, continuing to look for the resources they previously found there. In the case of Oregon’s wolves, this is the rub…ranchers don’t want wolves near livestock, but when wolves are forced out of their native feeding areas or have to travel fragmented landscapes, often crossing open range, they intersect with these human spaces. Though the livestock kill, or depredation, rate is very low, it’s a heated issue and one that governs wolf management.

Deer, bear, cougar, coyotes also make their way onto human landscapes, looking for food and water–because their foraging habitat has been destroyed or replaced with ranches, houses, shopping malls. The saddest example I’ve witnessed was a family of mule deer standing between Wal-Mart and the gym in Redmond, Oregon, train tracks behind them and pretty much surrounded by parking lots.

As these animals, and other species like marmot, field mice, frogs, birds, bats…move around to forage, they need cover for safety. Imagine a field mouse trying to make it across a large lawn with no shrubbery to hide under and with all sorts of predators above. This is the issue with habitat fragmentation.

Roads are one of the biggest threats to wildlife movement. In fact, I’ve heard it said that deer are the most dangerous animal in Oregon because so many of them cause car accidents when crossing roads.

Recently, wildlife managers/agencies in a handful of places have installed wildlife bridges as a way to provide habitat corridors, giving safe passage to our wildlife friends, and even providing habitat as part of their construction.

This video from Conservation Northwest explains the concept and shows construction on the I-90 corridor project in Washington State:

In 2012, Oregon Department of Transportation build the state’s first wildlife underpass along a high-collision stretch of Highway 97, a bit south of Redmond where I saw those poor stranded deer.

us 97 corridor

Aerial view of Highway 97 underpass. Photograph courtesy of ODOT.

Recently, in a follow-up piece in the Oregon Public Broadcasting’s Field Guide the rationale for the project was explained:

“Mule deer west of the Cascades typically migrate between the mountains in the summer and the lower elevation lands in the winter. Highway 97 presents a stark barrier in that journey…When deer need to get where they’re going, they often must conquer an obstacle course of fences and roads. Miles upon miles of human made barriers snake across even the most wide-open landscape.The deadliest obstacles they confront are dangerous, virtual walls of flying metal: highways full of high-speed traffic: ‘You have stranded herds of animals,’ says Kevin Halesworth, a biologist with the Oregon Department of Transportation.  ‘As the traffic level increases, the deer are less able to cross the highway until it gets to a point where from studies, the deer just won’t cross at all any more.'”

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Mule deer using the underpass. Photograph courtesy of ODOT.

The underpass created a connected habitat–or as it is often termed, habitat connectivity, for the mule deer, and created safe passage for both wildlife and motorists along the shared deer migration and Highway 97 corridor.

In a recent project status update published in The Bend Bulletin, state scientists reported an average of 95 deer per year were killed by car collisions before the underpass. Now that animals are using the underpass, the number of car-collision deaths has dropped “drastically.” In the same article, a scientist for Oregon Department of Fish and Wildlife explained, “hundreds of similar projects around the country have shown an 85 percent or better decrease in the number of animal-versus-vehicle collisions.”

Mule deer aren’t the only travelers through the underpass. Cameras track usage. ODOT told Oregon Public Broadcasting bobcat, raccoon, turkey, weasel, badger, coyotes, bears and more use the crossing: “We also had a bobcat that was not only using the structure to cross the highway, he was actively hunting in here and we have pictures of him capturing prey.”

The Highway 97 underpass is Oregon’s first wildlife corridor project. Animal Road Crossing–ARC–an agency dedicated to designing and building wildlife passageways, gave it the Exemplary Ecosystem Initiatives Award in 2012. ODOT is planning a second project along Highway 97, an overpass, which is scheduled for completion when funding is secured.

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Illustration courtesy of ODOT.

Several US states and many places in Canada have installed wildlife bridges. You can see pictures of some of them here in this publication from Oregon Department of Fish and Wildlife and on the website for ARC. The Center for Large Landscape Conservation published a reader-friendly report on the science of and need for wildlife connectivity, citing climate change as a key factor to consider in keeping wildlife habitat intact.

The issue of wildlife corridors is an aspect of defining critical habitat during the land use planning process, one the Western Governors’ Association is taking to task. The Association, in December 2013, launched the “Crucial Habitat Assessment Tool (CHAT), a cooperative effort of 16 Western states to provide the public and industry a high-level overview of “crucial habitat” across the West.”

One of my favorite connectivity projects is Yellowstone to Yukon, an organization with the stated vision of, “An interconnected system of wild lands and waters stretching from Yellowstone to Yukon, harmonizing the needs of people with those of nature.”

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The Y2Y area is outlined in white. Image courtesy of Yellowstone to Yukon.

The organization also calls their project “The Geography of Hope,” in that, “Stretching some 2,000 miles in length (3,218 km), the Yellowstone to Yukon region is one of the last intact mountain ecosystems left on Earth. It is home to the full suite of wildlife species that existed when European explorers first arrived and it is the source of clean, safe drinking water to 15 million North Americans.”

Wildlife bridges are common sense, don’t you think?

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7 thoughts on “Wildlife Bridges: Safe Passage at Wildlife-Human Crossroads

  1. Pingback: Wildlife Bridges: Safe Passage at Wildlife-Human Crossroads | Walking on the Wild(life) Side

  2. Brilliant, wildlife corridors are a great way forward; they’ve already been used to help elephants successfully find new feeding areas and fresh water in Africa.

    I have a new blog post I wonder if you’d be interested in; I’m looking for artists, writers, photographers and more to feature in my blog to write about what they feel are key issues in conservation, focus species etc. Would you be interested in contributing?

    https://cjwaterfieldart.wordpress.com/2015/10/28/the-conservation-conversation/

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