Anthony P. Clevenger  /  Western Transportation Institute
One of two 150-foot-wide wildlife overcrossings in Banff National Park. To see a grizzly bear using it, click "Next" at the bottom of the page.
By Mike Stuckey Senior news editor
updated 7/6/2005 11:43:08 AM ET 2005-07-06T15:43:08

Quick: Why did the grizzly bear cross the road? Yes, just like the chicken in the old joke, he needed to get to the other side. But in these days of 70 mph interstates crammed with two-ton SUVs and semi trucks, biologists and highway planners have a more urgent question: How the heck is Yogi going to get there?

Around the globe, humans are rapidly and radically expanding their efforts to help their wild friends get over and under highways more safely. In the United States, such projects crisscross the map: Washington state to Florida, Massachusetts to Southern California. The furry, feathered and scaled beneficiaries include everything from elk to turtles.

“There is a certain movement out there, and there certainly is money being spent,” says Dr. Jodi Hilty, a landscape ecologist with the Bozeman, Mont.-based Wildlife Conservation Society.

A list of U.S. wildlife-crossings includes increasingly elaborate — and expensive — projects in a number of states:

  • At the top in scope and cost is a 15-mile expansion along Interstate 90 in the heart of the Washington Cascades. Still in the planning stages, one vision for the seven-year project would incorporate 14 animal passageways, adding $113 million to its final cost, potentially accounting for a third of the entire price tag.
  • A 56-mile reconstruction of U.S. Highway 93 currently under way between Evaro and Polson, Mont., on the Flathead Indian reservation includes more than 40 wildlife crossings, adding about $9 million to the $133 million project.
  • Eight alligator underpasses are part of a recently awarded $148 million contract to rebuild 4.5 miles of Highway 1 in the Florida Keys. And Florida, already successful in using crossings to reduce highway deaths of the endangered panthers that roam the Everglades, has now allocated $125,000 to see if a solution can be found to save thousands of turtles from being flattened by cars on U.S. Highway 27 at Lake Jackson near Tallahassee.

The crossing structures range from small culverts beneath a roadway for reptiles to overpasses 100 feet wide or more, planted with trees and other vegetation to match the pieces of the forest they connect. In some cases, creating connections is just a matter of raising and extending bridges that are already crossing streams and rivers to include adjacent pathways.

Despite what appears to be a sudden flurry of activity, “it took a lot of time for it to reach a fever pitch,” says Trisha White, director of the Habitat and Highways Program for Washington, D.C.-based Defenders of Wildlife. “I’ve been working on this issue for five years and I can see a tremendous difference.”

The new field of 'road ecology'
White and others say that difference is owed partly to the emerging discipline of “road ecology” and a growing body of data that shows the crossing structures work, and partly to more federal money aimed at reducing the environmental impacts of road projects.

Dr. Anthony P. Clevenger of Montana State University’s Western Transportation Institute is one of the wildlife-crossing field’s leading researchers. For years, he has studied the use of wildlife crossings and fencing in Canada’s Banff National Park, a 2,500-square-mile wilderness bisected by the Trans-Canada Highway, which boasts “the only large-scale complex of wildlife mitigation passage structures in the world.” Park officials say their “exceptionally diverse” crossing structures and the “world’s longest, year-round monitoring program” put them in a league of their own.

Clevenger’s research has found Banff’s efforts to be “highly effective in reducing wildlife-vehicle collisions,” according to the park’s Web site. “The mitigation measures have resulted in more than an 80 percent reduction in all wildlife road-kills, and more than 95 percent reduction in road-kills for ungulate (hooved) species.”

And while few things tug at human heartstrings like Rocky Raccoon-turned-pancake or Bambi’s battered body in the ditch, “road-kills of large predators and certain reptiles and amphibians can be highly significant” in ecological terms, writes Dr. Richard T.T. Forman of Harvard, a pioneer in the burgeoning field of “road ecology.” Among species like Minnesota wolves, Florida panthers and Spanish lynx, already low in numbers and slow to reproduce, just a few fatal encounters with vehicles can be disastrous for their populations, says Forman.

Larger problem: A disconnect
But highway construction creates larger problems of degraded habitat and “the barrier effect that reduces landscape connectivity,” Forman says. When roads and freeways chop a species’ territory up, they create a host of problems for the animals, who need freedom of movement to find food and mates, escape predators and make seasonal migrations.

The jury is still out on how well wildlife crossings address the overall issue of habitat connectivity and if they are truly cost-effective, although there is positive data. “In spite of these valuable kernels of information, gaping holes in our knowledge of functional wildlife crossing systems remain,” the Banff Web site acknowledges.

Despite the validation that his often-quoted research offers, Clevenger told that a larger factor in the current rush to incorporate wildlife crossings in highway projects is the bottom line.

Beginning in the ’90s, federal highway spending bills earmarked funds for environmental mitigation, Clevenger said. Incorporating wildlife crossings in their highway plans has “basically given the (states) the opportunity to tap into that money. … So that’s really gotten a lot of states thinking about building them and then building them.”

One of those states is Washington, where environmental studies of the I-90 project have yielded three options for wildlife crossings that have now been put out to gather public comment.

When it comes to wildlife crossing projects, “obviously, right now the showcase is Banff,” says Defenders of Wildlife’s White, but “when I look at the plans for Washington, if they go with the best scenario there, it’s going to be the best thing we have in North America.”

The Highway 93 project in Montana deserves a nod for “the most progressive … in terms of the number of miles and the number of crossings,” says Hilty of the Wildlife Conservation Society.

But Washington, with a range of $20 million to $113 million, is the big bucks entry in the current crossing sweepstakes. I-90 project engineer Randy Giles acknowledges that, under some scenarios, the cost of providing the 14 animal passageways in the Cascades could account for more than a third of the tab for the whole project, expected to run from $311 million to $728 million.

Is that expense a gamble, given the uncertainty over how well the crossings provide connectivity, a “controversial issue” squarely addressed in environmental planning documents for the project?

“We know that we can connect habitats,” says Giles. “What’s hard to do is quantify them and say, ‘Well, triple the amount of elk crossed at this place.’

“I wouldn’t say it’s a dice-roll.”

Anthony P. Clevenger  /  Western Transportation Institute
A grizzly bear crosses one of the Banff overpasses.
Environmentalists are quick to agree.

Charlie Raines, the director of the I-90 Wildlife Bridges Coalition, an umbrella group formed to push for the “highest standard” of wildlife passages across the revamped mountain freeway, points out that it runs like a belt over the 35-mile waist that joins Washington’s North and South Cascades. “This is the place they’ve got to move through,” he says of the elk, deer, foxes and other species that call Snoqualmie Pass home. Widened to six lanes, the interstate is “going to be impassable for most species” without crossing structures.

Raines and Giles also consider the I-90 project a good example of a new spirit of cooperation between traditional foes in the road-building and tree-hugging camps.

Seeing that highway engineers had “made wildlife crossings a goal of the project, we said, ‘OK, we’ll go along with expanding it to six lanes,’” Raines says. In the past, the opening gambit of the Sierra Club, for which Raines also works, and other environmental organizations would have been to oppose any expansion. He says that accepting the wider road “had a lot of heartburn” for many in the environmental camp, but they were persuaded to go along in exchange for a top-notch wildlife crossing plan.

Raines allows that “we won’t know whether our approach is going to work until next year,” when the final crossing plan is adopted, but “it’s how you do business in the modern world.”

The trump card of human safety
And if Joe Taxpayer is not impressed by images of critters bounding blissfully through natural passageways over and under the freeway, engineers and environmentalists are both quick to throw a trump card on the table.

Animals on the asphalt are “a human threat as well as a wildlife threat,” says Hilty.

“We may not know everything about the movement of wildlife,” Raines adds, but “we do know what happens when a car hits a deer or an elk.”

Indeed, the National Safety Council says there were 750,000 animal-vehicle collisions in 2000 alone, resulting in 120 human fatalities.

Just a few miles west of the I-90 project area, four people were killed and a fifth critically injured when their car slammed into an elk as it tried to cross the freeway on an early June morning a year ago.

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