Highways' Hidden Toll

Pulling his white Volvo station wagon over to the westbound side of Route 2

ALSO SEE: MULTIMEDIA: Roadside Detractions (Requires Flash, available free from Macromedia.)

about 10 miles outside Boston, Richard T.T. Forman sums up his feelings about his research site.

"This is awful," he says.

The smell of exhaust fills the air as cars scream by at 60 miles per hour. Mr. Forman has to raise his voice to be heard over the constant rumble of tires against road. On this warm spring day, road salt lingers where pavement meets dirt. Trash litters the forest abutting the road: hubcap, soda cup, plastic bag, beer bottle, paper scraps. A scientist exploring the environment along the highway here risks serious injury from speeding cars just a few feet away.

But those problems also threaten animals living near roads. That's why in the past few years, Mr. Forman, a professor of landscape ecology at Harvard University, has become the country's primary evangelist for the budding field of road ecology.

With four million miles of road in the United States alone, streets and highways create major problems for wildlife. But until recently, ecologists paid little heed to those areas affected by roads, choosing instead to focus on unspoiled territory. To encourage further work, Mr. Forman has gathered scientists who have pioneered the nascent field to write a book called Road Ecology: Science and Solutions, to be published in November by Island Press.

Not satisfied merely to create a new academic field, Mr. Forman also invited transportation specialists to join the book project. Together, the 14 authors hope the volume will influence plans for road building and improvement as well as research.

"Not very many ecologists have paid attention to the roads, and not very many road professionals have paid much attention to ecology," says Daniel Sperling, director of the Institute of Transportation Studies at the University of California at Davis and, along with Mr. Forman, the book project's main organizer.

The book should be a "catalyst" for engineers and ecologists to work together in state departments of transportation, says Kathryn P. McDermott, director of technology transfer at North Carolina State University's Center for Transportation and the Environment. "I think they're going to be really excited about this book," says Ms. McDermott, who is not involved in the project.

Offroad Worries

Anyone who has seen a dead raccoon by the side of a busy highway, cleaned splats that once were insects off a windshield, or played the video game Frogger knows that roads are a menace to animals. State and federal transportation departments have become more concerned about nature ever since the National Environmental Policy Act, enacted in 1969, required environmental review and public input for road projects.

Road ecologists study the asphalt death toll, but they worry more about the larger scale, in part because they have discovered that a road's effects can extend hundreds of yards from the roadside and sometimes even farther. Roads can pollute streams, divide populations of animals by fragmenting their habitat, spread nonnative species planted in the right of way, and degrade ecosystems with noise or pollution.

Even roadkills can reduce the overall populations of animals, Lenore Fahrig has found. The professor of biology at Carleton University, in Ottawa, started to wonder about amphibians on her monthly drives to her parents' house, an hour away via two roads, each of which runs alongside a river.

"There seemed to be a lot more squished frogs on the road with the light traffic, which seemed opposite to what you would predict," she says. Guessing that mortality on the more heavily traveled road could have reduced the frog population, she decided to study amphibians near roads south of Ottawa.

By listening to the chorus of croaks, she estimated the density of frogs and toads living near several stretches of the roads and compared the estimates with the numbers of dead amphibians she found there.

What she found confirmed her suspicions, she reported in Biological Conservation in 1995. Frog populations were smaller near heavily traveled roads.

Ms. Fahrig thinks amphibians are especially vulnerable because they don't avoid roads. "Near a river on a rainy evening, they're just on the roads, on the move," she says. Mammals often wait for a break in traffic before they cross. And reptiles may be particularly susceptible to collisions: They come to roads to sun themselves. She suspects that animals' behavior around roads may affect whether roadkills can decimate their populations. "And there's almost no information about that in the literature," she says.

Silencing Birdsong

Because such ignorance about roads pervades ecology, the new book seeks to map existing knowledge and define the most important issues for study. One key area, the authors agree, is determining how animal populations fare near roads.

Mr. Forman recently discovered that the amount of traffic dictates how far birds stay away from a road. The grassland birds he studied in Boston's western suburbs thrive close to smaller roads, but bobolinks and eastern meadowlarks never nest -- and rarely visit -- fields within about three-quarters of a mile of highways like Route 2, with more than 30,000 cars passing per day. His study appears in the current issue of Environmental Management. (He suspects, though he has not proved, that traffic noise scares the birds away.)

Most important, he found that the birds avoid fully half of the area in his study. He thinks that all suburban areas are similarly unfriendly to birds.

In another study, Mr. Forman explored the environment along 15 miles of Route 2, finding invasive plant species, drained wetlands, polluted ponds, and places where animals cross the road, or try to. He then mapped the stretch of road, indicating how far its influence reaches.

In some spots, the terrain he calls the road-effect zone was very narrow, because of built-up areas (which are already disturbed ecologically) or embankments that reduced noise. In other places, the effects extended hundreds of yards from the road. He has identified areas where nonnative plants have spread into the environment and others where road salt contaminates pools of water present only in the wet springtime. Amphibians thrive in those vernal pools because fish, their main predators, don't live there. But the road salt and chemicals from cars also harm frogs and toads because their skin is so porous.

Stopping alongside a stream that runs perpendicular to Route 2, Mr. Forman points out how straight it is. Road builders "channelized" the stream -- straightened it -- for the length of five football fields.

"Channelization is one of the worst things ecologically for a stream," he says. A stream's natural curves create niches for wildlife. But road planners straighten waterways to avoid highway flooding. "The goal," he says, "is to get the water out of here, fast."

This stretch of Route 2 was built in 1935, but Mr. Forman says that channelization is still common for building roads that cross streams. Still, with a greater understanding of the movement of water and animals and other ecological concepts, he says, road planners and engineers should be able to do less damage to the environment when building or upgrading roads. For example, if the road planners had put Route 2 on higher ground, raised the road on pillars, or perforated it with pipes that would allow water to flow beneath it, flooding would not have been a concern because the road would not have served as a dam.

The book will describe solutions that engineers and environmentalists have developed to solve ecological problems in various locations. To allow animals to cross roads, people can build overpasses or underpasses. Europe, with its high-density population, has already built many such structures, but fewer exist in North America. One exception is Florida, where road crews have put up fences along Interstate 75 and built underpasses to allow the endangered Florida panther to cross.

Banff National Park, in Alberta, Canada, boasts one of the most extensive series of wildlife crossings on the continent. Parks Canada installed 22 underpasses of varying designs and two 164-foot-wide overpasses along the Trans-Canada Highway to prevent roadkills of large carnivores, such as grizzly bears and cougars, and their prey, including deer and elk. The park service then hired Anthony P. Clevenger, an independent research ecologist and an adjunct professor of environmental design at the University of Calgary, to determine how animals were using the structures. He installed cameras and sand pits to record the tracks left by animals using the crossings.

Some animals, such as grizzly bears, wolves, deer, and elk, preferred overpasses and the wider, more open underpasses, he found. But not all. Cougars and black bears, which normally skulk in the forest or in thick bushy areas, preferred narrower underpasses.

He found that fences and crossing structures had reduced roadkill by 80 percent over all and by 97 percent for elk and deer.

Mr. Clevenger, one of the book's authors, says he gets "I don't know how many e-mails a week" from transportation professionals seeking advice about building wildlife crossings. Although the book will not make specific recommendations for such structures, it will present what's known about how well the different options work.

Hope on the Horizon

The idea, the road ecologists say, is to get transportation professionals to start thinking more ecologically. Although engineers and planners study the environmental impacts of a projected road, they look in a narrow strip surrounding the pavement. "It's not very holistic," says Kevin E. Heanue, another author of the book and a consultant who formerly served as the Federal Highway Administration's director of environment and planning.

And so far, transportation experts seem interested. The Federal Highway Administration was the book's first financial sponsor, and the Transportation Research Board, an arm of the National Academy of Sciences, has convened a number of panels on related topics.

James L. Sipes, a landscape architect at Jones and Jones, a Seattle firm, has seen firsthand that it is difficult but not impossible to develop ecological awareness. The Montana Department of Transportation recently brokered a deal with local Indian tribes to upgrade a 56-mile stretch of U.S. Route 93 that, when finished, will bear 44 wildlife crossings at a cost of millions of dollars. The department originally planned ordinary upgrades for the road, but because the highway ran through the Flathead Indian Reservation, the state needed the agreement of local tribes, which insisted on provisions for animal crossings.

"The project had been stuck for about 10 years," Mr. Sipes says. After his firm held talks with the state, the tribes, and the Federal Highway Administration in 2000, and after all the parties visited the Trans-Canada Highway in Banff, they agreed to the design.

"There are so many projects that are done from an environmental standpoint so badly," he says, "that ... we have to come in and spend an awful lot of money to fix them. We can environmentally do it right the first time." But his experience has taught him that success comes only when local communities fight for it. He says it sounds as though Road Ecology will help improve the situation. "If you make an argument in the language that engineers can understand, I think a lot of people are willing to do it."

Of course, not everyone is convinced. Bethanie Walder, executive director of the Wildlands Center for Preventing Roads, in Missoula, Mont., argues that the road ecologists' mitigation strategies may not be enough. "What Wildlands CPR is very interested in doing right now," she says, "is seeing the same kind of research take place on road removal," which is happening in several U.S. national parks. "I think the mitigation information that's coming out now is incredibly valuable, as long as we recognize that it doesn't make those roads invisible. It just lessens their impact."

But Mr. Forman holds out hope that with more ecologically friendly planning and upgrading, roads and wildlife can coexist. "There's a massive road system and a massive inventory of vehicles," he says. "I'm smart enough to know that in three years, we're not all of a sudden going to see animals running across highways without getting killed. On the other hand, the public has been beating up on transportation [departments], state after state after state, for not being very environmentally attuned. The transportation community has a lot of good people. They want to do things right.

"I have some feeling," he continues, "that this book might be a catalyst, might be a nugget, might be a gem we can look back on 10 or 15 years from now and say, 'That brought it together. Look how much better it is today.'"