Can American Motorists Yield The Right-of-Way to Wild Creatures? - Florida panther

National Wildlife, Oct-Nov, 1999

Florida's panthers had a problem. Cars traveling through the Everglades on Highway 84 were picking off one or two of the endangered cats each year. With only 30 to 50 panthers in existence, each death was a major loss. When authorities decided to turn this two-lane route into four-lane Interstate 75 in the mid-1980s, many people feared that cars would drive the panther out of existence.

But roadkill is nothing new. Autos have been squashing squirrels and demolishing deer since Henry Ford's time. Recent research shows, however, that roads also destroy habitat, create travel barriers and disturb wild creatures on as much as one-fifth of America's land. "Roads threaten the basic integrity of our wildlife and wildland ecosystems," says U.S. Forest Service ecologist Bill Ruediger. "This will be the conservation issue of the twenty-first century." Fortunately, biologists and engineers are seeking ways to get animals safely across, over or under the roads people need.

In Florida, engineers built underpasses for the panthers at 23 feline-friendly locations. They also extended 13 bridges to provide additional under-road passageways and erected a 10-foot-high fence along 40 miles of the road. The I-75 project began in 1986, and since 1987 not a single panther has been killed by cars on this stretch of highway. "We have essentially eliminated vehicles as a panther mortality factor in this area," says Gary Evink, an ecologist with Florida's Department of Transportation.

For many wild species, however, America's 4 million miles of public roads remain fraught with hazards. The most obvious and deadly peril is collision: About a million animals are killed every day by America's 200 million cars and trucks. Small or slow-moving creatures such as snakes, rodents, amphibians, skunks and raccoons lead the victim list, but no species is immune. More than 100 large animals-including elk, moose, bighorn sheep and even bison-are hit annually in Yellowstone, and last year 19 bears were killed by vehicles on the Flathead Indian Reservation in Montana. Nationwide, about half a million deer annually become bloody hood ornaments-giving new meaning to the word carnage.

Conservationists worry especially about the impact of roads on less populous species. A lynx restoration project in New York failed largely because cars kept killing the cats, and in Texas vehicles are the biggest killer of endangered ocelots. Nearly half of all human-related mortality for the endangered American crocodile occurs on highways in and around the Everglades. And in the Florida Keys, about 44 of the remaining 250 to 300 Key deer, the last population of America's smallest whitetail, are annually killed by cars-three-fourths of all known Key deer deaths.

Roadkill, however, is just part of the problem with pavement. A less obvious but potentially more damaging impact is habitat loss: The right-of-way for a major road may gobble up 5 percent of each square mile it crosses. Already about 1 percent of the United States, an area about the size of South Carolina, is covered by roads and roadsides.

"Even more important is wildlife's avoidance of roadways and the barriers roads create," says Harvard University ecologist Richard Forman. He and others speak of a "road-effect zone"-a swath of disturbance that may stretch a mile or more on either side of the pavement. Traffic noise and movement can stress wildlife and interfere with migration, communication, the dispersal of young, breeding and other behaviors. Forman estimates that about 20 percent of U.S. land falls into this zone.

One recent example of the barrier effect of roads occurred with the southern migration of Canadian wolves into the northern Rockies. The canines moved south rapidly until they reached Interstate 90. Twice, alpha males-the pack leaders and breeders-were killed on that highway. Preventing animals from dispersing can lead to declining populations and genetic isolation, experts say.

To reduce these impacts, conservationists are seeking to close some remote roads and make other roads more wildlife-friendly. An example of the latter approach is the service provided to western toads by volunteers in Sunriver, Oregon. Each spring, toads en route to mating grounds get squashed on Sunriver's Abbot Drive. "These little guys move so slowly that they don't stand much of a chance," says Jay Bowerman, Toad Patrol leader. So, each night during the six- to eight-week breeding season, volunteers cruise Abbot Drive, stopping to escort toads to safety. Patrollers also string mesh along the road to channel migrants into buckets, which are then emptied on the other side. In the past 20 years, the volunteers have saved as many as 1,000 western toads this way.

For animals that cannot be carried across the road, one solution may be to fence them out. When Canadian officials recently widened nearly 30 miles of the TransCanada Highway in Banff National Park (a road formerly known as "the meatmaker" because of roadkill), they built an 8-foot-high fence on both sides of the road. Since the project was completed in 1998, collisions between elk and cars have dropped from about 100 per year to three.