Transportation and wildlife departments are designing a series of “critter crossings” -- underpasses, overpasses and fences -- so that animals aren’t fenced in by roads. The goal is to reduce the harm highways inflict on habitats as suburban sprawl carries roads deeper into forests and wetlands while making roadways safer for humans and animals.
Why Did the Moose Cross theRoad?
By Nick Timiraos
States have pondered why critters cross the road and are spending taxpayer dollars to get them safely to the other side.
Transportation and wildlife departments are designing a series of critter crossings -- underpasses, overpasses and fences -- so that animals arent fenced in by . The goal is to reduce the harm highways inflict on habitats as suburban sprawl carries roads deeper into forests and wetlands while making roadways safer for humans and animals.
Scientists locate potential crossings in areas where animals are known to travel by identifying migration paths or simply noticing stretches of pavement littered with roadkill. They try to create an opening that looks natural and safe for animals. Jeffrey Collins, an ecologist at the Massachusetts Audubon Society, said animals respond better to shorter and wider tunnels and can take months to become comfortable using underpasses.
In Maine, the threat is moose. In Washington, elk. In Massachusetts, deer. Florida has led the way in critter crossings with a series of 24 underpasses and 10-foot fences to protect the endangered panther along 40 miles of Floridas I-75 Alligator Alley constructed beginning in the 1980s. The wildlife crossings and fences have decreased panther road mortalities, according to a 2001 study by the Florida Wildlife Conservation Commission.
California underpasses in the Mojave Desert protect the regions tortoises. Two tunnels in Amherst, Mass., help guide migrating salamanders across a road to warm, fishless mating ponds.
Washington state is scheduled to build a series of wildlife passages in 2011 in the Snoqualmie Pass, a 15-mile stretch of land through dense mountainous forests along I-90. At $100 million, the seven-year project would be the most extensive and expensive of its kind in the United States. But a Washington ballot measure this November to repeal the states gas tax would strip funding from the project, part of a larger highway-widening effort.
Tony Clevenger, a wildlife ecologist at the Western Transportation Institute at Montana State University, said a similar series of 22 underpasses and two overpasses along the Trans-Canada Highway in Albertas Banff National Park have helped decrease elk and deer deaths by 95 percent. Total roadkills are down by 80 percent, Clevenger said.
Now cars arent killing elk, wolves are. With these measures in place, weve seen that these predator-prey relationships have been restored, Clevenger said.
Vermont and Maine both have struggled with the deadly combination of increased traffic and a growing moose population. Moose pose a particular problem because they are slow, large and so tall that headlights often go under their legs, so their eyes dont reflect light at night the same way that deer do.
Maine averages three motorist fatalities each year in moose collisions and warns drivers that they have a one-in-four chance of being injured if they hit a moose. Maine saw 2,068 collisions caused by moose from 1999-2001, with eight human fatalities and 583 human injuries, said Keel Kemper, wildlife biologist with the Maine Department of Inland Fisheries and Wildlife. Numbers that show the effects of moose-crossings are not yet available.
Over the same period, the state saw 12,872 crashes with other wildlife, resulting in two fatalities and 647 injuries. An experimental project in western Maine uses infrared technology to set off flashing lights on warning signs along the highway to alert drivers when a moose is on the road. A similar project in western Washington uses radio collars on elks to trip flashing lights along Highway 101.
But Richard Forman, landscape ecology professor at Harvard University, remains skeptical of systems that use technology to modify human behaviors. Forman said that critter crossings, which began in Europe nearly a decade before the United States adopted them, are still the most effective at reducing roadkill.
Besides reducing the animal death toll, however, wildlife fences and culverts reduce habitat loss by preserving ways for animals to move about, Forman said.
With critter crossings as a starting point, ecologists are encouraging states and the public to reduce further the effects of highways on sensitive habitats. That thinking has made its way to Congress, where last months reauthorization of the federal transportation bill included funds to consider the effects new and existing highways have on sensitive habitats.