How did the toad hop across the road?
Helping animals cross at critical choke points
(Page 2 of 2)
Mr. Evink and his colleagues at the Florida Department of Transportation are leaders in a campaign to encourage sensitivity among highway engineers to the ecological effects of their work. Florida is sponsoring an international conference on transportation and wildlife set for this September in Missoula, Mont.Skip to next paragraph
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The idea of helping wildlife cope with disruptions caused by highways is still a new concept. Experts are finding that highways create significant barriers to the natural interconnection among animals within a large region.
Busy highways can split wildlife into small, fragmented populations that are much more vulnerable to population fluctuations because they've lost their ability to roam and interact.
"One percent of the United States is covered by roads and roadsides. That is an area about the size of South Carolina," says Richard Forman of Harvard University in Cambridge, Mass., an expert on the impact of roads on wildlife. "Society hasn't come to grips with the ecological effects of this road system, but it is beginning to."
Some experts suggest examining the problem from an animal's viewpoint. On a typical four-lane highway carrying 20,000 vehicles a day, a car or truck would pass every 4 seconds. "Not many animals are going to get across that road - not alive anyway," says Paul Garrett, an ecologist with the Federal Highway Administration. "Roads effectively can become very solid barriers to a lot of species of wildlife."
At Banff National Park in Alberta, Canada, ecologists are working to mitigate the impact of widening the Trans-Canada Highway to four lanes. They used a combination of fencing, wildlife underpasses, and overpasses, and recorded a 96 percent reduction in road kill of elk and deer.
Grizzly bears, wolves, and cougars regularly use the underpasses. Bruce Leeson, of Parks Canada, says he is confident that the park's two new $2 million overpasses will be just as popular. He says wolves and grizzly bears are very wary animals. "It takes them time to find these new structures," he says. "Then it takes them time to get up the courage to go through them."
In Florida, transportation officials are planning construction of their first wildlife overpass. It will be built south of Ocala and will extend over I-75 at a cost of about $2.6 million. One goal is to encourage bears to roam from the Ocala National Forest to Florida's western coast, where bear populations are isolated and in decline.
In another innovative project, Florida officials are beginning work on a means to keep frogs, toads, snakes, and alligators off State Road 441 south of Gainesville where the road bisects the Paynes Prairie State Wildlife Preserve.
The plan calls for construction of a three-foot-high wall with an 18-inch lip protruding outward to block the slippery critters from crawling or hopping out onto the road. Instead, they will be directed to four culverts under the highway.