How did the toad hop across the road?
Helping animals cross at critical choke points
AT MILE MARKER 78, ALLIGATOR ALLEY, FLA.
About a quarter of the way from Naples to Fort Lauderdale on this remote cross-Everglades highway in Florida, the interstate passes over a grassy culvert.
To most motorists zooming past at 70-plus miles an hour, the bridge is nothing more than a thud-thud under their radials.
But if they actually pulled over to the side the road and clambered down the steep embankment, they would find themselves face to face with an environmental innovation that is changing the way highways are being designed around the world.
Here in Florida, they call it a panther crossing. In Canada, the same idea works for elk and deer. In England, a much smaller version helps keep migrating toads in hopping form.
The basic strategy is to create a safe, natural means for wildlife to cross a road without endangering their own lives and those of unsuspecting motorists.
Highway planners and ecologists in Florida came up with the idea of a wildlife underpass more than a decade ago when major improvements to Alligator Alley (see map) threatened to isolate a large section of the Big Cypress National Preserve.
They needed to find a way to keep animals off the road. But they also needed to allow animals - like the endangered Florida panther - to continue to hunt and roam in their native habitat on both sides of the highway. The solution: fence the entire length of the highway and funnel the wildlife into culverts passing safely under the traffic.
It wasn't cheap. Thirty-six culverts were constructed along a 40-mile section of Alligator Alley at a cost of $13 million.
But today, the project is hailed as a shining success and has been studied by engineers and ecologists facing similar problems in Canada, Mexico, Australia, and countries throughout Europe. Some ecologists - including pioneering environmentalists in the Netherlands - have taken the concept one step further with the development of wildlife overpasses.
It is all aimed at helping to reduce the negative impact of highways on natural ecosystems.