An aerial view shows habitat fragmentation in Montana. Amazingly, the Forest Service itself is the world's most prolific road builder. According to the alliance, which has been studying the backroads of Eastern Rocky Mountain parklands since 1994, Forest Service maps are etched with a confusing 430,000 miles of road, with many more uncharted. Only about 30 percent of Forest Service land currently qualifies as secure habitat, says Regnerus. Roads exact their toll on habitat by eroding soil, disturbing the flow of water, and exposing deep areas of forest to disruptive levels of sunlight.
Roads can also impede important animal migration.
A road that sees 10 vehicles a week can keep large animals from crossing it. Roads can be blocked off, chained and even removed to restore the balance of nature, reports Regnerus. And spurred by alliance efforts, the Forest Service is doing just that. There is a small pond here in southwestern Ohio, which, upon its construction, was not stocked with fish. It now has fish, and nobody knows how they got there.