Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration
Office of Planning, Environment, & Realty (HEP)

Wildlife Protection

Keeping It Simple: Easy Ways to Help Wildlife Along Roads

Plastic "Toad Wall" Guarantees Safe Trip to Wildlife Crossing

Boreal toads (listed as endangered by both Colorado and New Mexico) spend all winter hibernating in the mud. Muddy Pass on State Highway 40, where numerous beaver dams provide the shallow, sun-warmed water and soft mud that the toad requires, has proven so attractive to boreal toads that the Colorado Division of Wildlife released more of the mud-loving little critters into the area in 2000. But SH 40 bisects the water course between ponds, so when work began on improvements to the highway in 2003, Colorado Department of Transportation (CDOT) crews took advantage of the opportunity to build an underpass for the toad and other wildlife species. Next to the underpass they installed a fence specifically for the boreal toad. The fence is made of composite plastic boards instead of chemically treated wood, which would leach small amounts of copper and arsenic into groundwater--a potential "poison" to both the toad and its eggs. Installing the fence was easy. Workers inserted the 2x8 boards into a shallow trench so only 6 inches appeared above ground. To direct the toads to the underpass, they laid the boards out in a "V," making each arm 30 feet long. After the fence was completed, observers noticed fewer toad carcasses on the highway and more egg masses were observed on both sides of the road. When the toads emerge from hibernation this spring, CDOT biologists expect many of them will head for the fence and the underpass.
--Aug 21, 2006

Jeff Peterson, (303) 512-4959 or

close-up of a boreal toad
CDOT photo
The boreal toad.

View Photo Gallery

Along Roads - Colorado
Updated: 12/12/2012
HEP Home Planning Environment Real Estate
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000