Toad Tunnels Help Amphibians Win At Real-Life “Frogger” It's life and death for frogs trying to cross the road

Dear EarthTalk: What are “Toad Tunnels?”

—Sandy Sterling, Worcester, VT

A group of conservation-minded Cornell University students invented “toad tunnels” in 2003 to help amphibians better negotiate a series of risky road crossings to springtime breeding ponds in a nature reserve in upstate New York’s Cornell Botanic Gardens. The students knew that frog populations were already in steep decline around the world for a variety of reasons, and they wanted to help.

toad tunnel
Credit: californiathroughmylens.com

When the students discovered that hundreds of toads, salamanders, newts and turtles were dying on one particular road through the area each spring evening, they hatched a plan. Working with a local polymer company, they designed and installed a “drift fence” to help guide the critters to previously existing culverts underneath the road. The fences—dubbed “toad tunnels” by the students—even curved over on top to prevent hopping creatures from turning back and abandoning their important reproductive missions. After a prototype test saved hundreds of amphibians one night at a particularly difficult road crossing, the students raised $5,000 to install toad tunnels at other key spots around the Cornell campus and beyond.

Cornell’s toad tunnels are just one example of hundreds of innovative structures designed to help wildlife make safe passage around, under or over various kinds of man-made barriers. In Amherst, Massachusetts, similar tunnels help salamanders reach breeding pools each spring—and a “Watch Out for Salamanders” sign alerts drivers to slow down in sensitive areas. And in Utah, fences channel deer across busy state highways around Park City, with white stripes on the roads serving as visual cues for the animals and to alert drivers. Researchers estimate that road kill in the region has dropped by 40 percent as a result.

Sadly, roadways kill hundreds of millions of animals every year. With highways already covering more than two percent of the land in the contiguous 48 states expanding and increasing, wildlife populations stand little chance of surviving the onslaught of automobiles into their habitat.

From the 1950s through the 1970s, the Human Society of the United States sampled road kill data from across the country and estimated that one million vertebrate animals—mammals, birds, reptiles and amphibians—were getting mortally familiar with the wrong end of a car bumper on U.S. roads every single day. But according to surveys conducted over the most recent decade, American motorists are only killing 500,000 vertebrate animals per day.

But Mark Braunstein of the non-profit Born Free USA isn’t sure if that trend means we’ve made progress or if animal species have simply gotten scarcer. Still, others remain optimistic that so-called “wildlife mitigation” efforts undertaken in recent years have been paying off. In the old days, the construction of interstate highways took precedence over environmental concerns. But that notion may be falling by the wayside, as Congress last year allocated a record $3 billion to fund toad tunnels and other ambitious wildlife redirection efforts across the country.

CONTACTS: Cornell Botanic Gardens, cornellbotanicgardens.org; cHuman Society of the United States, www.hsus.org; Born Free USA, bornfreeusa.org.


EarthTalk® is produced by Roddy Scheer & Doug Moss for the 501(c)3 nonprofit EarthTalk. To donate, visit www.earthtalk.org. Send questions to: question@earthtalk.org.