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Wildlife Tunnels in Vermont Cut Amphibian Deaths By 80 Percent, Study Finds

Streets are deadly for animals—but there’s hope. Animal underpasses in Vermont are drastically reducing amphibian deaths.
ByCaLea Johnson|
Please don‘t hit these little guys.
Please don‘t hit these little guys. | Vlad Georgescu/GettyImages

Thousands of animals, from mountain lions to newts, are killed each year due to vehicle collisions. Traffic is even partially to blame for population declines in some species. Amphibians are especially vulnerable to such threats, but a new study in the Journal for Nature Conservation shows that wildlife tunnels can drastically reduce their roadkill rates. 

According to Smithsonian, the number of amphibians killed by cars skyrockets during their spring migration season, when the animals must travel from forests to ponds, wetlands, and flooded meadows to breed. They’re often forced to cross busy roads, which is easier for spry mammals like deer. Amphibians, on the other hand, move much slower and take more time crossing streets, leading to needless deaths. The fact that they tend to travel on warm, rainy nights also makes them harder for drivers to detect.

But the issue may have a surprisingly simple solution. A team of researchers in Vermont found that two wildlife underpasses in Monkton, Vermont, have decreased amphibian vehicular deaths by 80 percent since they were installed in 2015. The structures span a 0.8-mile section of road that intersects the amphibians’ migration path. Metal grates were also installed in the tunnels to let moisture in and allow the animals to see the moon, which helps guide them. 

The experts compared amphibian roadkill data from 2011 to 2015, before the tunnel installations, and 2016 to 2022, seven years after the structures were completed. For an accurate representation of the underpasses’ effectiveness, they examined the immediate tunnel areas, adjacent buffer zones, and distant control areas. Their calculations indicated that the tunnels were responsible for reducing amphibian deaths by 80.2 percent. That number jumped to 94 percent fewer deaths when the scientists excluded climbing species. The research shows that constructing wildlife underpasses can be a worthy investment in animal conservation.

When tunnels aren’t built for them specifically, some animals take to the sewers to go where they want. A different 2025 study found over 35 species, including crocodiles, snakes, and raccoons, use the sewage system in Gainesville, Florida’s Alachua County to hunt, breed, and travel. More research is needed to understand why animals want to enter these sewers, but scientists believe that some creatures might accidentally end up in the pipes after being swept away by rain. That’s one more reason to design underground passageways with vulnerable animals in mind.

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