MONKTON — The wildlife tunnels that construction workers this week are beginning to build under Vergennes-Monkton Road are not your typical Vermont Agency of Transportation culvert project.
The low-slung tunnels will enable amphibians to migrate between their habitat in Huizenga Swamp and in the forests of Hogback Mountain without the life-threatening danger of crossing the busy highway.
Special passageways for getting across the road are especially important to slow-moving creatures like salamanders, frogs, newts, snakes and turtles, said Vermont amphibian expert Jim Andrews. He noted that we tend to be aware of roadkill when the species are large, like moose and deer, and pose a danger to drivers, but that these dramatic collisions hurt individual animals but not the species.
“As you get smaller and slower, roads have impacts on populations,” Andrews said. “So when you start talking about turtles, snakes, frog, salamanders the data show that you can wipe out — and we have wiped out — entire populations.”
The new tunnels won’t be the first wildlife crossing structures in Vermont, which has a handful of overpasses, culverts, “shelves,” tunnels and so forth, in locations on Route 9 along the Bennington Bypass, and elsewhere. Vermont’s first wildlife crossing was built along Route 289 near Essex in 1993. But the Monkton project is unique in being purpose built, from a grassroots effort, and not being built as part of a larger ongoing transportation project, according to Chris Slesar, chair of the Monkton Conservation Commission and an environmental specialist for VTrans.
Slesar and Andrews have studied wildlife crossing designs from around the country and believe that the U-shaped Monkton tunnel will incorporate some of the best features and advances in current wildlife crossing design.
On either side of the tunnel, two 100-foot-long “wing” walls will funnel the amphibians into the tunnel. The tunnel will be anywhere from 2 to 4 feet tall, depending on where it’s located in the natural slope from the higher Hogback side of the Vergennes-Monkton Road to the steep drop down to Huizenga Swamp on the northern/northwestern side. Though built for amphibians, the tunnels will also accommodate small mammals such as bobcat, mink and weasel.
Once construction is completed, volunteers will bring in rocks to place along the natural bottom so that crossing amphibians can hide from predators. Otherwise, noted Lewis Creek Association Board President Andrea Morgante, it would be like “a salad bar” for critters that like to eat frogs and friends.