Highways are deadly barriers to wildlife, so Massachusetts is putting tunnels beneath highways to help animals cross safely. New data shows these wildlife passages may be more effective than anyone thought.
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To get to the wildlife tunnels under Route 2 in Concord, you have to trudge through woods teeming with mosquitoes, ticks and poison ivy. As you get closer, the roar of the four-lane highway gets louder.
"There's the entrance to the tunnel," says Lydia Rogers, who co-chairs a volunteer task force that's keeping track of how many animals use this passage.
"Let's go inside. See already how much the sound changes?"
The echoing tunnel is basically a concrete tube that stretches all the way under Route 2. At six feet high and even wider than that, it's easily big enough for people. In the center of the tunnel is a sandbox. When animals walk through it, they leave their tracks.
"We have an opossum going south, we have a chipmunk going south, a raccoon coming north, we've got a woodchuck going north. We have a frog coming north," Rogers says.
"This is another frog, it looks like going south. We have a mess of chipmunks, probably six or eight. Here's another woodchuck, that one's going south."
Rogers checks the sandbox about twice a week to look for new tracks. She expected animals to go through the tunnels, but she's shocked by the number and types of animals that use them — more than 30 different species.
"For instance, right over here — oh, and a snake! A snake has used it," Rogers says. "Now that's so cool."
Minks, weasels, foxes, muskrats, beavers, doves, whitetail bucks. Even raccoon families and fisher cats carrying prey. All of them have used it.
A lot of the animals have been photographed by infrared cameras that snap pictures when they sense heat or motion. In the three years they've been filming, the cameras have taken thousands of photos. Some of them show amazing scenes.
"Oh — a deer went swimming through when the tunnel was flooded," Rogers says. "And that one to me is so remarkable because that means that deer was comfortable enough with that manmade structure that it would swim through to the other side."
The Massachusetts Highway Department built this tunnel, and three others like it in Concord, to help animals cross Route 2 safely.
Fifty thousand cars a day race along this road, straight through woods and wetlands that are home to thousand of animals. If those animals can't cross Route 2, they can have trouble hunting, breeding, and raising their young.
"Roadways are an obstacle to animals and the more you fragment their habitat," says Kevin Walsh, director of environmental services for the MassHighway, "you're preventing them from possibly expanding their diversity of species."
Tunnels also benefit drivers by keeping animals off roads. The tunnels in Concord are monitored by a group of volunteers organized in part by the town and Sudbury Valley Trustees, a conservation group.
Scott Jackson (read his papers), a wildlife biologist at the University of Massachusetts, says it's rare for wildlife tunnels to be studied as closely as this.
"Often when these things are built there's very little effort put into monitoring them so you can't really tell how successful they are or are not," Jackson says. "In this case, thanks to the people in the area that came together to monitor this structure, we actually do have data."
The cameras and sandbox show that Concord's tunnels are extremely effective, says Walsh of MassHighway.
"It's been fantastic in that we actually have pictures of the animals using it, we have pictures of the tracks," Walsh says. "The quality of the data is fantastic. It's a success."
Nature lovers such as Lydia Rogers hope that success will lead to more wildlife tunnels. Rogers wonders, though, if the tunnels could be getting even more animal traffic. That's because there's one species using them that shouldn't be.
"We have had people bike through, snowshoe through, walk through, some of the other tunnels they have boated through," Rogers says.
Signs explain that wildlife monitoring is in progress, but some people use the tunnels anyway. And if people use them, animals might be afraid to. Because of that, Rogers prefers that not too many people know where the tunnels are.
State and federal funds pay for them. In Concord, the four passages cost $400,000 out of a total road reconstruction cost of $5.4 million. Rogers says that's a deal when you consider the car accidents avoided and the benefits of reconnecting wildlife habitat.
"Wherever you do road construction, put in a tunnel. Okay, so you can't make it big enough for people to ride their bike through — great!" Rogers says. "It is for animals. Just put them in."
There are more than 500 wildlife tunnels nationwide and at least a dozen in Massachusetts. MassHighway says it's designing more tunnels for safe wildlife crossings.