Resolving the conflict between roads and wildlife
Thu, Jul 22 2010 at 3:22 PM
By Kate Frazer for The Nature Conservancy
On the first warm, rainy night of spring, a yellow-spotted salamander emerges from its burrow and sits motionless in the wet grass. On the hill above, cars whir by on the rain-soaked asphalt.
Moving ahead seems dangerous, but his opportunity to breed is short; it could take the salamander a week to make the 1/5-mile journey to the vernal pool where he was born. Suddenly, he notices a wide dim space that seems safe, cool and comfortable. He inches forward and disappears safely into the darkness.
I’m in Princeton, Massachusetts, visiting one of North America’s first salamander tunnels with scientists from The Nature Conservancy and the University of Massachusetts. Come spring, this tunnel and others will be brimming with spotted salamanders, wood frogs and turtles en route to their breeding grounds, but right now it’s full of several feet of packed snow, and UMass wildlife ecologist Scott Jackson is digging it clear with bare hands.
“Animals need to move through the landscape for daily activities like getting food and to complete the migrations that keep their populations strong,” says Jackson. “There’s great habitat here, but the road goes right through it, separating the forests where these species spend the winter from the breeding pools they seek in the spring.”
In an effort to determine where improving connections will make the biggest difference for species including salamanders, fish, mink and moose, the Conservancy and UMass are working together on a project called Critical Linkages that combines digital maps, land-use data and aerial photography with a sophisticated computer model and on-the-ground reconnaissance to reveal the best places across Massachusetts to restore connections.
Throughout Massachusetts, forests have rebounded from widespread clearing, rivers have recovered from decades of industrial pollution and conservation lands are plentiful, but our wild areas are increasingly separated from each other by roads and other developments. This affects not only animals’ ability to move, but also natural processes that people rely upon — such as water flow, plant pollination and seed dispersal.
“We have 3 million acres of forest, thousands of miles of streams and hundreds of thousands of acres of wetlands,” says Andy Finton Conservancy’s director of conservation science in Massachusetts. “But they mostly exist in patches. If we can weave these isolated patches together, we’ll have a stronger fabric. And the more connected our landscapes become, the more resilient the species within them will be to invasive species, forest diseases, and the impacts of climate change.
Sometimes, reconnecting the landscape is as simple as replacing an old culvert to let a river flow more freely. In other cases, it might take protecting hundreds of acres to connect two blocks of forest. “The challenge is focusing efforts on the places that will make the biggest difference,” says Finton.
At his office, Scott Jackson pulls up an aerial photo of the area we visited that morning. “When you take a bird’s-eye view of the landscape, you can see so many opportunities to improve connections, but you can’t fix everything,” he says. “The Critical Linkages model lets us experiment with different connections so that we can see what changes will have the biggest impact.”
On complex maps, forests appear in hues of green and yellow depending on how connected they are, and rivers appear in shades of blue. “See what happens if we were to improve a road crossing here,” says Jackson, typing the change into the model. On the map, the colored lands around the crossing turn darker, showing the degree to which both the forest and river become more connected.
By “reading” these layers of images and data, researchers, conservationists and transportation planners can assess the entire landscape from the point of view of the animals that live there and then invest limited funds for conservation and transportation more wisely.
Back outside, Alison Bowden, the Conservancy’s freshwater director in Massachusetts, shows me a culvert full of rushing water. “There are no rocks here to rest under, the water is turbulent and the structure is small and narrow,” she says.
“A brook trout could probably make it across, but a turtle or salamander wouldn’t really stand a chance.” Structures like these are not only harmful for wildlife, they’re also more likely to fail in major rain events, which can put roads — and people — at risk.
By sharing this information with transportation planners, the Conservancy and UMass hope to encourage actions that accommodate the movement of wildlife. But it’s not just about salamanders getting across. “Improving connections is essential for maintaining healthy ecosystems,” says Bowden. “And making sure the infrastructure we build is compatible with nature is a big part of that.”
Kate Frazer is a senior writer for The Nature Conservancy based in Boston, MA.
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