One Picture Is Worth a Thousand Models
Game Camera Studies Ground Truth Wildlife Connectivity in Vermont
People love seeing wildlife, except when it’s a half-ton moose standing in the middle of a highway, caught in the glare of headlights. Deer-related automotive collisions alone resulted in $3.8 billion dollars in insurance damage claims nationally last year.
“When wildlife ventures onto roads and highways, the results can be devastating for people and animals,” notes Vermont Fish and Wildlife Department conservation planning biologist Jens Hawkins-Hilke. “In addition to creating roadkill, highways act as barriers that can halt animal migration, isolating wildlife and promoting inbreeding among disconnected populations.”
Now two groundbreaking Vermont studies are seeking ways to decrease collisions, while increasing wildlife connectivity. The research is being conducted through a unique Staying Connected partnership between the Vermont Agency of Transportation (VTrans) and the state’s Fish and Wildlife Department, along with private engineering firm McFarland Johnson, as well as the Vermont chapter of the Nature Conservancy, and the University of Vermont’s Transportation Research Center.
“We’re studying ways to evaluate and improve wildlife migration corridors where they cross busy highways by taking pictures of animals,” says Hawkins-Hilke. The two Vermont studies are deploying game cameras equipped with infrared triggers to determine the abundance of wildlife species near roadways, and to see if, and how often, animals are using various-sized stream culverts and bridges to cross under roads. The hope is that, over time, as culverts and bridges need to be replaced, that they can be minimally and economically redesigned to be more inviting to migrating animals.
I-89/Rte. 2 Game Camera Study, North and Central Green Mountains Linkage
The first game camera study began in June 2013 and is slated to run for two years. The study is located along a busy stretch of I-89 and U.S. Rte. 2 between Waterbury and Bolton Village—a section of highway that is among the most frequented by moose, according to State Police statistics.
“These wildlife studies are helping solidify a growing interest in enhancing wildlife connectivity where it’s now blocked by roads and railways. VTrans is very receptive to the concept, and it’s a great experience figuring out creative connectivity solutions. It’s a win-win for highway safety and for wildlife.”
– James Brady, Environmental Specialist, Vermont Agency of Transportation
“The Green Mountains represent one of the largest unfragmented forest habitats in the Northeast, and the I-89 corridor is easily the biggest break in that habitat,” explains Jed Merrow, Environmental Project Manager for McFarland Johnson.
“This to a wildlife rich area, with mammals such as bobcats, bear and moose moving through it. But no one knows to what extent they can cross the corridor,” says Merrow. “If they can’t cross, that has negative implications for population health and genetic mixing. Our purpose is to find out if and where they are crossing. We want to know what kind of transportation structures they’re currently using, and what kind of improvements we can make in the future to enhance movement.”
Since 2011’s Tropical Storm Irene, Vermont has made a dedicated effort to enlarge undersized bridges and culverts—increasing stormwater capacity, and hopefully, animal movement as well.
The study’s forty game cameras are stationed in stream culverts and beneath bridges along I-89 and Rte. 2, with others placed at either end of 1,600-foot long transects to see if wildlife is moving parallel and close to roadways. Still others were placed in transects a mile or more distant, as a control to compare population density far from the highways.
The project, still in its early phase, has already yielded remarkable candid images. “We’ve got hundreds of pictures of deer, bear, moose, bobcat, coyote, fisher, flying squirrel, white-footed mice, and turkey,” says Hawkins-Hilke. “But there is very little evidence so far of movement across Rt. 2 and I-89.”
Knowing exactly where wildlife is plentiful on either side of the highways is important to planners. It means that the next time highway infrastructure nears the end of its design life or becomes compromised during a major storm, VTrans will know where the highest animal concentrations are located, and where the state can get the most bang for its infrastructure buck when designing replacement culverts and bridges.
“We have beautiful computer models and layered maps to show habitat and where we think animals will cross,” says VTrans Environmental Specialist James Brady. “But that doesn’t necessarily tell us where they are really moving. This study is designed to convince decision makers who are approving expensive infrastructure projects of exactly what is happening on the ground. It helps ensure that if we invest in infrastructure for connectivity in an area, that it will enhance wildlife movement and reduce collisions.”
“Our preliminary data shows very little connectivity in the I-89 corridor now,” reports Merrow. “Once we find wildlife hotspots on either side of the road, we can see if there are bridges and box culverts in proximity that might be enhanced, maybe with fencing that channels animals to those structures and away from the highway, or perhaps by adding a dry shelf to a culvert or bridge’s stream channel which would allow easier passage.”
VTrans is already experimenting with just such a connectivity enhancement. They’ve used leftover soil from recent highway projects to create a sandy wildlife shelf under I-89’s Little River Bridge. “Hoofed animals such as deer and moose don’t like to walk on rocks,” relates Hawkins-Hilke. “So this should entice them, though we’ll have to wait and see what the cameras show.”
Roadway Game Camera Study, Worcester Range to Northeast Kingdom Linkage
A second important Vermont game camera study, this one in the Worcester Range to Northeast Kingdom wildlife linkage, got underway in 2014. The two to three year project involves sixty game cameras, also called “critter cams,” installed at select culverts and bridges along highways. It will be the biggest study of this kind in the Northeast to date.
“We’re using computer models to determine where wide-ranging mammals are most likely to cross roads between two habitats, and where those crossings coincide with culverts and bridges,” says Paul Marangelo, Conservation Ecologist for the Vermont Chapter of The Nature Conservancy. Streams, he notes, can be popular travel corridors for animals, since they offer cover, food, and a hidden route for crossing under roads.
“The question this study is asking is, ‘How do a wide variety of wildlife respond to different sized bridges and culverts?”’ says Marangelo. “Scientists will be systematically comparing wildlife use of 1 to 5 foot diameter structures, with 6 to 8 foot structures, versus 10 foot structures, versus large extended bridges.”
“As climate change progresses, animals will need to be able to adapt, shift their ranges, and move into new habitats. Improving the wildlife permeability of highway structures is one way of addressing that issue. The more you connect habitats, the more robust you make the environment to stressors such as climate change.”
– Paul Marangelo, Conservation Ecologist, Nature Conservancy Vermont Chapter
“There have been studies done out West which categorized wildlife use of transportation structures by the size of the structures and the willingness of various species to use them. We’re using those studies as a guide to see if the results hold up in our neck of the woods,” says Marangelo. “Eventually we’d like to be able to look at a road segment and be able to suggest focal areas for creating the best opportunities for wildlife to cross under highways, reducing vehicle collisions.”
Vermont’s two game camera projects represent cutting edge science. The data collected at Waterbury-Bolton and in the Northeast Kingdom could one day help reduce roadkill and animal collisions, and enhance wildlife connectivity across New England.
Hawkins-Hilke views the projects as a new model for conservation: “What we’re seeing here in Vermont is one agency working closely with another to plan years ahead,” he says. “The long-term proactive partnership between state wildlife officials and transportation planners around wildlife connectivity is fiscally responsible and the envy of other states.”
“Vermont VTrans has led the way in wildlife and transportation issues for more than a decade now. They understand that better connectivity not only benefits wildlife, but also human health and safety, reducing the risk of collisions between vehicles and animals. Improving connectivity benefits wildlife and people.” – Jed Merrow, Environmental Project Manager, McFarland Johnson
“What’s exciting about these projects is that everyone is on the same page,” agrees Brady. “Everybody wants to have a healthy ecosystem in our state, and safe roads too. Everybody also realizes how expensive it is to replace infrastructure and these studies assure us that we have everything figured out in advance so when it comes time to spend highway money, we do it right. If these structures can handle the next Tropical Storm Irene and a moose can walk through them too, all the better!”