Extension Highlights

Make Way for Turtles

Why did the turtle cross the road?

While it’s hard to know for sure, says Scott Jackson of Extension’s Natural Resources and Environmental Conservation (NREC) Program, it could be because there wasn’t a properly sized and sited turtle tunnel beneath the road.

At any rate, if declining turtle populations are any indication, crossing the blacktop was probably not a great idea from the turtle’s perspective.

And just what is a properly sized and sited turtle tunnel? That’s the question that Jackson and a team headed by Paul Sievert of the U.S. Geological Survey’s Massachusetts Cooperative Fish and Wildlife Research Unit is trying to discover at an odd experimental installation at UMass Amherst’s Tillson Farm. The project is also calling on the resources and talents of Brad Compton of the UMass Amherst Natural Resources Conservation Department and graduate student David Paulsen.

The scene at Tillson Farm could, perhaps, be mistaken for something of a rodeo or steeplechase for turtles. When the weather permits, spotted and painted turtles lumber through various configurations of conduit, being timed and photographed as they go. They generally have one or two hours to make their way through the tunnels of up to 70 feet in length unless, of course, they decide to take a nap somewhere in the middle.

Under a three-year $155,000 research project funded by the Massachusetts Highway Department and the Massachusetts Division of Fisheries and Wildlife, the UMass Amherst team is looking to turtles themselves to determine what kind of tunnel works best. They are looking at a range of variables: tunnel sizes ranging from 2x2 feet to 4x8 feet, lengths running from 40 feet to 70 feet, tunnels at below grade level, and tunnels with varying openings for light and air.

While turtles themselves have a clear interest in the outcome of the study, the targeted beneficiaries are actually the folks who are trying to build highways. The ultimate funder is the Federal Highway Administration.

The optimum size of a turtle tunnel is not the only thing that is unclear. Turtles are surely in decline, says Jackson, but it’s difficult to pin down the shape of the decline. Everything about turtles seems to happen in slow motion.

“A turtle can be rare or in trouble,” he notes, “but it takes a long time for the decline to become evident when a species has a life span of 100 years or so. Recent research suggests that spotted turtles may require a reproductive life span of 40-60 years to ensure population stability over the long-term.”

Although some turtles such as spotted, box and wood turtles are still found at many sites across Massachusetts, there is concern that – for many of these sites – the number of turtles is very small. There can be a small handful of turtles, or even a single individual. These very small populations may be ghost populations, lingering vestiges of past abundance that are unlikely to persist over time.

Jackson himself has spent much of the last 20 years at the center of the effort to give reptile and amphibian populations a fighting chance to survive the encroachment of development, through the use of tunnels under roadways. The whole world was watching Jackson and colleagues when, in the 1980s, Amherst’s Henry Street salamander tunnels tested a European approach to the problem.

While that experiment won the hearts of the onlookers and the news media, it did little to answer key questions about what exactly constitutes the best tunnel.

“Until recently, we haven’t known much more than we did back then,” he says.

While the study is just entering its second year, he adds, it already appears that when it comes to tunnels, turtles prefer bigger and at grade level.