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SOURCE: Science Daily

DATE: November 6, 2019

SNIP: Roads define the very fabric of our civilization, and very few places in North America remain road-less. As an integral part of the landscape, roads and their vehicle traffic also have unintended consequences for wildlife: many animals die as a result of vehicle strikes, and some strikes pose a risk to human lives. Think about the consequences of hitting a moose, bear or deer on the highway at 70 mph.

These types of events capture a lot of attention, and management agencies work hard to minimize the chance of wildlife-vehicle strikes through mitigation structures such as wildlife fences and overpasses.

However, the effects of roads are not limited to animals dying on roads. Roads may affect the way animals use their habitat. They may bisect important connections between habitats and populations, or they may deter animals altogether and increase their stress levels because of traffic noise, light or vibration.

These types of effects are what former Ohio University Biological Sciences graduate student Marcel Weigand in Dr. Viorel Popescu’s Conservation Ecology Lab sought to investigate and have recently been published in the European Journal of Wildlife Research.

With a passion for reptiles, Weigand asked how new high-traffic roads affect the ecology, behavior and physiology of Eastern Box Turtles, a species of concern in Ohio, threatened by road mortality. Weigand found the perfect study setting, the new Nelsonville Bypass (U.S. 33), cutting through Wayne National Forest, and opened to vehicle traffic in 2013. Several other wildlife studies have been under way in the same location, investigating the success of mitigation structures to reduce road mortality for deer, snakes, and amphibians, so focusing on turtles would paint a more complete picture on the effects of the new highway on road-naïve wildlife.

Weigand also scouted a roadless study site, not far from the Bypass, on the Hocking College and Wayne National Forest lands; this would serve as a control test site, against which any potential effects of the Bypass could be compared.

For two years (2017-18), Weigand, aided by a horde of undergraduate OHIO and Hocking College students, tracked 30 Box Turtles (15 along the Bypass and 15 at the roadless site) via VHF telemetry on a daily basis between March, when turtles come out of hibernation, and October, when they dig down deep for their long winter sleep.

However, the researchers discovered something rather puzzling — while many turtles used the open roadside habitat created by the new highway for thermoregulation and nesting, with several female turtles spending many weeks during summer within a few feet of the pavement, no turtles attempted to cross the road.

“We were confident that we would see crossing attempts, as Box Turtles crossing roads are a common sighting in this part of Ohio. Instead, the new highway acted as a complete barrier to turtle movements; so, in the absence of crossing structures, such as underpasses, the highway has the potential to completely separate the local Box Turtle population,” Popescu says. “Interestingly, a four-foot wide culvert underneath the highway was available to Bypass turtles for reaching the other side, but no turtle accessed this mitigation structure. Cutting gene flow may have long-term negative impacts on the viability of turtle populations and decrease their ability to cope with other threats.”