September 25, 2009
Turtles and Highways: Crossing the Killing Zone
Ecopassages help turtles cross a Florida highway safelyBy Matthew J. Aresco
Another 18-wheeler roars down U.S. Highway 27 near Tallahassee, Florida, shaking the roadside brush. A Florida cooter—a turtle hatched on Lake Jackson's shore 15 years ago—steps into the road. The lake is drying up, and she's looking for a new home. A suitable place is only a few hundred yards away, but the open ground ahead is a killing zone for turtles.
I see her familiar silhouette from a quarter of a mile away. Pulling onto the shoulder, I hop out of my car and race toward her, against the approaching traffic. She pulls her head into her shell, mistaking me for real danger. I snatch her off the road with only seconds to spare. But the highway bears the remains of many turtles who weren't so lucky—90 of them in just a third of a mile on the northbound side alone that day.
Lake Jackson is a 4,000-acre State Aquatic Preserve typical of lakes in the area, with a shallow, flat-bottomed, closed basin. The water depth fluctuates widely. About every dozen years, most of it dries. The four-lane highway was built across a corner of the lake in the 1960s—before wetland protection laws—isolating a 50-acre part of it now known as Little Lake Jackson. The highway carries about 23,000 vehicles each day, presenting a lethal barrier for many wild animals.
As spring nears and the turtle migration intensifies, I patrol the roadside for hours. While Lake Jackson is slowly drying, Little Lake Jackson has plenty of water—and the turtles know it. But the traffic prevents me from saving many of them, and time after time I watch helplessly from the shoulder as a 20–30 year old turtle is run over.
Something had to be done, so I proposed a simple, low-cost temporary solution to the Florida Department of Transportation (FDOT)—a low nylon silt fence to direct turtles away from the road and into a large drainage culvert connecting the lakes. The FDOT donated the material, and I constructed fences along each side of U.S. 27.
I monitored the fences daily, transporting the turtles I found walking along it across the highway in large plastic containers. From April to August the fences prevented almost 5,000 turtles from entering the highway in their move to Little Lake Jackson—along with a variety of snakes, frogs, and alligators.
After heavy rains that September, turtles began migrating back to Lake Jackson—3,300 in all as the lake refilled the following spring and summer. Again the temporary fences and intensive daily monitoring saved 99 percent of them from being killed on the highway.
With the end of the drought—and of the turtles' return migration—I hoped that the crossings would subside. But the turtles kept coming in natural local movements to nest and as males and juveniles dispersed.
Death from vehicle collisions is an increasingly significant threat to turtle populations—and those of many other long-lived animals. Recent studies in other parts of North America provide strong evidence that traffic mortality and habitat fragmentation reduce local populations of freshwater and terrestrial turtles along highways.
How can we solve this problem at Lake Jackson and elsewhere? While silt fences are an effective short-term solution, they require constant monitoring and maintenance to be effective. The material degrades rapidly in direct sunlight and is easily damaged by mowers, vandals, all terrain vehicles, and storm water runoff.
Permanent wildlife crossings—ecopassages—offer an answer. Ideally, ecopassages should be designed to lessen the effects of highway mortality and habitat fragmentation for all wildlife affected by a particular road. The FDOT recently constructed a prototype multispecies ecopassage near Gainesville—a lipped, four-foot-high concrete guide wall with a series of culverts under the highway. The system has virtually eliminated roadkill.
Mobilizing local effort
Over the last two years, I have begun a grassroots effort to work with the Florida Department of Transportation, Leon County government, and other agencies to secure funding and to assure the construction of a permanent ecopassage along U.S. 27 to prevent future mortality of turtles and other wildlife. I established a website, www.lakejacksonturtles.org, and a citizen's action group, called the Lake Jackson Ecopassage Alliance, in order to develop and demonstrate broad-based support for the Lake Jackson Ecopassage. Recently, the Florida Department of Transportation allocated $125,000 for a feasibility study to determine the most appropriate design to solve this unprecedented road mortality problem and to reestablish natural migration patterns.
Although the design and construction of a permanent ecopassage may still be years away and funding sources remain uncertain, this is an important first step toward meeting Federal Highway Administration (FHWA) requirements for possible Federal funding or Florida Department of Transportation's Ecosystem Management funds. In the meantime, I continue to walk the fences and carry turtles across the highway in plastic containers with duct tape in hand to patch the holes. As I watch the rainfall deficit increase for 2004 and the lake level slowly drop, I ready the fences for another mass migration of turtles.
A final word
The migration of thousands of turtles at Lake Jackson and their ability to find water during drought is truly an incredible natural wonder. Turtles possess a tenacity for survival that reflects millions of years of adaptation to dynamic environments. Yet the resiliency of turtles is too often overshadowed by their vulnerability to habitat destruction and fragmentation and the dangers of roads and highways. A migrating turtle knows where it wants to go and moves with single-minded purpose toward its goal. As stewards of the environment, we should follow that example and ensure that turtles and other wildlife are protected from the hazards that we create.
To learn more, contact
Want to help? Send a letter or e-mail supporting ecopassages to the following key decision-makers.
Leon County Board of County Commissioners
Leon County Courthouse
301 South Monroe St.
Tallahassee, FL 32301-1853
Tallahassee-Leon County Planning Department (MPO)
Mr. Jack Kostrzewa, Acting Director
300 South Adams St.
Tallahassee, FL 32301
Matthew J. Aresco is the Lead Biologist, Lake Jackson Ecopassage Alliance. This article appears, in a slightly different form, in the Summer 2004 issue of Wild Neighbors News.