Roadkill study shows more reptiles killed by fence designed to help

An extensive roadkill study on Highway 69 south of Sudbury, shows fencing designed to keep reptiles off the highway failed — and may have resulted in more animals being trapped on the road and getting killed. 

The study, published in the journal PLOS ONE, took two years to complete, with volunteers and biology students documenting reptile roadkill along two sections of the highway.

One section was built with with plastic tarp fencing alongside the highway intended to direct turtles and other reptiles to huge ecopassages or tunnels under the road.

Those results were compared to another section of highway that crossed through a similar ecosystem, without any mitigation.

Study author James Baxter-Gilbert said, "We were seeing 10 times more reptiles using the road to pass, than these ecopassages. We saw an increased level of mortality after the fencing was put up." 

Biologist James Baxter-Gilbert holding a snake. (Supplied)

The problem was the fencing which did not withstand the elements. Baxter-Gilbert said the tarp was "degrading very quickly with rips and tears and washouts." 

"There were issues with it not being installed properly," he added, allowing for the reptiles to pass through hundreds of gaps in the fence.

The study suggested if the fence were effective, reptiles would use the ecopassages, as is the case in other jurisdictions such as Florida, where concrete barriers are to direct reptiles to underground tunnels. 

Cheaper option in the long run?

Despite costing exponentially more, Baxter-Gilbert said he believes a more permanent concrete barrier wall would be cheaper than replacing and repairing fencing, year after year.

Masters biology student James Baxter-Gilbert showing the size of the reptile ecopassage under Highway 69 south of Sudbury. (Markus Schwabe/CBC)

Andrew Healey, environment planner with the Ministry of Transportation, said the tarp fencing on Highway 69 would be repaired this year, with a more permanent solution in the future.

"There's no provincial standard, so everything that's done is almost a trial," Healey said. "We are going to go back and retrofit whatever the fencing standard is in the next couple of years."

Healey said the latest product the Ministry is using is a steel fine mesh fence with steel posts. 

"As we learn, and the science develops, we're required to go back and make improvements," he said.

The fencing costs $40 to $50 per meter, which adds hundreds of thousands of dollars to the Highway 69 four-laning project that is currently underway.

But Baxter-Gilbert believes the cost is worth it.

"The Georgian Bay coast line hosts some of the highest reptile diversity in the country, he said. "A lot of them are endangered or threatened or at risk."