You’re driving a dark stretch of highway. The long straightaways make it all too easy to tune out the road ahead. You pass the umpteenth yellow road sign, figuring it’s marking another turnout—and miss that it’s actually alerting you to a panther crossing hot spot up ahead.

For Florida’s endangered panthers, this is a familiar scenario. The state’s Route 41 cuts through some of the big cats’ last remaining habitat in Big Cypress National Park. Collisions have already killed 17 panthers this year.

“That may seem like a small number, but the Florida Fish and Wildlife Conservation Commission estimates that there are only between 100 to 180 panthers in Florida,” said Molly Grace, a conservation biologist at the University of Central Florida. “Given that estimate, roadkill is a major issue.”

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Looking for a solution, Grace decided to measure how well different types of signs alert drivers to watch for wildlife crossing the road. She and her fellow researchers set up a simulated driving experience—basically a very realistic video game—based on conditions along Route 41.

Study participants then “drove” on the simulated highway. Some encountered text-only wildlife crossing signs, while others saw signs featuring an illustration of a panther.

The results? Pictures win.

(Photos: Getty Images; University of Central Florida)

“The picture-based signs did do slightly better than the word-based signs at reducing people’s speed and brake reaction times, which supports that hypothesis,” Grace said. “However, the word-based signs were still better than having no signs at all.”

Grace’s study, published Wednesday in the journal Nature Conservation, also compared driver reactions to static wildlife crossing signs versus the Roadside Animal Detection System, which uses infrared sensors to detect large animals on the road and triggers flashing lights on warning signs. FWC installed the RADS in 2013 along a 1.3-mile stretch of Route 41 in Big Cypress National Park.

Grace found that drivers responded to flashing RADS signs better than static road signs, backing up earlier research in Switzerland that found signs with flashing lights reduced collisions by as much as 80 percent.

The results could help wildlife officials determine what kind of signs to use in roadkill hot spots, allowing more animals to make it safely across the asphalt death traps that cut through their natural habitat.

The Federal Highway Administration estimates there are between 1 million and 2 million collisions between cars and large animals every year in the United States, affecting wildlife populations, costing more than $1 billion in property damage, and leading to 29,000 human injuries.

While constructing wildlife fencing and providing animal overpasses and underpasses are more effective in keeping critters safe from car collisions, those projects are costly—upwards of several million dollars—and harder to install.

Improving signage could be the cheaper, more feasible solution to saving wildlife, but integration has been slow.

“Right now, they’re more popular in Europe than the United States,” Grace said, but she noted that RADS are being tested in Canada, Yellowstone National Park, and Southwest Colorado.

“It’s not just Florida panthers that can benefit from the RADS; more common animals, like deer, black bear, and even alligators can trip the system,” Grace said. “RADS greatly reduces the chance that drivers will habituate to, and ignore, the warning. If you drive past a static ‘deer crossing’ sign every day and never see a deer, you probably eventually tune it out, which could be bad news for you in the long run.”

“This road is a main throughway across the state, connecting Tampa to Miami,” she added. “Its intersection with Big Cypress National Park has been a hot spot for mortality not just for panthers, but other wildlife found in the forest and marsh ecosystems of the park.”