Wildlife crossings keep animals, drivers safe in Southwest Florida

The highways, byways and local streets crisscrossing fast-growing Southwest Florida are needed, but come with an unintended consequence: They cut off the state’s wildlife habitat.

Cars are hitting dozens of Florida panthers and black bears a year,often fatally, as the animals cross roads looking for food and potential mates. Some may be searching for new territory as they mature.

These risks to wildlife and humans alike are why state and local agencies are working to build and maintain wildlife crossings. Most drivers are unaware when crossing Alligator Alley — the east-west section of I-75 between Naples and Fort Lauderdale  — that wildlife, even endangered panthers, may be passing underneath the roads.

More:How an endangered Florida panther was guided to safety after getting stuck on the wrong side of a fence

And:Bobcat perched atop electrical pole on Alligator Alley crawls down to safety

When animals are struck on busy roads, those collisions can bring devastating consequences.

In June, one bear, potentially looking for a mate, tried crossing I-75 near Bonita Beach Road. It was hit by five vehicles and died. The southbound interstate was closed for hours.

Between January 2014 and July 2019, the FWC documented 191 Florida panther deaths. Of those, 149 — or 78% — died after a vehicle struck them.

Determining effectiveness of crossings

Providing crossings — underpasses for animals — can help. The first crossings in Collier were built in the early '70s as Alligator Alley was converted into I-75, according to the Florida Fish and Wildlife Conservation Commission’s website.

Data collected and analyzed by the Florida Department of Transportation and agencies like the Federation show crossings have reduced collisions in so-called hot spots on roadways.

In 2015, Daniel Smith, a research associate at the University of Central Florida published “Wildlife Crossing Structures: An effective strategy to restore or maintain wildlife connectivity across roads”, where he explores how well these crossings maintain the safety of humans and animals.

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“By reducing the rate and severity of wildlife-vehicle collisions, crossing structures improve road safety for people and reduce mortality of wildlife ...” he wrote.

The crossings can reduce “the barrier effect of the road, reconnecting animal populations and restoring ecological processes.”

Maintaining the connection between animal populations is vital to the survival of some at-risk populations, said Brad Cornell, policy director of the Audubon of the Western Everglades.

“The Florida panther requires 200 square miles and protects range to the death,” he said. “It will only survive if we keep these landscape connections protected permanently.”

The numerous documented accounts of vehicles striking panthers “speaks to the fact that there is a higher number of panthers out there,” said Meredith Budd, the Southwest Florida field representative for the Florida Wildlife Federation.

There are currently 32 crossings in Collier and Lee counties with the greatest concentration along I-75 as it winds east to west through the Picayune Strand State Forest, the Florida Panther National Wildlife Preserve and Big Cypress National Preserve, according to a map provided by FDOT. There are more on the way.

“We’re cognizant of the barrier that I-75 creates,” said FDOT spokesman Zachary Burch.

One way agencies can understand if the crossings are effective are the use of camera traps placed in the crossings.

“Underpass cameras can let us see what species are using these underpasses and to what extent,” Budd said. “The cameras are the best way to have a metric to quantify success at a small scale.”

Photos of the underpass cameras can be found on FDOT’s Wildlife Crossing map online. They show panthers, black bears, bobcats, alligators and deer.

For the crossings to be successful, fencing needs to be installed that funnels wildlife into the underpasses.

Building the underpasses

“When installed with fencing to keep animals off the roadway and funnel them towards crossing structures, they can also reduce or eliminate wildlife-vehicle collisions and improve road safety,” Smith wrote in his study.

In some instances where panthers are known to prowl, special 10-foot fencing topped with barbed wire is used, Burch said.

“In more developed areas, there is just sort of a cattle fencing, but we put ‘panther fence’ on I-75,” he said.

Since the I-75 underpasses have been built, there have been very few animals killed along Alligator Alley, Cornell said.

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“They cost about $1 million apiece and FDOT was ridiculed by other agencies and road builders as wasting that money,” he said. “When you think about it, all that traffic going through the Everglades so fast, hitting something would be deadly. It’s a huge plus for driver safety.”

With the exception of a few privately built wildlife crossings, FDOT oversees the construction of the underpasses.

Wildlife crossings are put up when FDOT already has projects in the area, Burch said.

“The projects aren’t free, so we want to make sure we put them where they’re most effective,” he said. “FDOT will utilize what’s in place already, like canals."

Each new crossing presents a unique opportunity for FDOT and environmental agencies. Some crossings are culverts built about 8 feet tall and 24 feet wide. In areas with a canal, FDOT will build shelves on the edge so more water-adverse critters can avoid getting wet.

Amber Crooks, environmental policy manager at the Conservancy of Southwest Florida, said the process is adaptive to determine the most effective method.

“We’re concerned when crossings are used as mitigation because we want to make sure they are tried-and-true designs proven to be effective,” she said.

A deer uses a wildlife crossing under Corkscrew Road east of I-75.

When and where should wildlife crossings be built? The transportation department  issues guidelines: Apart from science-based research presented by FWC, the U.S. Fish and Wildlife Services or similar agency, FDOT looks at what wildlife is known to be in the area, the rate of documented roadkill reports and if the crossing would be within the range of Florida panthers or black bears.

A map created by FDOT visualizes certain hot spots, or areas where there is a high occurrence of vehicles hitting panthers. FDOT, and local environmental agencies, can use these maps to determine where best to place the crossings.

“As more hot spots are identified, we hope to continue these projects,” Burch said. “We’re looking at more crossings on the north end of SR 29 and eastern SR 82.”

Burch said FDOT is building two crossings on State Road 80 with five more officially being planned and designed on state roads 82 and 29 and one on I-4.

There are upcoming construction projects to widen SR 29 from Oil Well Road up into Hendry County where more crossings may be built.

A look ahead

Over the next 50 years, Crooks estimates about 300,000 people will move into eastern Collier County, which she said is the last core area for panther habitat. 

A group of landowners drafted a Habitat Conservation Plan that would allow development on 45,000 acres while preserving 107,000 acres for panther habitat.

“(The plan includes) 200 miles of new roadways that come with development,” Crooks said. “This is one of the most problematic areas for panther roadkill, as it would add about 1 million more daily traffic trips by 2050.”

To put that into perspective, Crooks said, the intersection of Oil Well and Camp Keais roads would look more like the intersection of Pine Ridge and Airport-Pulling roads.

The U.S. Fish and Wildlife Service has final say on the plan, Crooks said, and the agency is currently drafting its final decision.

One component of the plan is the Paul J. Marinelli fund, said Cornell. It’s a privately funded “pot of money” that comes from development.

“The fund is estimated to get $150 million in the next 50 years,” Cornell said. “The first $10 or $12 million of that fund is going to be dedicated toward wildlife underpasses. We all recognize those are the most urgently needed.”

More: Injured biker settles suit over panther detection system in eastern Collier

And:Two Florida panthers found dead after vehicle collisions

Opportunities for construction of new wildlife crossings will continue as long as the state sees population growth.

While the Habitat Conservation Plan will focus on Southwest Florida, Gov. Ron DeSantis in May approved a measure to add three toll roads throughout the state.

“I think that when we look at Florida and population growth, and the fact that these toll roads (are coming), I don’t see a slow in construction or maintenance of roads,” Budd said.

With construction and maintenance comes the opportunity to reconnect wildlife habitat with wildlife crossings.

“Roadways segment habitat,” Budd said, “and that is the greatest threat to wildlife worldwide.”

Karl Schneider is an environment reporter at Naples Daily News. Follow him on Twitter: @karlstartswithk