As they thread their way north, members of the Florida Wildlife Corridor Expedition have come across one of their biggest barriers - Interstate 4. And if humans have a hard time crossing the busy highway -- what does that mean for wildlife?
Expedition members have paddled through the heart of the Everglades without seeing anyone else for days.
They've high-stepped through snake-and-alligator-infested swamps.
But perhaps the most dangerous barrier they've faced so far is man-made: Interstate 4.
This concrete ribbon stretching from Tampa to Daytona Beach is one of the biggest obstacles for wildlife migrating between south and north Florida - for instance, bears.
Daniel Smith, a biologist at the University of Central Florida, joins the group as they get a bear's perspective trying to cross the highway.
"We're five miles northeast of the State Road 44 interchange, going towards Daytona," says Smith. "And we're at the site where one of the large underpasses are going to be built to make Interstate 4 more permeable to black bears and other wildlife."
I-4 was one of the reasons the four travelers decided to walk, bike and kayak the length of the state. Several years ago, researchers - including current expedition member Joe Guthrie - tracked a black bear that roamed much of the central part of the state. He turned back at I-4 when he couldn't find a way across and doubled back to the south.
"The Florida Wildlife Corridor that you're doing right now - that is the major connection between south and north Florida and Georgia," Smith continues. "And so it's critical, as more development incurs - and chokes that off - we need our roadways that are obstructions to that corridor to be highly permeable - they need to be landscape-level connections. And so we need functional, multi-use crossings that allow all wildlife to pass through."
Smith says the money is already there to build a series of underpasses under Interstate 4. The plans were spurred by a study by the Florida Fish and Wildlife Conservation Commission, which was concerned about black bears trying to cross I-4 and getting into accidents with cars.
" The road will be widened from four lanes to six lanes, so the road itself will be wider, but we'll have three of these large underpasses in this section between DeLand and Daytona Beach, and the bridges will be landscaped with natural native vegetation, similar to what's in the habitat on adjacent sides of the road," Smith says, "and there will be fencing associated with the crossings as well to direct the animals toward them."
And with an average of 50,000 cars a day on this stretch of the highway, it's not an easy place to cross for humans, either. Expedition filmmaker Elam Stoltzfus says they found a spot where a bear appeared to break part of the fencing along the Interstate.
"We walk up to the edge and get ready to cross over the main highway, and we stay there and we wait and look and (makes car sounds) and it must've been three, four minutes before we could cross over" says Stoltzfus. "Of course, that's only half way - we're in the median. So I have to come back and get the camera, reset and eventually we get all the way across. So I can't imagine what it would be like if you were a bear or panther - I'm sure you would just give up or get killed - you know, you'd get hit."
Smith says there's only one other place along I-4 where a wildlife underpass is also being considered: near Lakeland, to connect the Green Swamp with the Peace River headwaters.
This section of highway in Volusia County is considered ideal for a wildlife corridor. It's girded on one side by the Tiger Bay State Forest; on the other side by an area set aside to protect a city water wellfield. Cathy Lowenstein with the state Department of Forestry was also on hand for the crossing.
"Our two forests are part of the corridor that connects this coastal strip of flatwoods that's very important to the statewide corridor over to the Ocala National Forest in the central part of Florida," she says. "So it's a very important linchpin here in Tiger Bay State Forest to corner over and go over toward Ocala National Forest, where the bear-roaming habitat can extend so much from the center of the state - where it's large - over to the coastal areas."
The group is hoping to raise awareness for more wildlife crossings under busy roads. In a couple of weeks, they'll get an up-close look at the next major man-made barrier they'll have to cross - Interstate 10.
Michelle Walker of WFIT Public Radio in Melbourne contributed to this report.
