GAINESVILLE, Fla. (AP) - The endangered Florida panther may have been pulled back from the brink of extinction, but its growing population is running out of room to roam.
Breeding programs with the Florida panther's imported cousin, the Texas puma, have helped to revive the population from a low of around 30 two decades ago to an estimated 140 today.
The panther population isn't out of the woods yet, but with those numbers rebounding, efforts to save the tawny predator have shifted focus to preserving what remains of their existing habitat in Southwest Florida and looking at opening new areas further north.
"Habitat management and road structures to limit mortality are the next step," said Jeff Hostetler, a scientist at the Smithsonian Institution who did research on efforts to revive the Florida panther population while he was a graduate student at the University of Florida.
In a paper published in the Journal of Animal Ecology last year, Hostetler and his colleagues showed how introducing the Texas puma into the Florida panther population succeeded in saving the population from extinction - at least temporarily.
Their paper was runner-up for the Elton Prize in Ecology, awarded by the British Ecological Society each year.
"A Cat's Tale: The Impact of Genetic Restoration on Florida Panther Population Dynamics and Persistence" shows the success of the genetic restoration efforts in 1995, when eight female Texas pumas were released into Florida panther habitat.
The theory was that the more vigorous Texas DNA would mix with the severely inbred stock of the isolated group of Florida panthers and help to eliminate debilitating defects.
The panther population grew by about 4 percent a year, their research showed. Furthermore, they estimated that without the genetic restoration program, the Florida panther population would have shrunk by about 5 percent a year. Without the genetic restoration program, the Florida panther ran a high risk of extinction.
Even so, Hostetler said, scientists estimate there is still a 6 percent chance of extinction over the next 100 years - unless they can prevent further habitat degradation and loss.
Before European settlers came to the southeastern United States several hundred years ago, the Florida panther roamed from the southern tip of the state all the way to the western border of Louisiana where it butts up to Texas.
Those early settlers hunted the animal down, driving it deeper and deeper into the southwestern Everglades around Fort Myers and Naples.
That remaining habitat has been lost to human development. These days the panther is confined to barely enough land and wildlife to support the existing population, scientists say.
There is some buzz being generated about discussions to reintroduce the panthers back into North Florida, said Jaclyn Lopez, staff attorney for the Center for Biological Diversity.
The idea comes with serious concerns - fear of livestock and pets being attacked primary among them, along with the competition with hunters for prey like deer and wild hogs.
"We haven't had big cats this far north in a while," said Lopez, who recently organized and led a symposium on the Florida panther at UF's Levin College of Law.
But research has shown it is possible. Chris Belden, the Florida Panther Recovery coordinator with the U.S. Fish and Wildlife Service, said an experiment in 1993-95 introducing mountain lions into the Okefenokee National Wildlife Refuge was successful. The mountain lions were a proxy for the Florida panther.
The Center for Biological Diversity, which has been involved in panther protection for the last decade or so, is encouraged by the latest developments with the Fish and Wildlife Service's panther management plan.
The goal is to help the panther to reach a state where it is no longer endangered. To do that, there need to be self-sustaining populations outside the South Florida population, Lopez said.
To do that, they have to stop loss, fragmentation and degradation of habitat, she said.
"There is only so much habitat, and what is left is not being well managed," Lopez said.
The obvious is when acres of land are turned into subdivisions - the historic development pattern of South Florida, she said. The dense coastal development pushes the panther farther inland, away from its food source. Recently, a panther was found on the beach near Naples and had to be relocated.
Fragmentation occurs when you build a road through an area, effectively dividing a habitat into two isolated habitats with a busy road that makes it impossible for animals to cross over without risking death.
Degradation may not be as intense or obvious - like mining and oil drilling.
Panthers are pretty adaptable, Lopez said, but the habitat must be contiguous for them to thrive, not fragmented by four-lane roads and other obstacles.
"They are big-time predators that need lots of land with prey and areas for shelter," Lopez said.
The center is currently suing the Army Corps of Engineers, which allows permits for dredging operations.
The center also is working through the administrative process to get the U.S. Fish and Wildlife Service to designate critical habitat for the Florida panther, which would provide an extra layer of protection, she said. When the Florida panther was first listed as endangered, critical habitat designation was a nonexistent concept.
The other thing the center is working on is getting FWS to introduce panthers to the Okefenokee Swamp, something she said has recently become a priority of the Panther Recovery Implementation Team.
"It's a nice chunk of land that we think panthers will actually do well in," she said.
The Panther Recovery Implementation Team will meet in Fort Myers on May 22 to unveil its team priorities, which include habitat expansion, she said.
Without expanding the range of the panther, its population is not likely to grow, said Madelon Van De Kerk, who has taken over Hostetler's research at UF.
"I wouldn't expect to see a whole lot of increase in the size of the population," she said. In fact, about 20 panthers are dying each year, she said.
Using computer modeling, Van De Kerk's research shows that the survival rate is much lower than previously thought for the kittens, aggravated by the habitat destruction and vehicle collisions.
Without expanding the habitat, though, researchers could see a rise in the defects caused by inbreeding again, she said. Already, only about a third of the newborns survive, she said.
"We still have some really big problems," she said.
Solving those problems requires money, and almost all the research into saving the only panther population remaining in the southeastern United States comes from the sale of Florida panther license plates - which dropped from 80,000 tags in 2008 to almost 54,000 in 2013.
"It makes me very happy to see those plates," Van De Kerk said. "Every time I see one, I say thank you."