Florida panther clawing back but deaths, shrinking land remain concerns
By Eric Staats
November 16, 2012
An endangered Florida panther lying dead on the side of the road after getting hit by a car or truck can be a grisly sight.
Almost everybody can agree on that.
Some panther advocates and panther scientists don't agree, though, on the impact of the road death tally on the wildcats' overall population health.
Panthers have been steadily clawing their way back from the edge of extinction since the 1990s, but that good news has been tempered by a rise in the number of panthers killed on Southwest Florida roads and killed in the wilds in fights with other panthers over shrinking territory.
The Florida Fish and Wildlife Conservation Commission chalked up its 13th roadkill panther of the year on Thursday, a 1-year-old female found dead along a stretch of State Road 29 south of Interstate 75 that doesn't have a wildlife underpass.
That brought 2012's total number of reported panther deaths to 21, only four short of the 2007 record, The record year for panther roadkill was 2009, with 18.
The 2012 death tally also includes six panthers killed in fights with other panthers, the third time in the past decade the level of what scientists call intraspecific aggression has climbed that high.
Don't panic, says Conservation Commission panther team leader Darrell Land. He said the higher mortality numbers are to be expected in a growing population.
"We're not alarmed by the numbers," Land said. "I'm not real concerned that these higher mortalities in recent years are going to cause the population to decline any time soon."
Scientists say as many as 160 panthers, up from as few as 30, thanks to a decision to move female Texas cougars to Southwest Florida to boost the gene pool and produce healthier offspring. Now, though, the expanding population is running out of room in Southwest Florida,
Wildlife biologists call it the S curve, the classic shape of a line graph charting a wildlife population as it rapidly bounces back and then flattens out.
"It looks like we're starting to see that (with panthers)," said Larry Williams, the U.S. Fish and Wildlife field supervisor in South Florida.
Some panther advocates, though, are skeptical of such back-of-the-cocktail napkin calculations.
"It's almost like the panther is becoming the parable of the loaves and fishes," said Jeff Ruch, executive director of Public Employees for Environmental Responsibility, a nonprofit whistleblower protection group based in Washington, D.C. "It can keep giving without ever running out."
In 2004, PEER represented former U.S. Fish and Wildlife Service biologist Andy Eller in an unsuccessful attempt to get his job back after he questioned the science his agency was using to approve development in panther habitat and was fired.
Land, at the Conservation Commission, said panthers are producing enough kittens each year to keep up with recent mortality trends, with births by females with radio tracking collars reaching 38 so far this year.
Kitten survival rates can be as low as 30 percent, but most females aren't tracked, about half the population is female and the average litter is between two and three kittens, Land said.
"The numbers still work out in their favor," he said.
Land said the agency is trying to find a better way to count panthers to make the calculation less of an educated guess.
"We haven't found that magic technique yet, but we're still looking," Land said.
Southwest Florida panther advocates say they agree that kitten births are keeping up with panther deaths, but say the roadkill toll should lend new urgency to action to keep the numbers of dead panthers to a minimum.
Florida Wildlife Federation field representative Nancy Payton has pushed for making more road segments safer by building widlife crossings under them at spots where panthers like to travel.
"Don't mourn, build underpasses," she said.
Conservancy of Southwest Florida President Andrew McElwaine said panthers need more habitat protection to avoid population declines that would turn the S curve upside down.
"The more habitats we lose, the worse it's going to get," he said.