NAPLES — Cattle rancher Russell Priddy knew panthers roam his cow pastures south of Immokalee.
He had never tried to count them, but he and his wife, Liesa, started counting calves as they went missing from their JB Ranch last fall.
The Florida Fish and Wildlife Conservation Commission confirmed at least two of the Priddys’ calves and one on a neighboring pasture were killed by panthers and dispatched trackers to the Priddys’ 9,000-acre ranch to try to get a handle on the problem.
Over six days in November, the team combed 3,000 acres southeast of Oil Well Road and State Road 29 and treed nine panthers, according to the trackers’ report to the Conservation Commission.
“That number surprised even me,” Priddy said.
Trackers said at least one of the panthers might have been counted twice, but the discovery added fuel to the debate about whether the Conservation Commission has been undercounting the number of endangered panthers in South Florida, their last holdout.
Now, in a “Statement on Estimating Panther Population Size” quietly released last week, the Conservation Commission has put a new number on the books _ 163.
State biologists say that is the upper limit of the panther’s population range, replacing the old estimate of 100 to 120 panthers.
In the carefully worded statement, the Conservation Commission said the new number doesn’t represent a sudden jump in the number of panthers and that the range of 100 to 120 panthers was always meant to be a minimum estimate.
Livestock protection from panthers in Golden Gate Estates
That’s not how it’s always been understood, though, including in the U.S. Fish and Wildlife Service’s official recovery plan for the panther. That plan, updated in 2008, uses the estimate of 100 to 120 panthers in several places but doesn’t hedge it as only a minimum.
The Conservation Commission has been working on the new estimate for about a year — before last year’s reports of panthers killing calves — in response to calls for a more accurate panther count, said Kipp Frohlich, imperiled species coordinator for the Conservation Commission.
“By providing only the minimum number, it kind of leaves the question open,” he said. “I don’t expect the debates to subside, but maybe they’ll be better informed with this.”
Still, he called the new estimate little more than a “mathematical theoretical exercise.”
It was derived by figuring how many panthers had been counted in 2009 in the Big Cypress National Preserve, the Fakahatchee Strand Preserve State Park, Picayune Strand State Forest, Florida Panther National Wildlife Refuge and the Big Cypress Seminole Indian Reservation.
That came to 58 panthers over about 1,300 square miles. The Conservation Commission then applied that ratio to the larger primary panther zone to come up with 163 panthers.
The upper estimate “is based on the idealized and unlikely premise” that panthers are evenly distributed even though panther habitat varies by type and quality, the statement said.
The statement also admits that counting panthers isn’t a perfect science and that techniques can miss panthers or double-count them.
“I think their new estimate is very much on the low side,” Priddy said.
The Conservation Commission is looking at other ways to get a better estimate of the panther population.
One method would use trail cameras, but there are questions about whether that would create scientifically reliable estimates, Frohlich said.
Biologists also are working with statisticians to try to develop a model that would estimate the panther population based on the number of dead panthers found with tracking collars.
About 25 percent of the panthers’ range is on private lands, like the Priddys’ ranch, that aren’t surveyed by the annual count used to figure the new upper estimate.
Frohlich said the Conservation Commission is preparing research proposals to present to landowners in hopes of gaining access to more private lands to capture panthers and put tracking collars on them.
The Conservation Commission and Big Cypress National Preserve monitor 23 panthers with tracking collars, but that number could grow to 30 or so by the time teams have completed this winter’s panther capture season on public lands, Conservation Commission panther team leader Darrell Land said.
For Priddy, the panthers on the JB Ranch are a source of pride in his stewardship — to a point.
He estimates that panthers have dragged off at least 35 of his calves. The true toll won’t be known until he gathers up his calves to take to market in April.
Frohlich had a first meeting Friday in Collier County with a working group of landowners and conservation groups to discuss options for stemming panther predation and compensating landowners for calves that are killed by panthers.
“I certainly don’t mind them being there,” Priddy said. “But I can’t be put out of business from feeding them.”
Connect with Eric Staats at www.naplesnews.com/staff/eric_staats