They didn't stay around long, but the eight lady cougars from Texas who temporarily set up housekeeping in southwest Florida in the late 1990s left a lasting impression.

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They didn’t stay around long, but the eight lady cougars from Texas who temporarily set up housekeeping in southwest Florida in the late 1990s left a lasting impression.

Their genes may have saved from extinction, for now, Florida’s last remaining panthers by bringing fresh blood into a dwindling, inbred population, according to research being published Friday in the journal Science.

“Once they got in, they didn’t waste much time,” said Stephen O’Brien, chief of the Laboratory of Genomic Diversity at the National Cancer Institute in Frederick, Md., who helped lead the study and has worked on the restoration project for decades. “Now every panther in Florida has an ancestor from Texas.”

Whether they’re called a panther, cougar, puma, mountain lion or catamount, all of North America’s big cats share the same roots: a small group of Central American panthers that moved into the continent at the end of the last ice age, scientists say.

They differ only slightly according to habitat, and subspecies regularly mingled in border areas. So, while the Texas females arrived in Florida with human help in 1995, ancestors of the two groups had mated regularly in the vicinity of Louisiana before the two populations were cut off in the 19th century, researchers said.

That isolation and loss of habitat had reduced Florida’s panthers — the last population east of the Mississippi River — to 20 to 30 mostly geriatric individuals before the restoration project began.

Texas wildlife biologist Roy McBride, a co-author of the study, has been tracking cougars in his home state and Florida for decades. A female — captured in a tree by McBride and his dogs west of Lake Okeechobee in 1973 — was the first scientific proof in decades that the subspecies hadn’t gone extinct. But the survivors were a sad lot.

“They were doing real poorly,” McBride said. “They weren’t having many kittens, and they weren’t raising a lot of the kittens they did have.”

There are now about 100 mature panthers and 20 to 30 kittens roaming the Big Cypress Swamp and surrounding areas. “That’s quite a few, although well short of the 500 or 1,000 you’d like to see for a sustainable population long term,” O’Brien said.

Gone from the population are most of the genetic flaws that plagued the few dozen bedraggled panthers wildlife experts found in the swamp in the mid-1990s: heart defects, kinked tails, high loads of parasites, low testosterone levels and, crucially, poor sperm quality, undeveloped testicles and low reproductive rates.

The newer generation of big cats is stronger, faster and more prolific. McBride, whose team also rounded up the Texas imports, told his colleagues the reinvigorated breed has become harder to catch. Panthers sometimes leap from trees over dogs and humans alike to escape, something earlier generations never did.

Biologists decided to shut down the breeding experiment in 2003, recapturing the surviving two Texas females to live out their days at a research station in north Florida and shutting off the dilution of the gene pool.

Researchers caution that, while the Florida panthers have won some genetic breathing room, they’re not safe. “We’ve slowed down the loss of genetic variation, but if they remain isolated the problems will return,” said David Onorato, a research scientist with the Florida Fish and Wildlife Conservation Commission’s research institute in Naples, Fla.

“It really all comes down to giving them the habitat to expand and increase to larger numbers and range.”