Texas Cats Help Triple Florida Panther Population

Maryann Mott
for National Geographic News
August 18, 2005
The number of Florida panthers has almost tripled in recent years as the
result of a controversial breeding program aimed at improving their
genetic health, a new research paper reveals.

In 1995 the U.S. Fish and Wildlife Service took eight female panthers from Texas and released them in southern Florida.

Since then the population native to Florida has grown from about 30 to a recent count of 87, says Stuart Pimm, a Duke University professor and National Geographic Committee for Research and Exploration member.

"A lot of scientists said this kind of genetic rescue would not work," the conservation biologist said. "They said if a species is rare and its range is restricted, just adding individuals from the outside is not going to work. Some thought it would be a waste of time, a waste of money."

Pimm collaborated with doctoral student Luke Dollar and Oron "Sonny" Bass, a biologist who has studied panthers at Florida's Everglades National Park for nearly 20 years. The trio collected data before, during, and after the management intervention.

Their study is slated to appear next year in the British journal Animal Conservation.

Hybrid Kittens

After their release, five of the eight Texas panthers went on to produce hybrid kittens with native Florida cats. In 2003 wildlife managers removed the adult Texas cats to reduce native Florida panthers' exposure to outside genetic material.

In all, 118 purebred kittens (offspring of two native Florida panther parents) and 54 hybrid kittens were born. Researchers found that only 13 purebred and 20 hybrid kittens survived to adulthood.

Those cats were fitted with radio collars to track their whereabouts. Pimm and his colleagues monitored how well purebred kittens survived and compared their survival rate to that of hybrid kittens.

The researchers found more than three times as many hybrid kittens reached adulthood than purebreds. According to Pimm, native Florida panthers suffer from an array of genetic abnormalities, including kinked tails, low sperm counts, and heart defects.

"It turns out that purebred kittens don't survive very well," he said. "They die in very high numbers. Once you get new blood [introduced into the area], those defects disappear from the population."

The study team also found that the hybrid cats moved into sections of the Everglades National Park and Big Cypress National Preserve, wild areas in south Forida once thought unsuitable for panthers.

Ninth Life?

Puma Concolor Coryi once roamed across the southeastern United States. But the tawny cats became isolated on the southern tip of Florida more than a century ago.

Hunting, habitat loss, and reduced prey drastically shrank the panther population, landing the animal on the federal government's endangered species list in 1967.

Today federal protection has been extended to the hybrid cats produced in the genetic enrichment program.

Darrell Land of the Florida Fish and Wildlife Conservation Commission in Naples has studied panthers for 20 years. He says he's encouraged by the population increase.

"At least now it looks like we have a technique that we can use to make sure the panthers aren't going to go extinct solely because of genetic pressures," he said. "Now we can focus a lot more attention on trying to preserve as much of a habitat base as we can and perhaps even expand it over time."

Not everyone, though, believes the novel panther program is a conservation success story.

"It's still too early to say whether this rescue, which is really just an increase in numbers, is a result of genetic changes or it's simply the result of a jump-start in reproduction," said David Maehr, an associate professor of conservation biology at the University of Kentucky in Lexington.

Maehr believes the introduction of Texas cats simply occurred at a time of favorable environmental conditions. He said future fluctuations in habitat quality could adversely affect the panther population.

"I think we need to wait a lot longer to allow Mother Nature to tell us how she is going to treat the Everglades in terms of water levels and deer numbers, before we can say this experiment has succeeded or not," he said. "This case study is still an open book, and it's still very much being written."

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