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."

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