Cold Snap Killed Many Pythons In Everglades

Interesting article in the Sun Sentinel last week:

By David Fleshler and Lisa J. Huriash - Updated: 02/14/2010 12:02:47 AM EST

FORT LAUDERDALE, Fla. - Vultures circled over Everglades National Park's Anhinga Trail, where thousands of dead non-native fish floated in the marshes.

About half the Burmese pythons found in the park in the past few weeks were dead.

Dead iguanas have dropped from trees onto patios across South Florida. And in western Miami-Dade County, three African rock pythons - powerful constrictors that can kill people - have turned up dead.

Although South Florida's warm, moist climate has nurtured a vast range of non-native plants and animals, a cold snap last month reminded these unwanted guests they're not in Burma or Ecuador any more.

Temperatures that dropped into the 30s killed Burmese pythons, iguanas and other marquee names in the state's invasive species zoo.

Although reports so far say the cold has not eliminated any of them, it has sharply reduced their numbers, which some say may indicate South Florida is not as welcoming to invaders as originally thought.

"Anecdotally, we might have lost maybe half of the pythons out there to the cold," said Scott Hardin, the Florida Fish and Wildlife Conservation Commission's exotic species coordinator. "Iguanas definitely. From a collection of observations from people, more than 50 percent fatality on green iguanas. Green iguanas really got hit hard. Lots of freshwater fish died; no way to estimate that."

The cold snap has played into a highly politicized debate over how to prevent non-native species from colonizing the United States. Reptile dealers and hobbyists strongly oppose a proposal by the U.S. Fish and Wildlife Service to ban the import of and interstate trade in Burmese pythons and several other large snakes. They say South Florida's cold snap shows these species don't threaten to spread north, as some claim, and a federal crackdown is unnecessary. "

Pythons are tropical animals," said Andrew Wyatt, president of the United States Association of Reptile Keepers. "When temperatures fall below a certain level, they are unable to survive. It reinforces the idea that the pythons can't exist more than a short period of time north of Lake Okeechobee. Even the pythons in the Everglades are dying during the cold snap."

Wyatt said scientists are downplaying the effect of cold weather on the pythons because that would undermine their ability to win grants to study a problem that has received international publicity.

"It's all about money," he said. "It's very little to do with the truth of fundamental problems on the ground."

But federal and state wildlife officials say the cold weather has not solved the problem. Not only did pythons survive, but so did other invasive species, even if the cold set them back a bit.

Along the park's Gulf Coast, where old-world climbing ferns lay dense mats over native trees, the cold snap inflicted frost damage on these invaders from Asia and Australia, said David Hallac, chief biologist at Everglades National Park. But it didn't kill them, he said, and they continue to spread.

And although they receive less publicity than pythons, non-native fish have infested the Everglades. The cold weather apparently killed them in the thousands, including the Mayan cichlid, walking catfish and spotfin spiny eel, Hallac said. But at the bottom of canals and other water bodies, pockets of warm water allowed some of these fish to survive, he said, giving them a chance to repopulate the park once the weather warms up.

No one knows how many Burmese pythons live in the Everglades, where they were released as unwanted pets or where they found refuge after hurricanes destroyed their breeding facilities. But what's certain is there are a lot fewer today than there was a month ago.

Greg Graziani, a police officer who owns a reptile breeding facility, is one of several licensed python hunters who stalk the snakes in the Everglades. In four days of snake hunting, he found two dead snakes, two live ones, and one snake on the verge of death.

"Vultures had pecked through 12 inches by 4 inches down the back of this animal's body," he said. "I thought it was dead and we reached down to pick it up and it was very much alive."

In cold weather, Graziani said, pythons go into a catatonic state, and if they don't make it to a safe place to ride out the weather, freeze to death. "We're finding the smaller pythons are handling it better than the large ones - the smaller ones can get into different cracks and crevices to maintain the temperatures they need."

Joe Wasilewski, a wildlife biologist who hunts pythons in the Everglades, said on a single day in late January he found seven live snakes and seven dead ones. "

You don't see dead ones like that for no reason," he said. "And they were laid out like they were caught by the onslaught of the cold, the way the carcasses were lined up."