A Movable Beast - Pythons thrive in Florida

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EVERGLADES NATIONAL PARK, Fla. — Skip Snow, a federal biologist in Everglades National Park, would love to spend his days monitoring the dizzying array of native wildlife across this 1.5-million-acre “river of grass” west of the ever-expanding Miami metropolis.

Lately, however, he has been spending ever more time studying the remains of the park’s birds and animals, extracted from the stomachs of captured or road-killed Burmese pythons, the latest — and most spectacular — addition to Florida’s growing list of biological interlopers.

Opening a packed freezer in a park laboratory, Mr. Snow sifted dated plastic bags containing fur, feathers, bones and other vestiges of recent python prey.

“We’ve found everything, from very small mammals — native cotton mice, native cotton rats, rabbits, squirrels, possums, raccoons, even a bobcat, most recently the hooves of a deer,” Mr. Snow said. “Wading birds and water birds, pipe-billed grebes, coots, egrets, limpkins and at least one big alligator.”

The South Asian snakes, which can top 200 pounds and 20 feet, probably entered the park as discards or escapees from the bustling global trade in exotic pets. Year-old, footlong pythons are a popular $70 item at reptile fairs and on the Web but in a few years can reach room-spanning, cat-munching size, prompting some owners to abandon them by the roadside. That practice may not pose an ecological problem in Detroit, Mr. Snow said, but in a near-tropical Florida park, it is an unfolding nightmare.

Some very rough estimates put the state’s pet python population above 5,000. More than 350 have been found in the park since 2002, with others showing up in mangroves along Florida’s west coast and farther north in the state. There are perhaps 10 more for every one that is seen, Mr. Snow said.

In May 2006, biologists confirmed that Everglades pythons were not a transient curiosity when they found the first eggs. “There were 46 eggs, 44 fertile,” Mr. Snow said. Shortly afterward, they found another clutch of two dozen, already hatched.

Signs abound, he said, that the pythons are still colonizing new terrain. “This is a species that is really made for invading.”

Mr. Snow and other wildlife biologists have been on something of a crusade of late, pressing federal and state governments to crack down on the trade in such species, quicken responses when an invader appears in the wild and expand federal preventive screening to identify — ahead of time — imported animals and plants that are most apt to spread in this country.

While there is a National Invasive Species Council whose membership includes cabinet-level officials, the grunt work of preventive species screening is done by a handful of biologists at the Fish and Wildlife Service, the Department of Agriculture and the Department of Health and Human Services.

The vast majority of the $1 billion or so the government spends each year on invasive species goes to managing existing problems, with about 10 percent, according to a recent government report, going to prevention. In the meantime, the government estimates that invasive species cost the economy $100 billion a year.

The python may be a marquee-quality “spokes-snake” for invasive species, Mr. Snow said, but it is hardly alone in its potential to disrupt ecosystems and pose a possible threat to people and the economy once established. Along with hundreds of accidental immigrants like zebra mussels, there have been innumerable intentionally imported plants and animals that have become vexing, expensive problems. Once they are noticed, it is almost always too late, or too costly, to eradicate them, experts say.

Still, such species tend to become a priority only after the fact, biologists say. It was not until this year that a new Florida law established a list of six “reptiles of concern” (including the python). The state will soon require $100-a-year owners’ permits and the insertion of identifying microchips under the skin of the purchased pets.

This year, the South Florida Water Management District petitioned the federal Fish and Wildlife Service to add Burmese pythons to a list of “injurious wildlife” maintained under the 107-year-old Lacey Act.

Kari Duncan, the director of the service’s invasive species program, said it could take a while to make that determination. There is only one federal biologist, Erin Williams, whose job is to do such assessments, and she is already stacked up with years of work, mainly on fast-spreading carp and other aquatic species, Ms. Duncan said.

In the meantime, the workload has grown. In a 2002 executive order, the Bush administration added a requirement that potential economic effects to small businesses and the like from such listings be studied. Adding to the challenge, Ms. Duncan said, is that the tiny budget for the screening program, essentially Ms. Williams’s salary, must be fought for year by year.

One sign of progress, of a sort, Ms. Duncan said, is that “this was just 1/32 of a job a few years ago.

The reviews are bogging down even as the accelerating globalization of trade and travel has greatly raised the chances of more damaging invasions, experts say. The species are flowing in all directions, with American bullfrogs overrunning local amphibians in France, and Louisiana crayfish spreading in Chinese streams even as Asian snakehead fish advance here.

“This pipeline, it’s almost equivalent to a large Russian roulette game,” Mr. Snow said. “We’re firing this tremendous number of animals, not only individual species, but tremendous quantities of each, coming in the country. As a general rule of thumb, 50 percent of those invasive plants and animals that sort of get out will establish, will be able to reproduce, and about 50 percent of those will spread. We just continue to fire away and never knowing which one is going to be the next Burmese python.”

David M. Lodge, the director of the Center for Aquatic Conservation at the University of Notre Dame, has been an author on a series of recent studies of the issue, including a position paper last year from the Ecological Society of America pressing for much stronger federal investment and action.

“When it comes to importing live organisms, our policies are entirely reactive,” Dr. Lodge said. “It’s as if in the drug realm we were to allow any new drug or food product on the market until it kills someone and then consider a regulation to ban it.”

With invasive species, though, the situation is actually potentially worse, he said, because banning them after the fact does not eliminate the threat.

As Mr. Snow put it, “Invasives are the gift that keeps on giving, because of the biological imperative to reproduce.”

The benefits of action greatly outweigh the costs, Dr. Lodge said, citing the example of Australia’s system for screening imported ornamental plants, with swift initial assessments usually taking just one week.

Lori Williams, the executive director of the federal invasive species council, said Florida’s growing focus on snakes and other terrestrial introduced species could raise the profile of the issue in Congress.

Like many preventive efforts, she said, fighting introduced species is a tough sell in the arena of politics. “This is one of those problems you don’t tend to see until it’s already out there, that kind of sneaks up on you,” Ms. Williams said. “It’s also not a terribly fun, sexy problem because you have to go out and kill things to solve it.”

Mr. Snow, while eager for more prevention, is also spending time in the field eradicating whatever pythons can be found.

One method is to turn the python’s biology against it. It appears that males seek females in the spring by following scent trails, so park biologists, along with other scientists, are testing whether females — with radio transmitters inserted into their body cavities — can serve as “Judas snakes,” a living lure for mate-seeking males.

The tags are also helping park biologists get a sense of individual snake’s habits amid the miles of saw grass, brush-studded “hammocks,” old wooded levees and sloughs.

On a recent checkup on several tagged females, Mr. Snow and Lori Oberhofer, another park biologist, headed out in Mr. Snow’s battered, white S.U.V. with a beeping radio-tracking receiver and “Python Pete,” a beagle trained to sniff out pythons.

The challenge of extirpating such snakes in such a vast place becomes clear up close. Even when the beeps and snuffling dog indicated that a 10-foot python was between Mr. Snow and a reporter 15 feet away, the animal could not be located for a couple of minutes — until it slid directly past the reporter’s soggy shoes.

While Mr. Snow is hunting whatever pythons he can find and pushing for new laws and more money for preventive programs, he is also working at the grass-roots level.

In frequent slide presentations to community groups, he pulls no punches, describing how the snakes seize prey with small sharp teeth and suffocate it with muscular coils. There are several recorded deaths of pet owners in the United States strangled or suffocated by pythons.

One slide says: “Do you really want a snake that may grow more than 20 feet long or weigh 200 pounds, urinate and defecate like a horse, live more than 25 years and for whom you will have to kill mice, rats and, eventually, rabbits?”

But the appeal of the snakes persists in the pet trade, which has seen the number of households with a reptile pet climb to nearly 5 million from fewer than 2.8 million through much of the 1990s, according to industry surveys.

Despite his focus on pythons, Mr. Snow’s greatest worry remains the next species down the line, whatever that may be.

Amid the bags of frozen biological items back in the park laboratory was a coiled eight-foot-long yellow-bellied snake that Mr. Snow received in January. A forestry crew in Big Cypress National Preserve had stumbled on the animal, he said. “They assumed it was a python, but when I looked at it and saw it had nostrils on top of its head, I said, ‘Oops, this is no python.’ ”

It was a yellow anaconda, from South America, not South Asia.

“Is this one individual or a population?” he mused. “Do we put a moratorium on sales or do nothing? Is it the new kid on the block? We don’t know yet.”

http://www.nytimes.com/2007/07/24/sc...ewanted=2&_r=1