Skip Snow, a federal biologist in Everglades National Park, would love to spend his days monitoring the dizzying array of native wildlife across this 607,000-hectare "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, 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," 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 90kg and 6m, probably entered the park as discards or escapees from the bustling global trade in exotic pets. Year-old, 30cm-long pythons are a popular US$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, 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, Snow said.
Last May, biologists confirmed that Everglades pythons were not a transient curiosity when they found the first eggs. "There were 46 eggs, 44 fertile," 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."
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 US$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 US$100 billion a year.
The python may be a marquee-quality "spokes-snake" for invasive species, Snow said, but it is hardly alone in its potential - once established - to disrupt ecosystems and pose a possible threat to people and the economy. 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.
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