All Intensive Purposes

Closing the barn door after the Burmese pythons are loose:

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. . . .

“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, pied-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.”

And they're hard to find:

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.

But wait, there'll be more:

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.”