Invasive Pythons Squeezing Florida Everglades

Maryann Mott
for National Geographic News
October 28, 2005
For decades pet Burmese pythons have been dumped illegally in Florida's
Everglades National Park.

As pets, Burmese pythons are easy to find and cheap to buy. Many pet stores in Florida sell the popular, docile snakes. At reptile trade shows they sell for as little as $20 (U.S.).

Last year 6,140 Burmese pythons were imported into the U.S. from their native homes in Southeast Asia, according to the U.S. Fish and Wildlife Service (FWS). Thousands more were captive bred in the country.

Now hundreds of the constrictors—which reach upwards of 19 feet (6 meters) and 200 pounds (91 kilograms)—are breeding and expanding their range in Florida wetlands.

"These [snakes] are now the huge apex predator in the Everglades," said Kenneth Krysko, a reptile researcher with the Florida Museum of Natural History in Gainesville. "There's nothing bigger."

Human Prey?

The massive snakes potentially pose a threat to human safety.

"Pythons don't go out and search for humans. But as a sit-and-wait predator they certainly can kill one—and certainly wouldn't hesitate if [a human] got in their way," Krysko said.

The first python was discovered in the Everglades in 1979. It was removed, and no more were found until 1995.

In the last four years, though, the population has exploded. More than 230 pythons have been discovered inside the park, Krysko said. The biggest one measured 15 feet (5 meters) long.

Last October an employee of the South Florida Water Management District found five pythons—each eight to ten feet (two to three meters) long—in one day while mowing grass adjacent to the park.

The python's population boom has the Florida Fish and Wildlife Conservation Commission (FWC) worried.

The state agency's law enforcement division recently authorized its officers to kill exotic reptiles, specifically pythons, found on lands under its management, said Kevin Enge, a scientist with the commission.

"When you release [pet pythons] into a wild area like that, they're able to find sufficient things such as food, water, shelter," Krysko said. "And of course it was only a matter of time before they found mates."

Young pythons with umbilical cord scars have been captured, he said, proving the former pets now breed in the wild.

In December scientists plan to capture and tag several pythons with radio-tracking devices to reveal their exact whereabouts inside the 1.5-million-acre (600,000-hectare) national park.

Enge said he just approved a permit for the park service to release these captured pythons back into the wild—something that is normally illegal to do.

"Hopefully that information will enable [park operators] to better determine where to catch pythons in the future," Enge said. "Then, once they've got that information, they'll euthanize the pythons."

Invasive Impact

Wildlife experts say it's too early to tell what, if any, impact the snakes are having on native Everglades species.

But there is some worry the pythons may start feeding on birds, such as limpkins, which are not accustomed to defending themselves against nocturnal predators.

"Burmese pythons in their native range have been known to hang around wading bird roosts and prey on them at night by climbing up [trees] and getting them," Enge said.

Stomach contents of captured and road-kill pythons have shown they frequently eat small mammals, such as rabbits, raccoons, grey squirrels, and possums.

The monster constrictors can also squeeze the life out much larger prey before swallowing it whole. Earlier this month a 13-foot (4-meter) python tried eating a 6-foot (2-meter) alligator. (See "Photo in the News: Python Bursts After Eating Gator.")

The sizable meal proved too much for the snake, though. The partially digested alligator was found protruding from the dead python's ruptured gut.

The Fish and Wildlife Commission is now considering tightening regulations to stem the flow of illegally abandoned and escaped constrictors.

Possibilities include requiring owners to obtain a U.S. $140-per-year permit and implanting pythons with identification microchips, Enge said.

In the meantime FWC is encouraging pet shops to take back unwanted snakes previously purchased from them.

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