2013年1月15日 星期二

Pythons Attack the Everglades


Pythons Attack the Everglades

An increase of pythons in Florida causes problems for the food chain
FEBRUARY 01, 2012
LYNNE SLADKY—AP
Since 2000, 1,825 Burmese pythons have been caught in and around the Everglades.
Burmese pythons are native to India and parts of Southeast Asia. But they have found a new place to lurk. A study by the Proceedings of the National Academy of Sciences (PNAS) shows that the pythons are now a big threat to parts of Florida, especially the Everglades.
What brought the pythons from thousands of miles away to the Sunshine State? The reptile trade is big business. So many snakes are shipped to Florida to be bought as pets. In fact, the American Pet Products Manufacturers Association says the reptile trade is worth more than two million dollars a year. Over the years, some of the pet pythons have either escaped or were turned loose after they grew too big for their owners to care for. (An average python can be anywhere from 12- to 19-feet long.) Others may have slithered from pet shops during Hurricane Andrew in 1992.
A Burmese python fights with an alligator in the Florida Everglades.
LORI OBERHOFER—NATIONAL PARK SERVICE/AP
A Burmese python fights with an alligator in the Florida Everglades.
Now, in a hunt for food, they are wiping out native species including raccoons, opossums, bobcats and other mammals in the Everglades. According to the PNAS study, in areas where pythons are present, sightings of medium-sized mammals are down as much as 99%. Researchers found a large decrease in the small mammals that are part of a python’s diet. They also found there were more of those mammals living in areas without any pythons.
In January, U.S. Interior Secretary Ken Salazar announced a federal ban on the import of Burmese pythons and three other species of snakes to the United States. On Monday, he said that the recent PNAS report shows why the ban was needed.
“The study paints a picture of the real damage that Burmese pythons are causing to native wildlife and the Florida economy,” Salazar said. Some snakes, including the boa constrictor, are still allowed to be imported.
A New Predator
Pythons thrive in the warm, humid climate of the Everglades. But a U.S. Fish and Wildlife Service report found that the huge snakes are learning to adapt to colder climates too. This will allow them to spread to other areas.
In January, U.S. Interior Secretary Ken Salazar announced a federal ban on the import of Burmese pythons to the United States.
ALAN DIAZ—AP
In January, U.S. Interior Secretary Ken Salazar announced a federal ban on the import of Burmese pythons to the United States.
The increase in pythons is causing a huge problem for local officials protecting endangered animals. Michael Dorcas is a researcher who worked on the PNAS study. He says pythons are a new top predator—enemy—and shouldn’t be in the Everglades.
“We have documented pythons eating alligators, and alligators eating pythons,” he said. “It depends on who is biggest during the encounter.”
Snake Census
Since 2000, the National Park Service has counted 1,825 Burmese pythons that have been caught in and around the Everglades. Among the largest was a 156-pound, 16.4-foot python captured last month.
Experts fear the pythons will continue to disrupt the food chain and upset the Everglades’ delicate environmental balance. Even though wildlife officials have tried to remove the snakes in the past, they say the population is now too big to be controlled. The problem could become worse as the snakes continue to breed and multiply. 

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