Tuesday, January 31, 2012

Predatory pythons shift Everglades ecology

Janet Raloff in Science News: Giant snakes are eating their way through the Everglades, leaving a drastically changed ecosystem in their wake, a new study shows.

The snakes, many of which measure 10 to 16 feet, are called Burmese pythons. But make no mistake: Virtually all of the roughly 30,000 living in southern Florida were born in the Everglades. Ecologists now report that populations of mammals have begun plummeting throughout the pythons’ expanding range. And the timing of these mammal losses matches the geographic spread of the snakes, which federal officials believe were initially released into the wild by snake fanciers, probably 15 to 30 years ago.

Raccoons, opossums, deer and other mammals, along with birds and gators, have all turned up in the stomachs of captured pythons, testifying to the snakes’ varied appetite, notes ecologist Michael Dorcas of Davidson College in North Carolina. “But until now, there hadn’t been any indication that the snakes were altering the ecosystem,” says Dorcas, who led the study.

The new data “make a persuasive case for cause and effect,” says herpetologist J. Whitfield Gibbons of the Savannah River Ecology Lab in Aiken, S.C., who was not affiliated with the new analysis. “The investigators take a convincing position that introduced predatory pythons are responsible for the decline in numbers of large- and medium-size mammals in the Everglades.”...

University of Florida scientists show off a 15-foot Burmese python, weighing more than 160 pounds, that was captured in the Everglades. Its stomach contained a 6-foot gator. Credit: Michael R. Rochford, University of Florida

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