MIAMI Burmese pythons and other giant snakes imported as pets could endanger some of America's most important parks and wilderness areas if they are allowed to multiply, according to a report released on Tuesday.
Wildlife experts say the Burmese python is distributed across thousands of square miles in south Florida. There could be tens of thousands in the Everglades, a wildlife refuge that is home to the Florida panther and other endangered species.
The Burmese python and four other non-native snakes -- boa constrictors, yellow anacondas, northern and southern African pythons -- are considered "high-risk" threats to the health of U.S. ecosystems because they eat native birds and animals, the U.S. Geological Survey report said.
Two species, the boa constrictor and Burmese python, have already established breeding populations in south Florida and experts have found "strong evidence" that the northern African python may be breeding in the wild as well.
Four other snakes, the reticulated python, green anaconda, Beni anaconda and Deschauensee's anaconda, are considered "medium-risk" but are still potentially serious threats, the USGS report said.
Florida wildlife officials say the Everglades wetland is a dumping ground for pet owners who find their snakes too large to handle when they mature. They eat birds, reptiles, rodents and other small mammals and are considered a major threat to endangered species like the wood stork and Key Largo woodrat.
"This report clearly reveals that these giant snakes threaten to destabilize some of our most precious ecosystems and parks, primarily through predation on vulnerable native species," Robert Reed, a USGS invasive species scientist, said in a statement.
The snakes are among the largest in the world. Three of the nine species can reach lengths of 20 feet (6 metres) and weigh more than 200 pounds (90 kg), the report said.
The reticulated python is the world's longest snake and the green anaconda is the heaviest, the scientists said, and both have been found in south Florida, although it was not certain if they are breeding.
Some of the snakes, including the boa constrictor and northern African python, are tolerant of urban living and already live wild in the Miami suburbs, the report said.
Scientists said the threat to humans from giant snakes in the wild is small.
A 2-year-old Florida girl was strangled this summer by a pet Burmese python that escaped from a holding tank in the child's home.
State wildlife managers recently allowed hunters to kill invasive snakes. Legislation has been introduced in the U.S. Congress to ban the importation of some constrictors and the Humane Society of the United States recently said it supported laws to stop the importation of and trade in large reptiles.