Exotic pythons have Florida Everglades in their stranglehold

By Lukas Ondreka Feb 27, 2012, 9:45 GMT

Washington - A five-metre constrictor cheerfully swallowing a 25-kilogram deer has become a relatively common sight in the Florida Everglades. The hungry snakes - intruders from the jungles of southern Asia - have been eating their way across the swamps since 2000.

The Burmese python are devastating this important conservation area and other parts of the Sunshine State, according to a new scientific study published in the Proceedings of the National Academy of Sciences.

Some 99 per cent of the raccoons, almost as high a proportion of the opossums and 88 per cent of the indigenous bobcats have disappeared from the habitat, according to the study, which claims to be the first that shows definitively that the snakes are the prime cause.

'Pythons are wreaking havoc on one of America's most beautiful, treasured and naturally bountiful ecosystems,' US Geological Survey (USGS) Director Marcia McNutt says. 'Right now, the only hope to halt further python invasion into new areas is swift, decisive and deliberate human action.'

Human behaviour is definitely to blame for the current situation. The snakes were imported over decades. The pets have turned into pests, after owners released them into the wild when they tired of them or they escaped, many of them following the devastation caused by Hurricane Andrew in 1992. The first pythons were sighted in the 1980s, but since 2000 their number has soared.

Gordon Rodda, USGS specialist for invasive species, is pessimistic on the chances of preventing further spread. There are no case studies showing that exotic species like the Burmese python can be exterminated, he says.

Park rangers have caught or killed more than 1,800 of the huge snakes in the Everglades over the past decade, but this has made little impact. Rodda puts their number at above 10,000. The US administration recently banned the import and all trade in the snakes that can grow to five metres and weigh up to 70 kilograms.

But trade in the Boa constrictor remains legal, as a result of pressure from the US Association of Reptile Keepers (USARK), even though the USGS rates as high the risk that these constrictors could cause serious damage to other ecosystems.

Reptile-keeping is a popular hobby in the United States, with 13 million snakes, lizards and various turtles and tortoises being kept as pets, and the legal trade in reptiles is worth 2 billion dollars a year, according to the Humane Society, an animal protection group.

These factors make a ban on the trade extremely unlikely. The illegal trade could reach an astonishing 3 billion dollars, according to the Humane Society.

Ten scientists spent nine years gathering data on the Everglades, covering 63,000 kilometres across the spectacular swamps to collect information on everything that walked and crawled and comparing it with similar studies dating back to 1996 and 1997.

They found that the invasion of the pythons was endangering even large reptiles like alligators, and the indigenous Florida panther could become extinct.

Worse could be yet to come. Surveys from 2008 indicate the snakes could spread across large swaths of the southern United States. Individual specimens have been found on the Florida Keys, the chain of islands off the coast of the mainland.

They are easier to catch on the islands, given the limited space for them to escape. A northward migration would be much more difficult to stop. 'We have no options available for stopping the spread of the snakes into the Florida interior,' Rodda says.