IT SOUNDED like a joke when the news first broke in 2000: giant Burmese pythons were invading the Everglades. But scientists have measured the impact of the arrival of this voracious species and the news is troubling.

In areas where the pythons have established themselves, rabbits and foxes can no longer be found. Sightings of raccoons are down 99 per cent, opossums 98.9 per cent and white-tailed deer 94 per cent, according to a paper published on Monday in the Proceedings of the National Academy of Sciences.

Sticky end ... a dead alligator protrudes from the ruptured mid-section of a four-metre Burmese python. Credit:AP

''What if the stock market had declined that much? Think of the adjectives you'd use for that,'' said Gordon Rodda, an invasive-species specialist with the US Geological Survey, who published research in 2008 showing Burmese pythons could expand across the southern United States.

''Pythons are wreaking havoc on one of America's most beautiful, treasured and naturally bountiful ecosystems,'' the USGS Director, Marcia McNutt, said.