The study, published Monday in the Proceedings of the National Academy of Sciences, found that sightings of medium-size mammals are down dramatically - as much as 99 percent, in some cases - in areas where pythons and other large, nonnative constrictor snakes are known to be lurking.
Scientists fear the pythons could disrupt the food chain and upset the Everglades' environmental balance in ways difficult to predict.
"The effects of declining mammal populations on the overall Everglades ecosystem, which extends well beyond the national park boundariesh, are likely profound," said John Willson, a scientist at Virginia Tech University and co-author of the study.
Tens of thousands of Burmese pythons, which are native to Southeast Asia, are believed to be living in the Everglades, where they thrive in the warm, humid climate. While many were apparently released by their owners, others may have escaped from pet shops during Hurricane Andrew in 1992.
The pythons can grow to be 26 feet long, and they have been known to swallow animals as large as alligators. They and other constrictor snakes kill their prey by coiling around it and suffocating it.
In 2010, Florida banned private ownership of Burmese pythons.