Evidence that Burmese pythons and Indian pythons crossbred somewhere down the line could spell greater problems for Everglades National Park wildlife/NPS

Burmese pythons have made a huge dent on wildlife in Everglades National Park, and now a determination that some have crossbred with Indian pythons means the constricting snakes could slither out of the swamps and onto higher ground in search of their meals.

Past studies have attributed huge declines in raccoons, opposums, and even bobcats to Burmese pythons, which can easily grow beyond 10 feet in length and weigh 250 pounds.

"Numerous lines of evidence implicate introduced Burmese pythons as the primary cause of dramatic declines of several species of once-abundant mammals in (Everglades National Park)," said the authors of a 2011 study examining the prey-predator dynamic. "The timing of the python proliferation in ENP coincides with reductions in mammal abundances."

"The most severe declines, including a nearly complete disappearance of raccoons, rabbits and opossums, have occurred in the remote southernmost regions of the park, where pythons have been established the longest," U.S. Geological Survey researchers said at the time.  "In this area, populations of raccoons dropped 99.3 percent, opossums 98.9 percent and bobcats 87.5 percent.  Marsh and cottontail rabbits, as well as foxes, were not seen at all."

Now adding to the concern over what damage the snakes might do to the park's wildlife is a finding that some of the Burmese pythons have interbred with Indian pythons. Just 13 of 426 snakes sampled were found to have genes traced to both species, but that could be enough to alter the habits, and habitat preferences, for the progeny. The concern over that is that the Burmese variety tends to favor swamps for their habitat, while the Indian variety seeks out drier ground.

“If the Indian pythons have a wider range, perhaps these Everglades snakes now have that capability,” USGS geneticist Margaret Hunter, who was the lead author on the paper discussing the hybridization, told the Miami Herald. 

Because Burmese pythons pose a significant threat to the Everglades ecosystem, along with state, federal, tribal, and local partners, Everglades National Park and the Florida Wildilfe Commission have invested millions of dollars and countless hours in developing and testing ways to remove pythons from the Everglades. Currently, the approach to try to dent the population is to contract with snake hunters. 

 The park used volunteers for removal in the past, and while it will continue to do so, the addition of FWC contractors will allow greater numbers of skilled people to engage in removals than ever before.