At the turn of the century, Burmese pythons discarded by their owners began to establish themselves in the Everglades. Now they are invading the sensitive Florida ecosystem, pushing all other animals there to the brink of extinction.
Research conducted between 2003 and 2011 provided data that showed how animal populations changed in response to the snake intrusion. Those include raccoons, whose populations have dwindled by 99.3 percent, oppossums - diminished by 98.9 percent, and even bobcats, who are 87.5 percent gone. White-tailed deer were down 94.1 percent. Foxes were also on the decline, and rabbits have disappeared completely.
The data was collected by Michael Dorcas of North Carolina's Davidson College. Dorcas and his colleagues conducted their study over 39,000 miles of the Everglade region, recording all the animals they saw between the years of research.
Burmese pythons were first recognized as an established species in the Everglades in 2000, but they do not belong there. They are native to Southeast Asia, but are often kept as pets. The accidental or purposeful release of them by their owners resulted in the troubling situation researchers are now observing.
These pythons can grow up to 16 feet long and weight up to 150 pounds. And while they don't normally pose a threat to humans in the wild, their disastrous effects on native mammal populations is easily seen, especially to people working in the Everglades, who noted a decrease in mammal sightings over the years.
"This is the first documentation of impacts on animal populations," said Dorcas, "and they are dramatic - with 99 percent declines in some cases." Deer, bobcats, rabbits, oppossums - "These were once very common animals in the Everglades," said Dorcas, "And now they're gone.
"Last October, we found a 50-foot snake with an 80-pound doe inside it."
The declines were sharp in all areas except for those in which Burmese pythons have not yet fully colonized, further pointing to the snakes as the culprits behind these drastic animal drop-offs.
This is an important example of human interference with a fragile ecosystem, and it is proving to be continuously threatening to the animals that remain in the Everglades.
Furthermore, the ripple effect of the python issue can also be seen: Cougars, coyotes, and alligators in the Everglades now risk sharp declines as well, due to their normal prey having been mostly snatched up by the snakes.
Another issue, said Dorcas, is that the snakes' prey are unfamiliar with such a predator, as they have not encountered them before, and as such, are unable to take the appropriate measures to avoid being killed. "It has been millions of years since there was a large snake predator in [what is now] Florida," Dorcas noted. "So the animals are naive in detecting or recognizing snakes as large predators."
"Thanks to the work of our scientists, there is a large and growing understanding of the real threat Burmese pythons pose to the Everglades," said Ken Salazar, Secretary of the Department of the Interior. According to a report by the Virtual News Room, this snake "has already gained a foothold in the Florida Everglades, and we must do all we can to battle its spread and to prevent further human contributions of invasive snakes that cause economic and environmental damage."
The U.S. Fish and Wildlife Service recently banned the import and interstate transport of the Burmese python - but reversing the ongoing invasion will take a lot of work.
"These snakes are notoriously hard to find, and very secretive," said Dorcas. Combine that with the fact that much of southern Florida is vast wilderness, and the odds of finding or suppressing the intruding pythons are long. It doesn't look promising, he said. "It's an ecological mess, and exactly what's going to happen down the road remains to be seen."
Photo: A Burmese Python. This snake poses a significant threat to animal populations in the Everglades. Wikipedia