Invasive Burmese pythons, descended from former pets that were released into the wild, are doing an incredibly effective job of wiping out anything that's small, furry, and native to the Everglades. And a new study published this week shows that the local wildlife basically has no defense... except
As this webcomic giving a brief history of Florida pythons illustrates (complete with thrilling snake-wrestling sequence), the study involved placing radio trackers onto rabbits and releasing them into designated areas both within and outside of the national park. At first, the bunnies did what bunnies do, and bred with their usual speed. But nine months later, 77 percent of the population within the Everglades, aka prime python turf, had been gobbled up. The control group, released outside the park, suffered no such fate.
Though the python problem is well-known (as is the fact that pythons breed like, uh, rabbits — the comic details the finding of one 17.6-footer with 87 fertilized eggs inside), the scientists were still taken aback, according to CBS News.
"All of us were shocked by the results. Rabbit populations are supposed to be regulated by factors other than predation, like drought, disease," study co-author Bob Reed, chief of the invasive branch of the United States Geological Society.
"They are so fecund. They are supposed to be hugely resilient to predation," he said. "You don't expect a population to be wiped out by predation."
And there was no doubt what happened to the rabbits. No doubt whatsoever, according to paper co-author Robert A. McCleery of the University of Florida:
"Every one (of the rabbits) we are saying was eaten by a python, we found inside a python," he said. "It wasn't like, 'I wonder what ate this.' You are looking for your rabbit and you find a python. The radio collar was transmitting from inside the python."
As pythons feast their way through the region, consuming not just rabbits but deer, raccoons, and possums (and chasing away those animals' natural predators, like bobcats, in the process), scientists are grappling with what's next for the Everglades' rapidly changing ecosystem. It's a particularly poignant point, because as National Geographic notes, "Everglades National Park was the first national park established to preserve biological diversity and resources, not for scenic views."
Stricter laws and regulations won't have any effect on the existing python population, which is estimated to be as high as 10,000. Even in a park as big as the Everglades, that's significant. The scientists involved in the rabbit study note that it would be nearly impossible to eradicate the snakes through poison or other means that've been used on rats and other invasive species.
The best that can be done, it seems, is to prevent them from spreading further, and to keep a close eye on what naturally happens next. Davidson College scientist Michael Dorcas was cautiously optimistic, telling CBS News that Everglades mammals' best/only hope is to wise up and adapt. Like, ASAP.
"One of the reason pythons have caused such dramatic declines in mammals is because mammals are naïve to pythons as major predators," he said. "So if that is the case and if there are mammals that do avoid pythons and that behavior is heritable, then we should see the fairly rapid evolution of mammals that would avoid pythons. Whether that will happen or not, we don't know."
Read the complete scientific paper in Proceedings B here.
Top photo by Flickr user Ted