Why Are Enormous, Alligator-Eating Pythons Invading Florida?

Giant snakes are devastating the Everglade ecosystem. An expert explains how this became a problem, and what, if anything, we can do to stop it.

Mike Rochford, University of Florida

America has a border problem, but it's not the one you're thinking about. Foreign invaders arrive in this country quietly, often in shipping containers from Asia or as exotic pets. At first, small populations are hardly noticed. Then, when becomes apparent that these invaders have no natural enemies here, their numbers explode exponentially. 

America can't keep invasive plants and animals out of its ecosystems, and stories of their destruction continually appear in the news cycle. For the past few years, increasingly large swarms of Asian stink bugs have been destroying apple harvests in the fall. Streams, rivers, and lakes in the heartland are teeming with Asian Carp -- fish that routinely cause injury to boaters, jumping up from the water when provoked. There are also less visual stories concerning invasive species, such as Emerald Ash Borers, insects that have killed tens of millions of trees across the country in the past decade. In all, invasive species cost the U.S. $120 billion a year, both in damages and containment. 

And now Burmese pythons are capturing headlines. These snakes can grow to 16 feet and eat almost anything -- even alligators (click if you dare, it's a photo of an alligator carcass and a dead python that burst open while devouring it). Since 2003, as a new study in Proceedings of the National Academy of Sciences notes, the increase of the python population from just a few to perhaps a few thousand has been connected to declines of several native mammals. According to the study, observations of raccoons have declined 93 percent, bobcats by 87 percent, and possums by 98.9 percent. The Everglades are enormous -- nearly 4,000 square miles -- and it is difficult terrain to traverse. So it's hard to say how the pythons have affected rarer, quieter species such as egrets.

Recently, Michael Dorcas, professor of herpetology at Davidson College and lead author of the study, spoke with The Atlantic about how pythons became a problem, and what, if anything, we can do to stop them.

Do researchers have a sense of how quickly the python population is expanding?

We really don't. Basically, my answer to that is there are a lot of pythons out there. I found more pythons in the Everglades National Park than I found rat snakes, which are one of the more common species of snakes in the eastern United States.

Determining, or even estimating, how many snakes are out there is very difficult because snakes are very secretive. They remain inactive for much of the time, and to determine actual densities of snake populations requires mark-recapture studies. But all of the pythons that are captured in the park are actually removed from the park, so that precludes us from doing mark-recapture studies. I would certainly feel comfortable saying there are thousands of snakes, but there may be many orders of magnitude more than that.

People keep pet snakes all across the country. Why is it that they have found such a suitable home in Florida?

Certainly the climate and habitat is very suitable for these snakes there, or it appears to be. There are these vast areas of wilderness that, at least at one time, had abundant prey. The climate is subtropical, so it facilitates their survival and reproduction.

When did it become apparent that pythons were overtaking the Everglade ecosystem?

Pythons have been found in various places throughout the United States for a number of years and have been a mainstay of the reptile pet trade for decades. Pythons would turn up here and there, even in places like Charlotte, North Carolina, where I live now, and including the Everglades National Park, even back in the 1980s and 1990s. But it wasn't until the year 2000 that they were recognized as an established, reproducing population. Since that time, they have increased their numbers dramatically. If you compare the mammal populations to before they started proliferating to the mammal populations now, you see these drastic increases we report in our research article.

Presented by

Brian Resnick is a staff correspondent at National Journal and a former producer of The Atlantic's National channel.

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