Pythons wiping out mammals in Everglades, researchers say
A Burmese python in the Everglades swallowed a 76-pound deer last year.
January 31st, 2012
09:34 AM ET

Pythons wiping out mammals in Everglades, researchers say

Burmese pythons have eaten so many small mammals in Everglades National Park that populations of rabbits and foxes have disappeared and numbers of raccoons, opossums and bobcats have dropped as much as 99%, according to a report released Tuesday by researchers at Virginia Tech University, Davidson College and the U.S. Geological Survey.

“Pythons are wreaking havoc on one of America’s most beautiful, treasured, and naturally bountiful ecosystems,” said U.S. Geological Survey Director Marci McNutt in a statement.

The massive nonnative snakes have become an established species in the park in the past 11 years, after snakes that were once pets were released into the wild, according to the researchers. Park spokeswoman Linda Friar said earlier this month that there are tens of thousands of the snakes in the park.

In the remote southernmost regions of the 1.5 million-acre national park, researchers could find no marsh or cottontail rabbits or foxes. In those same areas, the raccoon population has declined 99.3%, the opossum population 98.9%, and the bobcat population 87.5%, the researchers reported.

Those animals are often found in the stomachs of Burmese pythons captured in the Everglades, the researchers said.

“The magnitude of these declines underscores the apparent incredible density of pythons in Everglades National Park,” said lead author Michael Dorcas, a biology professor at Davidson College in North Carolina.

To measure the population declines, researchers traveled more than 39,000 miles at night along roads in the park between 2003 and 2011, counting both live animals and road kills. Their data were compared to similar counts made along the same roads in 1996 and 1997, before the Burmese pythons had become an established species in the park.

In northern areas of the park, where python populations have not become established, the researchers found similar mammal numbers between their recent and older surveys. But in the area where the pythons have recently become established, the researches reported a noticeable decline in mammal numbers. They called for action before the pythons wipe out mammals in the entire park.

“Right now, the only hope to halt further python invasion into new areas is swift, decisive, and deliberate human action,” McNutt said.

Burmese pythons are native to southeast Asia, their range extending from southern China to the Malay Archipelago, according to the National Zoo. The snakes reach breeding age in four to five years and a female lays an average of 35 eggs during the spring breeding season, though one snake may lay up to 100. Burmese pythons can live as long as 30 years.

In their native range, the snakes are considered threatened and are hunted by humans for their meat and skins, according to the National Zoo.

They may grow up to 22 feet long but average about 16 feet. The snakes can swallow whole animals four or five times the size of their head. In the Everglades, the pythons have been found to eat deer and even alligators.

While the researchers are concerned about the fate of the raccoons and the opossums, they say they may not even be able to measure the snakes' effect on more elusive species.

“Such severe declines in easily seen mammals bode poorly for the many species of conservation concern that are more difficult to sample but that may also be vulnerable to python predation,” Dorcas said in a statement.

The researchers compared the proliferation of pythons in Florida to that of the brown tree snake on the Pacific island of Guam, where native species have disappeared since the introduction of the snakes. But they said it's happening faster in Florida.

“It took 30 years for the brown tree snake to be implicated in the nearly complete disappearance of mammals and birds on Guam; it has apparently taken only 11 years since pythons were recognized as being established in the Everglades for researchers to implicate pythons in the same kind of severe mammal declines,” U.S. Geological Survey scientist Robert Reed said in the report.

Earlier this month, the U.S. Fish and Wildlife Service instituted a ban on the importation of the Burmese python and three other nonnative constrictor snakes - the yellow anaconda and northern and southern African pythons.

But the researchers say they'll still need to do more.

“This severe decline in mammals is of significant concern to the overall health of the park’s large and complex ecosystem,” Everglades National Park Superintendent Dan Kimball said in a statement. “We will continue to enhance our efforts to control and manage the non-native python and to better understand the impacts on the park.”

The latest research was published this week in the Proceedings of the National Academy of Sciences.

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Filed under: Animals • Florida • Snakes
soundoff (456 Responses)
  1. Playjojo

    How adult of you. Thank you for sharing.

    January 31, 2012 at 10:59 am | Report abuse |
  2. anna

    Why are these snakes allowed to live and breed??

    Kill them all.

    January 31, 2012 at 11:00 am | Report abuse |
  3. ELH

    I suppose that the snakes have no 'natural' enemies in the Everglades (besides humans and the occasional really BIG gator. It would seem that total eradication is the only option, but snakes don't congregate, are naturally secretive and able to move freely on dry land, swamp and water. Even intensive hunting for hide, flesh and bounty would probably not attract enough hunters to do much more than control the population.

    I wonder what will happen when the snakes finally run out of prey? Will their numbers subside or will they increase their range? In many other predator/prey relationships we see one decline as the other blossoms then the cycle will reverse (rodentscoyotes).

    January 31, 2012 at 11:00 am | Report abuse |
  4. anna

    Sad but true lol

    January 31, 2012 at 11:01 am | Report abuse |
  5. Tanner

    There are millions of Southeast Asians in the States. A lot of them are poor. A lot of them would probably jump at the chance to use their skills in hunting these things down and selling the skin to manufacturers and the meat to Asian stores and restaurants. It would be a win-win-win situation. It would also probably be like shooting fish in a barrel.

    January 31, 2012 at 11:02 am | Report abuse |
  6. MIKE

    Just have a hunting season for the dam snakes. Hunters will take care of the problem for free. Don't introduce a predator or we will have that problem in several years

    January 31, 2012 at 11:02 am | Report abuse |
  7. walt stanish

    bounty for every python head tuned in!

    January 31, 2012 at 11:02 am | Report abuse |
  8. Darrel

    Quit dancing around the pole and do what has to be done. Snake skin boots, belts etc and a bounty for every dead snake. No closed season. Ban all exotic reptiles and fish. You want a python or carp, visit asia. DO IT>

    January 31, 2012 at 11:03 am | Report abuse |
  9. WasabiPotPie

    I was thinking the same thing about your mom.

    January 31, 2012 at 11:03 am | Report abuse |
    • Buster Bloodvessel

      His mom has actually posted here before telling him to stop.

      January 31, 2012 at 11:58 am | Report abuse |
  10. SPENT

    Guess we need to get the EPA to stop this, hey? Maybe let's have a new governmental agency to stop the snakes from killing these species.

    January 31, 2012 at 11:04 am | Report abuse |
  11. Kenny

    If we can find a way to eliminate those non-native pythons from the Everglades, we could use the same process to rid ourselves of ALL of those native snakes in our "Do Nothing Congress" and do it cheaply.

    January 31, 2012 at 11:04 am | Report abuse |
  12. dave

    Did IQ's in Florida suddenly take a nose people in the Fish & Wildlife Service have been reporting this problem for year and this is the best you can do..maybe it is time you place a State bounty on these snakes and start paying people to kill them...NOW

    January 31, 2012 at 11:04 am | Report abuse |
  13. chilly g

    we need to get rid of those snakes and the best way is to offer something to hunter for killing the snakes,MONEY.

    January 31, 2012 at 11:06 am | Report abuse |
    • Mister golf


      January 31, 2012 at 11:16 am | Report abuse |
  14. Chuck Anziulewicz

    These are pretty big snakes. There must be a lot of meat on them. Would they be good to eat? Maybe there could be a cottege industry in python cuisine.

    January 31, 2012 at 11:07 am | Report abuse |
    • Roger

      Probably taste like chicken; most snakes actually do.

      January 31, 2012 at 11:14 am | Report abuse |
  15. Aacon

    Just tell the Chinese the Burmese pythons located in the Everglades National Park only acts as aphrodisiac & promotes a male offspring.The snake problem will be fixed in 7 days.

    January 31, 2012 at 11:07 am | Report abuse |
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