Unwelcome Visitors: The Everglades Python Incursion

Photograph Credit: David Behrens

In February of 2004, several tourists visiting the Pa-hay-okee Overlook in Florida’s Everglades National Park were expecting the chance to observe the ecosystem’s beautiful variety of wildlife. What they encountered was a strange and unusual battle between two giant reptiles. A Burmese python and American alligator were locked in a struggle with each other, a very rare sight at the time. The large constrictor snake coiled itself around the alligator in an attempt to overpower and asphyxiate its large competitor. However, the alligator escaped the serpent’s grasp by rolling swiftly (a well known maneuver among crocodilians named the “death roll”). Free from the python’s coils, the alligator quickly seized the snake and delivered a fatal strike with its powerful jaws.[1] As the victorious crocodilian swam off into the swamp with the snake’s carcass still clenched in its jaws, the tourists remained awestruck by the event they just witnessed. It was, in reality, an abnormal scenario; these giant pythons did not always exist in Everglades National Park, or anywhere else in Florida. In fact, the population of Burmese pythons originates in an entirely different continent. The introduction of these large reptiles into the Floridian habitats poses a great danger to the native species and has been a cause of alarm among citizens, as these snakes are also very capable of attacking and killing children. Burmese pythons have thrived in the tropical environments of Everglades National Park and surrounding areas, and as the population of this large and deadly species continues to grow, so does the level of danger it presents for the ecosystem and its many vulnerable species. Large enough to threaten even an adult alligator, these animals are more than capable of killing nearly any creature it can ambush. So then, how exactly did these foreign reptiles arrive at Florida’s precious ecosystem, and does the future of the Everglades’ wildlife look grim under the pressure of this invasive species’ coils? A study on these snakes and their impact on the environment is clearly in order.

The Burmese python (Python molurus bivittatus) is indeed a tough customer, with the potential to reach a length of more than 20 feet and a weight of around 200 lbs. This Southeast Asian constrictor possesses poor eyesight at best, and so must rely on chemical receptors in their tongues as well as heat sensors along their jaws to pursue their prey effectively.[2] Once the python is able to approach its prey, it quickly strikes at the target, gripping the animal tightly using its sharp, back-wards pointing teeth. The snake then pulls its prey in and wraps its coils around its victim (the snake may also pull itself over to the prey in the case of a large, heavy target). With the animal now in the grip of the snake’s powerful coils, the final stage of the killing process can now take place. As the trapped creature breathes out, the python tightens the grip of its coils and makes it much more difficult for the creature to draw in oxygen. Eventually, the prey asphyxiates and dies. On some occasions, the python exerts so much force on its prey that it actually ruptures the animal’s blood vessels, causing it to die from internal bleeding instead.[3] The Burmese python, like all snakes, is unable to chew flesh. Instead it simply swallows its prey whole (with the animal often several times larger than the snake’s own head). Special elastic ligaments in the snake’s jaw allow it open its mouth wide enough to devour its prey whole.

The Burmese python is a large and powerful reptile which preys on a wide variety of species. HonoluluZoo.org

These pythons are designed to overpower relatively large animals, allowing them to select from a wide variety of prey such as rabbits, birds, and even other snakes. They are capable of surviving without food for long spans of time with little to no effects on their health.[4] The traits make the Burmese python a superb survivor, whether in Southeast Asia or in the swamps of Florida. Sightings of these snakes in the wild were once rare in Florida. Over the years, however, encounters with these snakes have grown until it became clear that a firm population had been established. Now the ecosystem is faced with a great problem consisting of possibly thousands of large, hungry serpents. This invasive species preys on many of Florida’s animals, including endangered species.

Scenarios such as the struggle between the Burmese python and the American alligator (Alligator mississippiensis) are no longer rare. There are several documented battles between the two large reptiles. Burmese pythons are known to occasionally kill their crocodilian competitors, whether in self-defense or for consumption. One particular case of a python preying on an alligator concluded rather unusually; although the python managed to kill and consume a six-foot-long alligator, the meal proved to be too much for the snake and the serpent’s body split open, revealing most of the alligator’s carcass. With younger alligators being preferred targets, it is possible that the Burmese pythons will alter Florida’s American alligator population. Although these battles may appear to be spectacles to some, they are actually events which show the impact these snakes could have on the more vulnerable species. After all, if Burmese pythons can compete with Florida’s largest predator, then all other species are fair game. The pythons also pose a great threat to children, as the snakes are capable of easily attacking and killing younger people. One attack in 2009 consisted of a young child being strangled by the family’s eight-foot-long pet Burmese python.[5]

Unable to hold its large meal, this python's body burst open, revealing the carcass of the alligator it consumed. nps.gov

The pythons also contribute to the economic damage toll created by other invasive species. This toll, along with the costs of controlling these invasive creatures, builds up to a massive $137 billion a year according to a 1999 Cornell University study.[6] This unfortunate situation can only grow worse as the pythons, as well as other foreign species, continue to breed and multiply in the rather comfortable climate they have been presented with.

In response to this growing threat, licenses to capture and kill these invasive reptiles have been issued. The python hunters commonly find snakes warming themselves at night on roads which were heated by sunlight during the day. Catching the dangerous serpents is surprisingly simple; with the hunter grabbing the snake by its tail and staying out of the python’s striking range. The snake repeatedly attempts to attack the hunter and eventually tires itself out, allowing the hunter to easily grasp the snake by the head. The snakes are euthanized, usually by severing the brain from the spinal cord. More than a thousand of these snakes have been found and removed over the years.[7]

Photograph Credit: Tanya Dewey, Animal Diversity Web, University of Michigan Museum of Zoology

Unfortunately, despite these attempts to weaken the snake population, the Burmese pythons have proven to be too numerous and successful at survival. The population was able to resist the effects of these captures and continued to thrive. These slippery snakes appeared to be unstoppable until the record low temperatures of 2009 and 2010 threatened the snakes as well as other foreign species. Unable to manage with the sudden drop in temperature, many snakes perished. This provided relief for many, and it appeared that the invasive population was under great pressure from the colder environment. Unfortunately, water managers have concluded that the problem is far from over. The constrictors are back, and continue to threaten the health of the ecosystem.[8] The cold snap was unable to eliminate the population, and their numbers are growing once again.

A Burmese python and an American alligator locked in a struggle. Both species are known to prey on each other. Photo Credit: Lori Oberhofer, National Park Service

So how did these troublesome pythons even make their way into Florida’s ecosystem in the first place? One significant cause of this frustrating problem is the pet trade. Although exotic pets like large constrictors may seem interesting to collectors as young specimens, they quickly prove to be too much to handle once they begin reaching a larger size. They rid themselves of their responsibility by simply releasing their overgrown pet into the wild. This is illegal and there are, in reality, humane alternatives to setting these dangerous reptiles free.[9] However, another, possibly more influential, cause may have been the destructive effects of 1992’s famous Hurricane Andrew. Several hatcheries in the area which housed many Burmese pythons were destroyed and the surviving snakes escaped into the wild. This is supported by the fact that many pythons which were recently caught or found dead possessed very similar DNA.[10]

It has proven incredibly difficult to keep the population of these snakes under control. Although the pythons may seem unstoppable, there are several ideas as to what can be done to weaken the population. Snake expert Dr. Lucas Joppa of Duke University in North Carolina, for example, states that the Burmese python require warm locations for the survival of their eggs. Joppa adds that by providing the snakes with a battery or solar powered electric blanket, an attractive place for female snakes will be produced that can allow hunters to easily find the snakes.[11]

The Everglades National Park is home to many unique species which are threatened by the presence of the invasive Burmese python. Photo Credit: National Park Service

For now, however, the rising Burmese python population continues to threaten both wildlife and people as these large reptiles continue to survive the variety of challenges thrown at them. These unwelcome visitors, though beautiful and interesting creatures in their own right, have no place in the habitats of Florida. Though research on finding an effective method of wiping them out continues, the future of the Everglades ecosystem continues to look grim under the negative effects of this foreign species.

[1] Lovgren, Stefan. “Huge, Freed Pet Pythons Invade Florida Everglades .” (2004): National Geographic.com. 03 Jun 2004.

[2] “Burmese Python.” National Geographic.com. Available from http://animals.nationalgeographic.com/animals/reptiles/burmese-python/. Internet; accessed 2 May 2011.

[3] “Burmese python.” WhoZoo.org. Available from http://whozoo.org/students/stamoo/pythonhtml.html. Internet; accessed 2 May 2011.

[4] Ibid

[5] “Girl, 2, strangled by pet python, police say .” (2009): msnbc.msn.com. 01 July 2009.

[6] Lovgren, Stefan. “Huge, Freed Pet Pythons Invade Florida Everglades .” (2004): National Geographic.com. 03 Jun 2004.

[7] Braun, David. “What it’s like to be a Florida python hunter.” (2010): National Geographic.com. 25 Jan 2010.

[8] Bennett, George. “Pythons are making a resurgence in the Everglades.” (2011): Palm Beach Post.com. 26 Mar 2011.

[9] Pimm, Stuart. “Pythons in Florida Everglades: Is the Snake Invasion Only Beginning?.” (2009): National Geographic.com. 06 Sep 2009.

[10] Sherwell, Philip. “A plague of Burmese pythons in the Everglades .” (2009): The Telegraph.co.uk. 02 Aug 2009.

[11] Pimm, Stuart. “Pythons in Florida Everglades: Is the Snake Invasion Only Beginning?.” (2009): National Geographic.com. 06 Sep 2009.

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