Madison Area Herpetological Society

Pythons in the Florida Everglades: Fact vs. Fiction


                        Lacy the Granite Burmese Python (Python bivittatus)

Pythons in the Florida Everglades:
Separating Fact from Fiction

There is little doubt by now that most have heard, or are aware of the long standing controversy surrounding exotic, or nonnative pythons in Florida’s Everglades, particularly the Burmese python (Python bivittatus). Over the past decade or more, there has been significant media coverage, often to the point of sensationalism and hysteria surrounding how these snakes got there, their numbers, their impact on society, wildlife, and natural resources, as well as their adaptability or survivability elsewhere in the United States. While it can be agreed that pythons do not belong in FL’s Everglades, this quick handout is designed to place the issue in perspective and separate fact from fiction.

Myth: Burmese pythons are poised to expand and colonize areas northward of southern Florida.
Fact: This finding was made from a highly novel, yet imprecise set of narrowly chosen data points in a 2008-2010 U.S. Geological Survey. This report has been widely criticized as “unscientific” by an independent panel of 11 herpetologists and other scientists from Texas A&M, National Geographic, and others, and its peer review process can be considered questionable.

This report only used the means, or averages of two climatic variables (monthly temperature and monthly precipitation) to make is projection while ignoring the associated temperature extremes. Subsequent and follow up cold weather research on Everglades pythons using similar methodology in Florida and other Southeastern states has found 100% direct or indirect mortality in pythons (through fatal respiratory infections) despite even dynamics in some of the studies that were designed in the python’s favor. More rigorous climate modeling and matching using 19, rather than 2 climatic variables has projected a far smaller inhabitable range for pythons in the U.S., which included only portions of southern Florida and Texas.

Myth: There are between 10,000 and 100-150,000 Burmese pythons in south Florida and the Everglades Fact: There is no legitimate science beyond speculation that supports these estimates. This is also a very wide margin of speculation. There are currently no reliable estimates on the numbers of pythons there may be in the Everglades that can be supported using sound science.

Myth: Large constrictors are dangerous animals that present considerable public safety risks.
Fact:  There have been 10 constrictor related fatalities since the year 1990, with at least one case being proven to have been fraudulent (i.e. the snake did not kill the person). This amounts to an average of only 0.4 constrictor related deaths per year. There have also been no reports by Florida FWC of any unprovoked attacks on tourists by pythons in the everglades. Any accidental and premature death is a tragedy; however, all incidents that have occurred were either voluntarily accepted or occurred within the household/facility housing the snake. There have been 1,111,768 large constrictors imported into the U.S. according to Georgetown Economic Surveys, with the number of captive bred and born animals likely being much higher. 10 fatalities amounts to less than one one-thousandth of a percent, or 0.0008%.

Only one fatality can be attributed to Boa constrictors. This occurred in Nebraska in 2010, and likely involved extreme inebriation. Even then, this case was highly unusual and suspect in that two adult men should have been able to handle even a large adult Boa constrictor.

Myth: Irresponsible pet owners are to blame for a significant cause to the introduction of pythons in FL.
Fact: While independent pet releases or escapes have undoubtedly occurred in and near Florida’s everglades and elsewhere, they are not a major contributing factor to the presence of pythons in FL. Research conducted on Everglades National Park pythons at the genetic and molecular level have shown strong genetic similarity among a majority of snakes, which strongly ties to the mass unintentional release of snakes due to a catastrophic weather related event (such as Hurricane Andrew in 1992). While it may be true that the pet trade is still technically to blame, people have not been travelling from across the U.S. with the intent of releasing their unwanted pet snakes specifically into the FL everglades. That is fiction.

Myth: Burmese pythons are wiping out mammal populations in FL. Pythons have also been consuming 77% of the Everglade’s rabbits.
Fact: The ENP mammal studies that have been performed failed to link any direct causation in area mammal declines to the Burmese python. The study was largely speculative and correlative, as correlation does not imply causation. This flaw was reinforced by even on the study’s co-authors, Frank Mazzotti, following publishing of the study.

The newer, and more recent study as of 2015 linking marsh rabbit declines to pythons was a sturdier study, but still had several methodological flaws. These flaws included assumed outcomes by selecting areas in which pythons were already known, as well as small sample sizes of only 24 rabbits at one test site, and small number of sample control sites overall. 77% used on its own simply does not provide adequate context into sample sizes or number of study sites.

Myth: These snakes belong in the wild/jungle.
Fact: MAHS certainly doesn’t disagree that populations of feral pythons in southern Florida do not belong there, and efforts should be made to remove and eradicate them. However, when it comes to the ownership of pet snakes, the vast majority of the species in question are now widely and regularly bred in captivity for numerous generations, oftentimes in particular color and/or pattern variations known as “morphs”. These morphs and captive born counterparts simply lack the necessary characteristics for survival in the wild. Simply put, all animals kept as a pet or for any other purpose in captivity originated, at one point or another, from “wild” counterparts.

Myth: Firefighters and emergency first responder personnel expend considerable resources on exotic animals, and are often put at additional unnecessary risk.
Fact: While some animals may present some level of voluntarily accepted occupational risk (and not a public safety issue), no firefighter or other emergency first responder personnel has been incidentally attacked, bitten, or otherwise harmed by a captive reptile (or other exotic) while responding to or performing their usual line of duties. In fact, many emergency first responders have gone above and beyond in their line of duties by rescuing reptiles (and other exotic species) in crisis situations, just as with any other pet (dogs, cats, etc). Furthermore, numerous local, regional, state, and national individuals, organizations, and other stakeholders with the knowledge and expertise in dealing with these animals are readily available to assist public officials with situations involving these animals whenever possible using knowledge and methods that ensure animal welfare, public health and safety, and any environmental concerns are met. This is a common sense solution to issues such as these.

Myth: I just don’t understand why anyone would want to have a pet snake/reptile/other exotic. They’re not affectionate or able to be trained.
Fact: This demonstrates a lack of knowledge and understanding of pet ownership, and why it may be practiced. While many reptiles & amphibians may lack the same cognitive abilities as a dog, cat, or other mammal, many species are nevertheless very intelligent and perceptive animals (i.e. monitor lizards and tegus, and even many turtles and tortoises) that can be interacted with in a mutually positive manner when maintained properly. Many are interested and fascinated by these animals in their own rights, and do not have the added expectations of companion animal ownership. It is proven that even a one sided relationship with keeping animals for reasons other than companionship (such as personal, academic/institutional, or educational) can often further an interest/development in the sciences, as well as numerous health, personal, and academic benefits described elsewhere. This holds especially true when other opportunities are much more difficult or limited. Ultimately, we don’t expect everyone to fully understand the reasons for anyone wishing to keep any particular animal, but we do simply encourage recognition of the fact that each individual has different likes and interests, and that the society we live in is not in fact homogenous.

Myth: Wild Animals/Snakes/Reptiles are Not Pets!
Fact: This begs the question, “says whom?” As previously mentioned, many herp (reptile and amphibian) species have long been widely bred in captivity for many generations, often selectively for hundreds of different colors and/or patterns. While there can be some valid debate on the level of “domestication” in which many species have undergone through selective breeding and propagation, captive bred reptiles & amphibians in general are not “wild” animals in the sense that many are no longer wild caught or otherwise directly removed from the wild, and clearly undergo some form of human intervention through breeding. Domestication also does not completely eliminate natural drives or behaviors from animals undergoing the process that may be a negative consequence of poor or irresponsible care and negligence, be it a dog, a snake, or horses, for example. The American Pet Products Association (APPA) estimates there to be at least 4.9 million households with reptiles, and at the very least 9.3 million reptiles owned in the U.S., which is based on respondent data alone. Therefore, these animals most certainly are pets.

Myth: Owning a reptile/exotic is selfish! All of these arguments are just self serving.
Fact: While everyone is entitled to their opinion, MAHS must point out that owning any pet can be considered selfish. Many species of animals traditionally viewed as domesticated have been and continue to be raised and selectively bred by humans for unnatural and desirable traits, or otherwise for the essentially the same reasons. Therefore, wanting to keep a captive bred reptile or amphibian is not any more “selfish” than wanting a pet dog, cat, or other animal, and may in fact, be less so in many cases considering many use their animals in scientific, education and outreach efforts.

Myth: When introduced into Florida or elsewhere, these snakes have no natural predators.
Fact: This is only partially true. Southern Florida is the only region of the United States in which established, breeding populations of these pythons exists. Hatchlng Burmese pythons typically range from 18 to 24 inches, and can be predated upon by many indigenous animals including alligators and crocodiles (American), birds of prey and predatory wading birds, many species of carnivorous mammals, other indigenous snakes (i.e. kingsnakes and indigo snakes), and even large fish. While these may not be species pythons coexist with within their natural range, they will nevertheless readily consume hatchling pythons, which, along with aforementioned temperature and climatic extremes, thereby contribute significantly to their mortality rates.

Myth : Still, No one should be allowed to keep these animals. They need to be outlawed.
Fact:  While everyone is certainly entitled to their opinion, MAHS disagrees, and believes that these animals can and should be maintained by knowledgeable and responsible individuals provided others are not adversely affected. Irresponsibility and negligence can occur with everything, and collective punishment (penalizing a majority for the actions of a few) has been shown to be ineffective and unsuccessful. Simply holding an ideological or philosophical objection to keeping certain animals is not valid or sufficient grounds for enacting public policy. There are numerous scientific, educational, conservation, and societal/medical benefits associated with maintaining these animals in captivity that can be proven to be valid. While we don’t expect everyone to be interested in keeping reptiles, or to even like them, all that is asked for is for those who do not to understand and respect those that do.

Both the states of Florida and Texas, as well as Hawaii and other U.S. Territories in which may be hospitable for pythons, such as Puerto Rico, have already enacted state and territory specific restrictions on the possession and trade in these species. Large constrictors have long been widely held pets in all 48 continental states for well over the past century, and as such, are not a new phenomenon. Simply put, if these snakes had the potential to migrate northward or to become invasive within any other areas of the continental U.S. outside of southern Florida, there would already be populations elsewhere.

If you wish to learn more about this issue and other current news and events concerning herpetology and reptile keeping, as well as references used in this document, visit the Madison area Herpetological Society (MAHS) and United States Association of Reptile Keepers (USARK) at the links below.

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