The Florida Everglades are home to dozens of snake species, making the region one of the most snake-rich landscapes in the United States. At least 26 native species live there, from harmless water snakes and racers to venomous cottonmouths, diamondback rattlesnakes, and coral snakes. But the Everglades have also become ground zero for one of the most damaging reptile invasions ever recorded: the Burmese python, a Southeast Asian constrictor that now numbers in the tens of thousands and has reshaped the ecosystem in measurable, alarming ways. The story of Everglades snakes is really two stories layered on top of each other, one about a naturally diverse wetland and one about what happens when an apex predator from another continent moves in.
Native Snakes of the Everglades
South Florida’s warm, wet climate supports a wide variety of native snakes. Most are non-venomous species that fill distinct ecological roles. The Florida kingsnake, various rat snakes, ribbon snakes, mud snakes, and several water snake species all thrive in the mix of sawgrass marsh, hardwood hammock, and mangrove habitat that defines the Everglades. Many of these species are secretive, nocturnal, and rarely seen by visitors.
On the venomous side, the Everglades host representatives of both families of venomous snakes found in North America: pit vipers and coral snakes.1PubMed Central. Venomous adversaries: a reference to snake identification, field safety, and bite-victim first aid for disaster-response personnel deploying into the hurricane-prone regions of North America The eastern diamondback rattlesnake, the dusky pygmy rattlesnake, the Florida cottonmouth (water moccasin), and the eastern coral snake all inhabit the region. The cottonmouth is by far the most commonly encountered venomous species, especially around canals and levees. Coral snakes are present but reclusive; their small mouth and rear-fang-like bite delivery make encounters rare and envenomations even rarer. Despite the number of venomous species in the area, snakebite is uncommon among the more than one million annual visitors to Everglades National Park.
How Burmese Pythons Took Over
Burmese pythons are native to Southeast Asia, where they inhabit tropical and subtropical forests and wetlands. They began appearing in the Everglades in the 1980s, almost certainly released or escaped from the exotic pet trade. South Florida’s climate, abundant prey, and lack of natural predators large enough to threaten an adult python created near-perfect conditions. By the early 2000s, the population had clearly established itself and was reproducing in the wild. Today, researchers estimate the population in the tens of thousands, though precise counts are difficult because the snakes are exceptionally good at hiding.
Radio-tracking studies show that Burmese pythons in southern Florida prefer forested habitats with canopy cover and avoid areas of deep open water, despite the popular image of them swimming through sawgrass marshes.2Journal of Herpetology. Habitat Selection by the Invasive Species Burmese Python in Southern Florida They gravitate toward broad-leafed and coniferous forest and tend to avoid the deep-water marshes that dominate roughly 43% of the study area. Tree islands, canal levees, and hardwood hammocks serve as prime python habitat, which also happens to be where many native mammals concentrate during wet seasons.
The Collapse of Everglades Mammals
The most dramatic consequence of the python invasion is the near-disappearance of mid-sized mammals from the core of Everglades National Park. A landmark study compared nocturnal road surveys before and after the python population exploded. Raccoon sightings dropped by about 99%, opossum sightings by about 99%, and bobcat sightings by roughly 88%. Rabbits were no longer detected at all. These declines tracked spatially with python density: mammal populations were still relatively healthy in areas where pythons had only recently arrived and were most abundant outside the python’s established range.3PubMed Central. Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park
Follow-up experimental work confirmed the link. Researchers translocated marsh rabbits into python territory and tracked them. Within 11 months, pythons accounted for 77% of rabbit deaths, and predation pressure was intense enough to prevent any rabbit population from persisting in the park.4PubMed Central. Marsh rabbit mortalities tie pythons to the precipitous decline of mammals in the Everglades The pythons have effectively removed an entire trophic layer from the ecosystem. This kind of top-down pressure, where a single introduced predator reshapes the food web beneath it, is exactly what ecologists feared when the invasion was first recognized.
The loss of mammals has cascading effects that researchers are still documenting. Raccoons, for instance, were once major nest predators for turtles and ground-nesting birds. With raccoons gone, some species may actually benefit temporarily, but the overall food-web disruption is severe. Pythons consume mammals, birds, and other reptiles indiscriminately.5PubMed. Management of invasive snakes in coastal environments: A baseline assessment of the Burmese python invasion in the Florida Everglades
Pythons and Everglades Birds
The threat extends well beyond mammals. Researchers examining the gut contents of 85 Burmese pythons in Everglades National Park identified 25 species of birds from nine different groups. Rails and their relatives were the most common prey, making up about 36% of birds consumed. Herons and bitterns accounted for another 18%. Among the species found were pied-billed grebes, white ibises, and limpkins. Several of the consumed species are of special conservation concern in Florida, including the little blue heron, snowy egret, white ibis, and limpkin. One, the wood stork, was federally listed as endangered at the time of the study.6The Wilson Journal of Ornithology. Birds Consumed by the Invasive Burmese Python (Python molurus bivittatus) in Everglades National Park, Florida, USA
Pythons do not just catch individual birds in the field. They have learned to exploit wading bird nesting colonies, consuming nestlings, fledglings, and eggs. In one monitored season, pythons were responsible for predation at about 4% of all monitored nests across multiple colonies, a rate five times higher than that of native predators at the same sites.7Biological Invasions. Invasive Burmese pythons (Python bivittatus) are novel nest predators in wading bird colonies of the Florida Everglades Environmental DNA sampling confirmed that pythons are drawn to these colonies: python eDNA was detected at 88% of wading bird colony sites compared to 42% of nearby control sites, and the concentration of python DNA at colonies was roughly ten times higher than at controls.8PLoS ONE. Environmental DNA sampling reveals high occupancy rates of invasive Burmese pythons at wading bird breeding aggregations in the central Everglades Wading bird colonies are huge, predictable food sources, and the pythons have apparently figured that out.
A Parasite Hitchhiker
The Burmese python did not arrive alone. It brought a lung parasite from Southeast Asia, a pentastomid called Raillietiella orientalis, that has spilled over into native Florida snakes.9PLoS ONE. Host-specific phenotypic variation of a parasite co-introduced with invasive Burmese pythons Researchers have now found this parasite in at least 13 species of native snakes in areas where they share habitat with pythons. The troubling twist is that native snakes appear to be even better hosts for the parasite than the pythons themselves. Infection rates and parasite loads are higher in native snakes, and the parasites grow larger in them, suggesting the native species lack evolutionary defenses against this unfamiliar organism.10Ecosphere. Highly competent native snake hosts extend the range of an introduced parasite beyond its invasive Burmese python host
This means the python invasion threatens native snakes in two ways: directly, through competition and predation, and indirectly, by introducing novel parasites. The parasite’s range now extends beyond the python’s own range because infected native snakes can carry it into new territory. For already-stressed native populations, an additional disease burden is a genuine concern.
Other Invasive Constrictors
The Burmese python gets most of the attention, but it is not the only large exotic snake established in southern Florida. Northern African pythons and boa constrictors are also reproducing in the wild. Environmental DNA assays designed to detect five large constrictor species confirmed Burmese python DNA at 37 out of 63 sampling events, though the other target species were not detected in those particular surveys.11PLOS ONE. Environmental DNA Sampling Improves Occurrence and Detection Estimates of Invasive Burmese Pythons Green and yellow anacondas have also been flagged as species with the potential to become established in the region.
A risk assessment of non-native boas and pythons in the United States identified boa constrictors, ball pythons, and reticulated pythons as posing particularly high invasion risks.12PubMed. An ecological risk assessment of nonnative boas and pythons as potentially invasive species in the United States The reticulated python, which can grow even larger than the Burmese, would be an especially worrying addition to Florida’s landscape. The ongoing exotic pet trade and the difficulty of preventing releases mean the pipeline of potential new invaders remains open.
How Far North Can Pythons Spread
One question that generates a lot of public interest is whether Burmese pythons could colonize the rest of the southeastern United States. The answer depends heavily on winter temperatures. Pythons are tropical animals with no behavioral instinct to seek shelter from cold and no physiological ability to tolerate freezing. Research has shown that their digestion is impaired or shut down for months in cooler climates, and a single bout of freezing temperatures kills them.13Wiley Online Library (Integrative Zoology). Environmental temperatures, physiology and behavior limit the range expansion of invasive Burmese pythons in southeastern USA Right now, this restricts the breeding population to the southern tip of Florida.
Climate modeling produces a range of predictions. One set of models concluded that global warming would actually contract suitable python habitat in the U.S. and worldwide, because the models emphasized the snakes’ inability to cope with temperature variability rather than just average warmth.14PubMed Central. Claims of potential expansion throughout the U.S. by invasive python species are contradicted by ecological niche models Other models using different climate-matching approaches projected that by the year 2100, suitable habitat could extend as far north as parts of Washington, Colorado, Illinois, Indiana, Ohio, Pennsylvania, New Jersey, and New York.15Biological Invasions. What parts of the US mainland are climatically suitable for invasive alien pythons spreading from Everglades National Park? The disagreement between these models reflects genuine uncertainty about which climate variables matter most for python survival. The more conservative view, which accounts for the snakes’ demonstrated cold intolerance, suggests that major northward expansion is unlikely anytime soon, but not impossible on a century-long timescale if winters warm substantially.
Are Pythons Dangerous to People
Given the size of Burmese pythons (adults commonly reach 3 to 5 meters), visitors understandably wonder about personal safety. Over a full decade of monitoring from 2003 to 2012, researchers documented just five apparently unprovoked strikes directed at humans in Everglades National Park. All five were aimed at biologists wading through flooded wetlands, not at hikers or casual visitors. Two resulted in minor injuries, and none progressed to constriction. Researchers characterized most of these incidents as “mistaken identity,” where a python struck at what it perceived as prey and then broke off the interaction.16Wildlife Society Bulletin. Assessing risks to humans from invasive Burmese pythons in Everglades National Park, Florida, USA During this same period, the park averaged over one million visitors per year. No strikes were directed at park visitors. The risk to a person walking boardwalk trails or paddling a canoe is, by any reasonable measure, extremely low.
That said, these are large, powerful constrictors, and treating them casually would be unwise. The risk assessment’s conclusion was not that pythons are harmless to humans but that the probability of a fatal encounter is very small. Keeping a respectful distance and not attempting to handle a wild python remain sensible precautions.
Detection and Control Efforts
Finding Burmese pythons in the Everglades is notoriously difficult. Their camouflage is superb, they spend much of their time hidden in dense vegetation or underwater, and the landscape itself is vast and largely inaccessible. Traditional visual surveys miss most animals. Environmental DNA (eDNA) sampling, which detects tiny traces of python DNA shed into waterways, has proven far more effective. In one survey of 28 sites across the Greater Everglades, python eDNA was detected at 25 of them, including sites where no python had ever been observed directly.17U.S. Geological Survey. Environmental DNA surveys of Burmese pythons in the Greater Everglades Ecosystem The technique helps identify new colonization fronts and dispersal corridors that visual surveys would miss entirely.
Researchers are also exploring biological lures. Male Burmese pythons reliably follow female scent trails, a behavior that has potential for trapping. In laboratory Y-maze trials, every male tested followed a single female chemical trail, while male-only trails did not attract the same interest.18PubMed. Male Burmese pythons follow female scent trails and show sex-specific behaviors If a synthetic pheromone lure could be developed, it might improve capture rates during the breeding season. That work is still in its early stages, and no field-ready pheromone trap exists yet.
On the ground, Florida runs multiple python removal programs. The Python Elimination Program pays registered hunters to remove pythons from state-managed lands, and the annual Florida Python Challenge draws hundreds of participants each year. These efforts remove thousands of snakes but represent only a small fraction of the total population. The consensus among biologists is that current removal methods cannot eradicate the species from the Everglades. They are valuable for reducing local python density in targeted areas, gathering data on python biology, and keeping the issue in the public eye, but they are not a solution in themselves.
Citizen science plays a role as well. Florida’s IveGot1 platform, developed originally through the Everglades Cooperative Invasive Species Management Area, allows professionals and members of the public to report sightings of invasive species via a website or smartphone app. By mid-2015, users had submitted thousands of records through the system, and it has become a national model for invasive species reporting and early detection.19Southeastern Naturalist. IveGot1: Reporting and Tracking Invasive Species in Florida
The Economic Side of the Invasion
Putting a dollar value on ecological damage is never straightforward, but one analysis attempted to estimate the cost of python predation on protected wildlife. Using the wood stork as a case study (a federally listed species at the time), researchers estimated that a single python successfully preying on wood storks could generate losses of roughly $6,500 per month and nearly $78,000 per year, measured against the public investment in stork recovery programs.20Endangered Species UPDATE. Reptilian Pathogens of the Florida Everglades: The Associated Costs of Burmese Pythons Florida’s fines for releasing a Burmese python into the wild have been tightened over the years, but the regulatory costs still may not reflect the true ecological damage a released animal can cause over its lifetime. The broader economic effects of the invasion, including impacts on ecotourism, sport fishing, and the fur trade (raccoon and opossum pelts were once commercially harvested in south Florida), remain harder to quantify but are real.
What Visitors Should Actually Expect
If you visit Everglades National Park, you are far more likely to see native water snakes, racers, or a cottonmouth basking on a canal bank than you are to spot a Burmese python. Pythons are largely nocturnal and extremely difficult to see in the wild, even for trained biologists with radio-tracking equipment. Most visitors spend days in the park without encountering one. The native snakes, on the other hand, are a normal and healthy part of the ecosystem. A cottonmouth sunning itself near a boardwalk is doing exactly what it is supposed to do, and it will almost always move away if given room.
For hikers and kayakers, the practical advice is simple. Stay on marked trails, watch where you step and put your hands, and give any snake you see plenty of space. Venomous snakebites in the Everglades are rare, and no visitor has been attacked by a python. The snakes that make the Everglades ecologically interesting, both native and invasive, are overwhelmingly uninterested in human beings. The real drama of the Everglades snake story is ecological, not personal: a slow-motion collision between a spectacularly rich native reptile fauna and an invasive predator that has already changed the landscape in ways that will take decades to fully understand.