Pythons in the Everglades: Frequently asked questions
Caption-Biologist Ed Metzger with a 18'3" 133 lb Burmese python
Giant snakes in the glades? What's the story?
Burmese pythons are native to Southeast Asia, but are now an invasive species in south Florida. These large snakes were imported by the thousands for the exotic pet trade, many being bought by owners with little knowledge or regard as to how big the snakes grow and the responsibilities and care such an animal requires. People would buy a hatchling python as a harmless baby, but the snake would quickly grow to a large size with an equally large appetite, so that many people were no longer able or comfortable to care for it. They then released the snakes into the everglades. A large snake can be very difficult to handle, properly house, and properly feed. In the past, there was no permit or experience required to buy one; anyone could walk into a pet store and buy a snake that could one day reach 20 ft. in length. While I was in college there were no laws or permits restricting the ownership of large constrictors and I was approached by a student who lived in the same dorm building, wanting to show me a baby anaconda he had just bought. He knew I was knowledgeable about reptiles and asked advice on how to care for the baby anaconda, as he said he had no idea how to care for it and bought it because "it'll impress chicks". I have no doubts that that snake either died from improper care or was released into the everglades.
Another proposed genesis point of pythons is hurricane Andrew, a massive category 5 hurricane that caused immeasurable damage in south Florida and released many exotic animals when caging and housing was destroyed.
Other possible points of introduction include people purposefully releasing snakes to start a colony to create their very own zoo-like landscape in south Florida, or because they like the animal and wanted to see it here. This may sound far-fetched but it is actually the origin story of several introduced species such as European starlings and Brazilian pepper.
Caption-An 8ft python on an everglades levee
How big do they get?
Burmese pythons are often listed as the third longest snake in the world, with reticulated pythons being longest, followed by the green anaconda (although this list is often hotly debated with unverified claims and assertions of huge snakes with little evidence). A quick Google search will often yield varied and contradicting answers, but the longest verified Burmese python was a captive animal which measured 18' 10" named Baby. Most 20 ft. claims can be traced back to this individual. However, there have been a handful of 18 ft. individuals removed from the Everglades so far and I have no doubt that someone soon will make the headlines with a 20 footer.
Caption-Biologist Ed Metzger with a 18'3" 133lb Burmese python
Are they going to eat people? Pets?
Burmese pythons will eat pets, absolutely. People, not so much. There have already been several pets documented as meals for wild pythons, which honestly should not surprise anyone in a state where large reptiles regularly consume our furry friends (dogs and gators don't mix!). As far as the danger to humans extends, it is highly unlikely for a wild python to attack and kill a human that is out minding their own business. You would be more likely to be struck by lightning, multiple times, than to be attacked by a wild python. BUT large pythons are potentially dangerous and there have been several instances of captive pythons killing their owners. This happens when the snake develops what is called a "feeding response". The snake learns that when their enclosure door opens, sometimes food is thrown in. A hungry snake will then begin to anticipate that whatever comes through the open door is likely to be food(yes, they are smart enough to learn patterns and to anticipate things, as are goldfish). Some snakes will even have a feeding response to their owner merely touching the enclosure or walking by in a way that is indicative of possibly opening the door. This is where it is very important to point out that this response is NOT a normal predatory/hunting response but instead a learned behavior. The snake is not hunting the person specifically, but instead it has learned that when the door opens food comes through and so bites at the anticipated "food", which might end up being the person. This is a very important distinction to make. Once the snake is shown that it is not being fed in this moment it can then safely be handled without trying to bite. An example of this is that I once worked with a 20 ft. reticulated python with a very severe feeding response. It was one of the scariest animals I have ever worked with, and would try to feed upon anything that touched the enclosure door, but once taken out it was fine and tame. This is why large snake species should never be kept by novices. Some snake owners also think their snake "likes" them and would never hurt them. Unfortunately, these anthropomorphizing owners are very sadly mistaken. Whether by inexperience, ignorance, or stupidity, the person who puts their hand into the enclosure of a large constrictor with a feeding response could be in for a very unfortunate experience that could potentially even result in death. My point of explaining this process is to illustrate that most deaths from pythons reported in the media are actually due to the folly of captive keepers, not of the snakes hunting people down. To my knowledge there is not a single verified human death from a Burmese python in the wild, although there are a few from reticulated pythons. As for the wild pythons in Florida, I don't think anyone should be worried about being attacked or having giant snakes climbing through their windows. The threat they pose to humans is astronomically small.
Caption- A wild python striking out.
What makes them so successful here?
Pythons are very successful in south Florida for a variety of reasons. A female python can lay over a hundred eggs per clutch and the young hatch out just under 2 ft. in length, which is the adult size of some of our native snakes here in Florida. They can grow to a large size rapidly, up to 6 ft. in their first two years of life, allowing them to outgrow most of our native snake predators and opening a much wider selection of large prey. With a lack of predators, an abundance of prey, and a high reproductive rate, python numbers were able to explode in Florida.
Caption- A clutch of wild python eggs in a culvert pipe in the everglades.
Pythons are also habitat generalists and make themselves at home in marshes, pine rocklands, mangroves, and other Florida habitats. They can be very aquatic and are adept swimmers, seeming to use canal systems to help in their spread.
Caption- A young python swimming in the everglades.
Caption- A python is at home in the aquatic everglades.
How real is the threat to the environment?
The threat of wild pythons to people is highly exaggerated and sensationalized by most media outlets, but the threat this invasive species poses to the surrounding environment is very real. The effects of the presence of an apex predator can be wide ranging, diverse, and unpredictable. An incredible and well studied example of just how extensive the effect one species can have on an environment is the story of wolf reintroduction in Yellowstone, where the presence of wolves influenced grazing behavior and altered the course of rivers and changed habitats. You can learn about the Yellowstone wolf story here https://blog.ted.com/video-how-wolves-can-alter-the-course-of-rivers/
But what do wolves have to do with snakes? The wolves are an example of how one top predator can influence the behavior of prey and literally change the habitat and landscape. We currently have no idea if or how pythons are influencing the behavior of alligators, birds, or any of their other prey, and may not be able to see the cascading effects for decades. In a hypothetical situation pythons could cause major changes to how the everglades functions, or could have no effect, but due to how complex ecosystems are there is no way to know.
Caption- A hatchling burmese python
So let's leave the hypotheticals behind and explore what we DO know- pythons have been recorded to eat an extremely long and varied list of native wildlife, ranging from 6ft alligators(reread that- SIX FOOT long gators, not just little babies!), adult deer, bobcats, raccoons, opossums, and a wide variety of wading birds. The list goes on and on to include just about anything smaller than deer and gators. This list also includes many protected or endangered animals such as the Key Largo woodrat, wood stork, mangrove fox squirrel, and others.