The Burmese python problem: how 20ft predators are wreaking havoc on the Everglades

There are between 100,000 and 300,000 of these snakes in the region – and they can swallow a small deer whole. What can Florida do about this threat to biodiversity?

An invasive predator that can grow up to 20ft, weigh over 100kg and devour prey six times its size – it is enough to make anyone’s skin crawl. That’s what residents of southern Florida have been struggling with for the past few decades, with the rapid growth of the Burmese python population in the Everglades.

In a recent study in Reptiles and Amphibians, a team of researchers considered the maximal gape of three Burmese pythons – in other words, they measured how wide the snakes could open their mouths. The smallest of the pythons had been found consuming a 35kg deer. So perhaps it isn’t surprising the researchers discovered that all three snakes had impressive maximal gapes of 26cm (10 inches), 1.5in wider than previous studies had suggested and similar to the diameter of a standard dinner plate.

There are no other apex predators in the Everglades region meaning these invasive pythons, with their insatiable appetites, are wreaking havoc on one of America’s biodiversity hotspots. A study from 2012 found native populations of raccoons, opossums, and marsh rabbits had been all but wiped out since 1997.

Tales of how the species (full name: Python molurus bivittatus), which is native to Southeast Asia, came to be in Southern Florida include a compelling one of a dark and stormy night. When Hurricane Andrew - a category five storm still considered among America’s most costly - hit Miami in 1992, one of the buildings destroyed was a reptile breeding centre. According to a 2009 New Yorker interview with an official, escapees from the centre included hundreds of juvenile Burmese pythons.

But as dramatic as this is, a study from 2011 also concluded, less cinematically, that the release of a relatively small number of snakes - likely, pets - prior to 1985 played a role. While sightings of individual snakes in the region go back to 1979, it wasn’t until the late 1990s that a reproducing population was established and numbers exploded.

So why did owners release their once-adored companions into the wild? Hatchling pythons are only 22 inches long but can grow to nine feet by the time they are five years old. It’s around this age that pythons reach sexual maturity, with females producing up to 100 eggs annually.

Recent estimates of the population by the Florida Fish and Wildlife Conservation Commission (FWC) put the number of Burmese pythons anywhere between 100,000 to 300,000. But those numbers are being chipped away by various schemes.

As well as a nationwide import ban, since 2017 the Python Elimination Program in Florida has paid a handful of vigilante residents to “humanely euthanise” pythons, with size-dependent commissions paid on top of an hourly rate. An annual competition - the Python Challenge - also offers up to $30,000 (£23,582) in prize money for amateur hunters who compete over a 10-day period.

Other approaches include training a beagle, known as Python Pete, to sniff them out, and using a tagged male snake to reveal the location of a reproductively active female.

Combined, these efforts are making a dent. A recent estimate by Rodney Barreto, Chairman of the FWC, claimed 14,000 pythons had been “successfully removed” since 2017.

The US Geological Survey (USGS) says “controlling their numbers and preventing their spread out of the area are critical goals for conservation efforts and land managers.” But the odds of eradicating an invasive species like this completely is very low.

Thankfully for the area’s human residents, the risk of attack by Burmese pythons, according to the USGS is also “very low”, with no recorded deaths by pythons living in the wild. Their advice: “avoid interacting with a large constrictor.”

Cover photo: A Burmese Python with mouth open. Recent research has found that their maximal gape is 1.5in wider in diameter than previously thought. Photograph: Hillary Kladke/Getty Images