Pythons become the prey: Florida predators are fighting back against the snakes

Bill Kearney, South Florida Sun-Sentinel
·6 min read

Massive invasive pythons kill deer, bobcats, otters, racoons, possums, rats, even alligators — pretty much anything that unwittingly ambles within striking distance. The problem is so severe that in some areas, mammal populations have dropped by 90%. But now there’s proof that some of those animals are fighting back.

Though Florida’s largest pythons — which have grown to 19 feet — are probably too big for anything other than a human to tackle, the babies are a different story.

Recent studies prove that juvenile pythons are on the menu for quite a few native Florida predators, and probably fall prey to a range of species.

For clues on what eats them, biologists look to their native range, southeast Asia, where eagles and Bengal monitor lizards have been documented killing similar snakes, the Indian rock python.

Here in Florida, baby pythons hatch in early summer and are already 17 to 31 inches when they slither out of the nest — larger than most of Florida’s native snakes, according to Ian Bartoszek, wildlife biologist at the Conservancy of Southwest Florida. They’ve got a head start on the ecosystem.

To understand more, and better calculate how many pythons actually live in Florida, researchers from the U.S. Geological Survey and others, including Bartoszek, have surgically radio-tagged hatchling pythons and tracked them in and around Big Cypress Preserve.

Each tag had a mortality sensor that pinged if the snake stopped moving for 24 hours. Once researchers heard the death ping, they immediately trudged into the wilderness like a swampy CSI crew, to conduct detective work: Were there predator prints in the mud, any disturbed vegetation, fur, scat, blood, stray scales? Or, if the snake’s body was still there, were there telling wounds? How far apart were the fang punctures, how large the claw marks?

What eats them

Of the 19 hatchling snakes that died in the USGS study, researchers were able to decipher the cause of 12 of the deaths, and the others had intriguing clues, but not enough information to fully confirm what happened.

Five of the snakes fell to alligators. How did they know? Alligators swallow prey whole, so when they honed in on the transmitters, they found well-fed gators — the transmitters were in their stomachs and would move whenever the gators did. Most of the gators were 4 to 5 feet long, but one was a bruiser, at 9 feet.

Cottonmouth snakes snagged three of the pythons.

Cottonmouths, aka water moccasins, are thick, 2 to 4 feet long, and venomous. Unlike pythons, they’re not constrictors. In any case, they were able to overpower the lighter pythons. Like gators, they swallow prey whole, so researchers found them with trackers in their bellies.

One baby python met its match while preying on a cotton rat that outweighed it. Researchers found the snake dead with a huge lump in its belly. Though it was able to subdue and swallow the rat, apparently there was quite a battle. The snake had several deep bite marks; one punctured the stomach and the other may have punctured a lung.

“Invasive species in new environments might not have behaviors that are well-suited for that environment,” wrote USGS biologist Mark Sandfoss in an email. “This can lead to … behaviors that are potentially lethal, as the case with the cotton rat. Put plainly, the snake did not recognize the cotton rat as a dangerous prey item and, instead of avoiding it, the snake attacked and ended up being killed.”

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Researchers attributed three kills to cats of some sort. They found a chewed up tracker with footprints nearby from either a young bobcat or a feral cat. Another chewed up tracker had vomited hairballs near it — a sign of cats. The third kill, with a tracker and half-eaten python carcass, had cat tracks nearby.

Mystery deaths, intriguing clues

Seven of the python deaths were “unattributed” without enough conclusive evidence to name a killer. But there were signs that the snakes were eaten; one carcass was stashed away along a mammal trail. And in two instances, researchers found the trackers removed from the snake’s bodies and in curious places that hinted at death by hawk or owl.

One tracker was in a flooded area with perfect owl and hawk perches above. They found another tracker hanging five feet off the ground in prairie grass near cypress trees, where hawks could overlook the area.

In the USGS study, reptiles enacted 72% of the python killings, possibly because their semi-aquatic habitats overlap so much.

In addition to gators and cottonmouths, Bartoszek’s studies documented the endangered eastern indigo snake and black racer snakes dining on juvenile pythons, and others show American crocodiles doing the same.

Mammalian revenge

A USGS paper cataloging years of python data points out that other native mammals make a habit of eating snakes, and might therefore find baby pythons appetizing.

They include some victims of larger pythons, including river otters, Everglades mink, coyote, raccoon, gray fox and possums. Researchers also have found an adult python ripped open by a bear, which may have been defending itself, as it didn’t eat the snake.

It’s possible that Florida panthers might kill them as well, and large pythons compete with panthers for key prey, the white-tailed deer.

Danger for yearling pythons could also come swooping down from the sky in the form of native swallow-tail kites, red-shouldered hawks, red-tailed hawks, ospreys, or stalking along the shoreline from great blue herons, white ibises and wood storks.

Even other invasive animals could get in on the baby python action, including feral hogs and Nile monitor lizards.

Monitors and Argentine tegus could raid their nests as well. Outside the study, the USGS has some amazing camera trap footage of a young bobcat sniffing out a clutch of eggs, coming back to face off with the massive momma snake, then returning when she’s gone to eat a few eggs.

Though juvenile pythons are small enough for all these animals to kill, the window of opportunity to eat them is brief. They can grow exceptionally fast. Bartoszek has seen them reach 7 feet in a year, and has found a 10-pound python with a baby white-tailed deer in its stomach.

Females typically lay 18 to 84 eggs once a year. How many can survive the gauntlet of predators? There’s not much research, but Bartoszek conducted a study on 28 hatching from four nests and found that 28% survived to the first year, and two snakes, or 7%, survived to two years.

Those that survive do immense damage to Florida’s ecosystems. “One of the impressive, and in this case devastating abilities of snakes is to take down prey items that are of much larger body size than them,” wrote Sandfoss. “There are many examples of snakes, including pythons, eating food items that weighed more than themselves.”