Sunday, 1 February 2015

Rock python might hold clues in Florida about invasive snakes - Herp Digest

Edward Mercer stood on a dirt road at the edge of the Florida Everglades on Thursday, reached into a white sack, pulled out another sack and then, like a magician reaching into his bag of tricks, produced a 10-foot long Northern African python for a bank of television cameras.
A sister species to the Burmese, the Northern African or rock python has gotten a toe-hold in a six-square mile area west of Miami. Unlike the Burmese, rock pythons have so far stayed put since first appearing in 2001.
And that has state wildlife officers like Mercer taking a closer look at them. If the state can maintain control or even wipe out the snake entirely, it might just have a shot at curbing the more indomitable Burmese, which can grow to jumbo proportions.
Since turning up in 2000, the Burmese python has become the face of South Florida’s losing battle against invasive species, blamed for wiping out small mammals in Everglades National Park and even causing a decline in wading birds. While the Burmese has spread across hundreds of miles — recent sightings south of Lake Okeechobee suggest it is staking out new territory — the rock python has largely stayed in the small remnant marsh and nearby neighborhoods just east of Krome Avenue, under the watchful eye of state wildlife officers.
“It’s a big deal to have a success story and say we did it,” said Brian Smith, a University of Florida research assistant. “We just need to do it again” with the Burmese.
The state will not declare a victory until surveys find no rock pythons for five years, said Florida Fish and Wildlife Conservation Commission biologist Jenny Ketterlin Eckles. So this year, the state officials expanded efforts, hiring Mercer as the first and only rock python hunter and increasing surveys. They hope to draw more attention to the rock and, by proxy, the Burmese.
Biologists don’t know how the rock python found its way to the area. But like the Burmese, they believe the first snakes were probably escaped or released pets. The state made rock pythons illegal to own in 2010. Two years later, the federal government banned importing them. The snakes remained mostly under the radar until a 10-footer strangled a Siberian Husky as its owner and her son fought to pull it off two years ago in a nearby neighborhood.
Only 29 have been captured since 2001, and none since the 2013 dog attack. Three more were found dead, Ketterlin Eckles said. Altogether, only 37 rock python incidents have been recorded — either captures, recovered carcasses or sheds, or sightings, state records show.
But not seeing the snakes is not proof of their absence, although Ketterlin Eckles said the state has no way of knowing how many there are. Like the Burmese, rock pythons have a giraffe-like brown, black and tan pattern. The easiest way to tell them apart is to roll them over: Burmese have plain white belly scales. The rock’s belly is speckled with black.
Both are ambush predators, so camouflage is their currency. And like so many others before them, South Florida swampland has made them rich, with its tangle of high grasses and shallow marshes. Stories of the Burmese’s ability to hide are legendary. Liz Barraco, who runs FWC’s pet amnesty program, said state wildlife officers trying to find a wood rat tagged with a tracker once walked in circles after they located the tracker but no wood rat. Finally they realized the rat was inside the belly of a Burmese python hiding beneath their feet.
Snakes hiding in just a few inches of marsh water will remain still even when stepped on, Smith said.
“They’re so confident they’re hidden,” he said.
Biologists say they know little about the Burmese, so even less about rock pythons.
Rock pythons might not be spreading because they’re not good swimmers, unlike their cousins from Southeast Asia, which can submerge themselves for about 30 minutes. Or they might simply be biding their time for the right event to trigger an explosion, said Frank Mazzotti, a UF wildlife ecologist.
“We really don’t know, so that’s why it behooves us to focus on them while [the population] is small and localized,” he said.
But wildlife officers assume the species share enough traits for the study of one to inform the other. And the one mystery the hope to unlock on both is how to detect them. Currently, biologists only have a 1 percent detection rate of Burmese. That probability needs to be at least 50 percent, Mazzotti said.
“There can’t be any controls unless we can wrestle the detection issue,” he said.
Most live pythons, both rock and Burmese, are found basking on canal levees after a cool night, or warming themselves at night on roads heated by daytime sun. The state has been running its rock python surveys since November and will continue through April until warmer temperatures mean the snakes can stay undercover. When snakes are found, they are euthanized, Ketterlin Eckles said.
While that ground war effort is important, Mazzotti said biologists need to find a bigger solution.
“We’re not going to win the war until we develop the atom bomb,” he said.
And so far, nothing has worked on the Burmese. Using pheromones was dismissed because it only attracted male snakes. A judas snake tagged with a tracker to lead wilidlife officers to a nest could expose breeding colonies, but would only locate a few at a time since most breeding groups average about seven males and one female, Smith said. Dogs have been trained, but South Florida’s withering heat interfered with their ability to pick up scents.
For his thesis, UF’s Smith is attaching GPS trackers to snakes, hoping to detect a pattern to their movement and determine whether it’s related to weather or time. Everglades National Park is also trying to detect pythons by testing marsh water for their DNA, Ketterlin Eckles said.
Meanwhile the stakes keep getting higher. New research suggests that nesting wading birds are attracting pythons.
“They keep finding pythons in wading bird rookeries, so that’s a new problem,” Mazzotti said.
Mercer, a former graphic artist who moved to Florida with seven pet pythons before becoming a volunteer in 2010, says he looks for three things when hunting the giant rock pythons that can grow to 18 feet but average six to nine feet in Florida: the right vegetation where they can hide, a food source like wading birds and nearby water they use as an escape route.
“Catching them is easy,” he said. “It’s finding them that’s difficult.”

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