(CNN) -- There were no snakes on the floodplain for Drew Reisinger, one of hundreds of people who trooped into the Everglades over the weekend to hunt Burmese pythons.
"We saw hundreds of gators and beautiful migratory birds, but no pythons," said Reisinger, who spent his weekend poking around Big Cypress National Preserve with about a half-dozen old buddies.
Florida's Fish and Wildlife Conservation Commission launched its month-long "Python Challenge" on Saturday, hoping to get rid of some of the tens of thousands of invasive snakes that have found a home in the River of Grass. Nearly 800 people, lured by prizes of up to $1,500, have signed up to hunt down the pythons in cold blood.
But only 11 Burmese had been bagged by Monday afternoon, agency spokeswoman Carli Segelson said.
State wildlife officials say there may be as many as 100,000 Burmese pythons living in the vast swamps outside Miami. By comparison, the state is home to about 1.3 million alligators.
"You can go out there for days and days and days and not see one python," snake hunter Justin Matthews said. "I don't care how much experience you have. It is going to take some luck."
Reisinger said the unseasonably warm weekend may have cut into the haul. He said he and his companions were shooting for "the coldest weekend we could find," hoping the reptiles would be in the open to soak up the sun.
Instead, weekend highs were around 80 degrees, well above normal even for south Florida.
"There's some stuff that was very hairy and hard to get through, and machetes were helpful," Reisinger said Monday after returning home to Asheville, North Carolina. Then there were sections of swamp "that were easy to walk through," but had their own hazards: "When you can clearly see gators 100 feet in front of you, it makes it more intimidating sometimes," he said.
The pythons began turning up in the Everglades in 1979, most likely abandoned by pet owners when the snakes got too big to handle. They have no natural predators and can reach lengths up to 18 feet.
Rabbits and foxes have disappeared, while raccoon, opossum and bobcat populations have dropped as much as 99%, researchers at Virginia Tech University, Davidson College and the U.S. Geological Survey reported in 2012. The U.S. Fish and Wildlife Service has banned the importation of Burmese pythons, along with three other exotic snake species and their eggs.
The great snake hunt could be a boon to scientists like University of Florida wildlife ecologist Frank Mazzotti, who was preparing for a post-mortem on one python Monday morning.
"This is going to give us our largest single one-time sample, most snakes over the biggest area, that we have ever been able to collect," Mazzotti said. "And we're going to be able to ask questions about contaminants, things like mercury, genetics -- can we identify new individuals from the core population -- or diet, to help us address the very important question about what impacts these species have on our native ecosystem."
While the pythons can run to double-digit lengths, Mazzotti said the average snake runs about 6 to 9 feet.
State officials recommend shooting the snakes in the head or decapitating them with a machete. A grand prize of $1,500 will be awarded to the person who kills the most pythons, and $1,000 will go to the person who bags the longest one -- and no, roadkill doesn't count.
The contest wraps up February 16.
"I'm not a hunter. I'm not a herpetologist," Reisinger said. "I'm just more of someone looking for a good time and a chance to drink my beers with some buddies in the woods -- and if you can help the environment, too, that's great."
-- CNN's John Zarrella and Kim Segal contributed to this report.
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