The Crocodile Lake National Wildlife Refuge in Key Largo, Fla., is home to two endangered rodents: the Key Largo cotton mouse and the Key Largo woodrat.

With about 1,000 cotton mice and fewer than 100 woodrats remaining, refuge staff are cracking down on potential threats to the animals — including cats.

Felines caught in the refuge will soon be trapped and their owners fined.

"The first time we capture a cat, we'll give the owner the benefit of the doubt with a warning," Jeremy Dixon, refuge manager, told The Keynoter. "The second time could mean a fine of $175, and could include a mandatory appearance in federal court."

Mike Cove, a wildlife biologist, uses sensor-triggered remote video cameras to gauge whether manmade nests placed by staff are being used by the endangered rodents.

His video footage proves that the artificial habitats are used by the animals, but it also shows felines making visits to the nests.

In 2013, he recorded 284 nests and taped two cats. So far this year he's recorded seven cats at the first 54 nests.

Since 2010, the staff have captured 84 cats on the 6,600-acre refuge.

While woodrats and cotton mice fall prey to native predators like snake and owls, Cove says the cats present a unique challenge.

"The problem is that cats are not supposed to be there. As a result, the woodrats are predator-naive about a predator that is a rodent specialist."

Refuge staff plan to start trapping cats on the land and taking them to the Upper Keys Animal Shelter for identification through tags or microchips. Cats that aren't identified will be put up for adoption.

However, the shelter's director told the Sun Sentinel that feral cats ineligible for adoption will likely be euthanized.

David Ritz, administrator of the Ocean Reef Club, a community north of the refuge, said he doesn't support the trapping campaign.

His community is home to a population of about 500 cats. The number has been reduced from 1,500 through a local trap-neuter-return program.

"We're opposed to catching and killing cats," he said. "If they have a problem with feral cats, they ought to start catching them and neutering them and moving them away from endangered animals."

The Fish and Wildlife Service has promised to return any cats bearing the tattoo given to spayed or neutered Ocean Reef cats.

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