The Key Largo woodrat and cotton mouse were already endangered. Then came pythons.

When the Key Largo cotton mouse and woodrat were placed on the Endangered Species List in 1984, federal scientists named several factors that were imperiling the rodents’ existence. Most serious was the loss of habitat due to development.

Not mentioned were Burmese pythons, feral cats or black and white tegus, a species of omnivorous reptile native to South America that has gained a foothold from Florida City to about halfway down the 18 Mile Stretch of U.S. 1 leading to the Florida Keys. But in the 35 years since the woodrat and cotton mouse became federally protected, those three predators have become major obstacles to them shedding their endangered status.

The U.S. Fish and Wildlife Service this week released draft recovery plan revisions for 42 endangered species including three species found only in the Florida Keys — the woodrat and cotton mouse, as well as the Schaus’ swallowtail butterfly, which used to thrive in the tropical hardwood hammocks in the Miami area, but is now found only in a few areas in Key Largo.

In order for the cotton mouse and woodrat to be taken off the endangered list, federal scientists propose a series of steps that must happen first. These include the emergence of clusters of the rodents living in five new locations other than the two places where they are found now, the Dagny Johnson Botanical Preserve State Park and the Crocodile Lake National Wildlife Refuge, both in Key Largo.

Also, the populations of Burmese pythons, feral cats and tegus in the area must be significantly reduced.

While tegus have not been found in Key Largo in the large numbers that they have in Florida City, the FWS maintains they are a threat to the cotton mouse and woodrat, as well as other native species, because they are omnivorous and “highly intelligent, capable of running at relatively high speeds, and known to consume small vertebrates,” according to the draft plan.

Meanwhile, federal officials theorize there’s a connection between the growing numbers of pythons and feral cats: cat food.

Jeremy Dixon, manager of the Crocodile Lake National Wildlife Refuge, has long urged people in the Upper Keys to stop feeding feral cats because they prey on the cotton mouse and woodrat.

But there’s another problem with leaving cat food out on the street and in the woods: It attracts other animals, like racoons, opossums and invasive black rats, and those species all attract Burmese pythons, which eat them, Dixon said.

Given the high number of feral cats and the people who feed them, “I honestly can’t think of a better scenario for increasing python numbers,” he said Friday.

Pythons became a South Florida problem about 20 years ago after people released what were likely pets that became too large into the wild and they took to the warm, wet climate.

Dixon said the woodrat populations are improving in some areas within the refuge, but not ones near neighborhoods, “presumably because of the numbers of feral cats that spill over into conservation lands.”

No tegus have been detected in the refuge, Dixon said.

The refuge has a volunteer “Python Patrol” where people can search for the invasive snakes in the Crocodile Lake area and other conservation lands in the Upper Keys. Those wanting to participate can call (305) 451-4223 or email crocodilelake@fws.gov.

“Additionally, we’ll be participating in several projects in the coming years that are designed to better detect and remove pythons from conservation lands,” Dixon said.

If you see a python, call 888-IVE-GOT1. Dixon said to also stay with the snake until an officer with the Florida Fish and Wildlife Conservation Commission arrives to remove it.