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No jolly Disney ending for endangered Key Largo wood rats bred at Animal Kingdom

Disney raised endangered Key Largo wood rats, like this one at Lowry zoo, but they don’t survive long in the wild.

Lowry Park Zoo

Disney raised endangered Key Largo wood rats, like this one at Lowry zoo, but they don’t survive long in the wild.

Ten years ago, in a desperate move to save one of Florida's most endangered species, U.S. Fish and Wildlife officials approved capturing a few of the animals and taking them to Tampa's Lowry Park Zoo for captive breeding.

The endangered species in question was not the Florida panther, the manatee or any of the other license-plate icons that call the Sunshine State home. It was the Key Largo wood rat, a small rodent with cinnamon fur and bulging black eyes.

Federal officials figured they could save the species from extinction by spending $12,000 a year breeding the rats and then turning them loose again in the wild.

At first the breeding program seemed to be a big success. At Lowry Park and, later, Disney's Animal Kingdom, the endangered rats bred like, well, rats. But then the project ran into big problems, demonstrating why captive breeding is a tricky strategy that's used only as a last resort, said Larry Williams, South Florida field supervisor for the Fish and Wildlife Service.

The rat project ended this spring, he said. The shutdown "was a little disheartening for us," said Anne Savage, senior conservation biologist for Disney's Animal Kingdom. Perhaps it is no surprise, given the role of a cartoon mouse in Disney lore, that Animal Kingdom won a national award for its success in breeding the rats.

The effort did yield some important scientific discoveries, including a disquieting one about Florida's most notorious invasive species.

• • •

Key Largo wood rats have been classified as endangered since 1984. They build nests out of sticks in hardwood hammocks of mahogany, wild tamarind, black ironwood and pigeon plum, most of which have been bulldozed for homes and other development on the key south of Miami.

Their last refuge was, in fact, a refuge: the Crocodile Lake National Wildlife Refuge and, next door, the Dagny Johnson Key Largo Hammocks Botanical State Park, which cover more than 8,000 acres.

But the population kept plunging. One estimate said only 50 were left. Wildlife biologists didn't have to look far for the reason.

Next to the parks is the Ocean Reef Club, a gated community that boasts some of South Florida's wealthiest residents — as well as the state's largest feral cat population. Ocean Reef's homeowners spend thousands of dollars a year on a program that feeds and cares for the stray cats that wander the back alleys — and, according to biologists — occasionally gobble up endangered rats.

By 2002, the situation had become so dire that federal officials approved trapping some of the remaining rats and turning them over to Lowry Park Zoo for captive breeding. Disney's biologists were brought on board in 2005.

Breeding the rats wasn't as easy as it might seem. They are nocturnal animals, so biologists eager to learn about rat behavior had to watch them at night.

They also tend to be solitary. The males and females only get together when the female is ready to breed. Put them together any other time and they fight, Savage said, comparing it to the movie He's Just Not That Into You.

But the first rats were born at Lowry Park Zoo on Mother's Day 2003, and dozens more followed.

In 2009 Disney won a prestigious national conservation award from the Association of Zoo and Aquariums for its breeding work. It even turned the program into part of the Animal Kingdom tour. Children could don a chef's toque and become "Chef Remy," the gourmet star of Ratatouille, and put together a meal for the wood rats (leaves, buds, seeds and fruits).

What the children couldn't see was that even a successful breeding program has limits.

"We were at the point where we needed new genetic material," Savage said. Without catching some more wild rats, the captive colonies would begin inbreeding, which would lead to genetic defects.

But things weren't going too well out in the wild.

• • •

Disney set up an intensive study of how the wild wood rats behaved in their native habitat. They put radio collars on some of the wild rats and followed them around to learn how they ate and nested. But when they began releasing the radio-collared, captive-bred rats in 2010, the rats didn't last long.

"The feral cats were just wiping them out," said Darren Wostenberg, one of the biologists who followed the rats' radio signals. "We released 14 the first time out and within a week we'd lost half of them. They weren't used to predators."

The wildlife agency decided to try something different. In December, the last 15 of the captive-bred rats were turned loose on nearby Palo Alto Key. No wood rats live there, but neither are there any feral cats.

"Each individual was radio tagged, as the plan was to track them for at least four months," explained Fish and Wildlife Service spokesman Ken Warren.

Within a month, nearly half were dead, gobbled up by owls and other predators from the skies. At the end of four months, only three remained. In May, when they were down to just one male on Palo Alto Key, biologists recaptured it and took it over to Crocodile Lake. They hoped it would find the wild rats and reproduce.

But the rat somehow slipped out of its collar. "His fate is unknown," Warren said.

The project wasn't a total loss. Sullivan pointed out that biologists now know far more about rat behavior than ever before. They discovered captive-bred rats have to learn how to avoid predators, unlike other species that have an instinct for dodging death.

And they learned something about a predatory species. In 2007 a biologist following the signal for one of the captive-bred rats came face to face with a 7 1/2-foot Burmese python. Although the invasive snakes are a widespread menace in the Everglades, this was the first python found in the Keys, showing that pythons apparently can swim.

The radio tracking device, and the rat wearing it, were both inside the snake.

Craig Pittman can be reached at

No jolly Disney ending for endangered Key Largo wood rats bred at Animal Kingdom 07/08/12 [Last modified: Sunday, July 8, 2012 7:58pm]
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