Breeding isn't the only challenge. The survival plan also requires that captive-bred ferrets go to boot camp to increase their chance of survival.
Boot camp consists of a pen with special dirt where prairie dogs are introduced to dig custom burrows. The prairie dogs are removed and replaced with ferrets and the 60-day-old kits. The ferrets immediately take the babies into the dark burrows and they literally grow up in the hole. Kits that grow up in the burrows have a 10 percent greater chance at survival in the wild.
Then the prey is introduced. Black-footed ferrets eat only one thingprairie dogs. Kill the prairie dogs and you kill the ferret. This was actually the main trigger for their demise. In the 1920s and '30s ranchers tried to eradicate prairie dogs from grazing land because they believed they competed with cattle for grassland. Poisoning and sport shooting these animals is still legal in most states.
But prairie dogs are usually twice the size of a ferret, so at the breeding facilities ferrets are first trained to kill hamsters.
"If they can kill a hamster then we think it's safe to put a prairie dog in there. But the Fish and Wildlife regulations say that these animals have to kill a live prairie dog before they go for reintroduction or they don't go," said Howard.
Robot Badgers, Mechanical Eagles
There were also attempts to familiarize the animals with predators like badgers and eagles. A battery operated robotic badger on wheels covered in a real skin was rolled through the tunnels to simulate a threat. A swooping mechanical eagle was also used, but the ferrets quickly figured out the robots were fake and didn't run.
The ferrets are hardwired with instinct. They see a prairie dog and they know what they are supposed to do. They open their mouth wide enough to clamp down on the throat of a prairie dog, which is typically twice its size, and suffocate it, said Wisely.
Since 1987 nearly 4,000 ferrets have been bred in captivity, of which 1,400 have been released at eight sites, with the newest in Chihuahua, Mexico, said Paul Marinari, Fish and Wildlife biologist at the National Black-Footed Ferret Conservation Center in Laramie, Wyoming. Ferrets are fairly short-lived, with a life span of only 3 to 4 years in the wild and recent surveys reveal that the total wild population is somewhere around 300 to 350. The number could rise after the surveys in September and October.
Animals in the wild now outnumber those in breeding programs.
Currently the only self-sustaining black-footed ferret population is in Conata Basin/Badlands in South Dakota. Last year there were about 100 wild kits born herewe were actually able to skim off some of these and release them at other sites, said Marinari.
Before settlers arrived, scientists estimated that there were about five billion prairie dogs burrowing around in North America, and about five million black-footed ferrets, said Scott Weidersaul, naturalist and author of The Ghost with Trembling Wings, which devotes part of the book to the plight of the ferret. The animals ranged from northern Mexico to southern Canada and west of the Rocky Mountains through the Midwest grasslands.
The greatest challenge is finding a release site with a protected prairie dog population free of disease, especially sylvatic plaguethe animal equivalent of bubonic plague for which there is currently no vaccineand that is becoming harder to find. "At least in the foreseeable future black-footed ferrets will require ongoing, and intense management," said Weidersaul.
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