In late November, biologists and members of the public released black-footed ferrets at two sites Wolf Creek in Colorado and Snake John Reef in Utah.
The ferrets released will do more than increase the size of ferret populations. They may help biologists develop a vaccine that will protect ferrets from sylvatic plague.
Similar to black plague in humans, sylvatic plague can wipe out a ferret population.
"The 10 ferrets released into Snake John are part of a larger study to determine the effectiveness of a vaccine developed for the sylvatic plague, which is the prairie dog version of the black plague," said Brian Maxfield, sensitive species biologist with the Utah Division of Wildlife Resources.
"The black-footed ferret preys almost exclusively on prairie dogs, so large colonies of prairie dogs are essential to the ferrets. Unfortunately, neither the ferret nor its prey have natural immunities to the plague."
The Utah and Colorado sites are two of four sites that a biological team working for the U.S. Geological Survey have designated in the vaccination study.
"The study started in 2004," said Maxfield. "As part of the study, we get about 20 animals a year. The vaccine is given to half of the animals. The other half are control animals that are not vaccinated.
"So far, it looks like a success. We know we have plague at low levels in the Utah-Colorado area, but there hasn't been a serious outbreak at these release sites."
He said the best information about plague comes from a plague outbreak in prairie dogs at the Charles Russell National Wildlife Refuge, a ferret reintroduction site in Montana.
"Part of the ferret colony died, but it seems like the vaccine saved most of the ferrets that were vaccinated," he added.
In addition to the vaccine study, the ferrets released at Snake John will help the overall reintroduction efforts in the area.
The released ferrets in the Snake John area will help supplement a small, wild ferret population.
In the 16 or so colonies of prairie dogs in the Snake John area, ferrets have been found in four.
According to reports, the black-footed ferret was the last mammal discovered on the North American continent. These small members of the weasel family are nocturnal and live most of their lives underground inside prairie-dog holes.
Ferrets weren't rediscovered until 1981, when a rancher took an unusual animal his dog had killed the night before into a small store in Meeteetse, Wyo.
From 1981 to 1985, this small population expanded to 129 animals. Then, in 1985, the population crashed when distemper and the plague ravished the ferrets and a colony of prairie dogs the ferrets were preying on.
The black-footed ferret quickly became the most endangered mammal on earth. Biologists collected the last 18 known animals between 1985 and 1986 and began an emergency-breeding program. At first the breeding program failed because most of the ferrets were too young to breed successfully.
Fortunately, the last ferret collected was an older male who knew how to breed successfully.
Today, six breeding facilities produce roughly 300 to 350 kits or baby ferrets per year.
In the late 1980s and early 1990s, Utah began mapping prairie dog colonies in the state. After the colonies were mapped, two areas were identified as potential reintroduction sites for black-footed ferrets the Cisco Desert and Coyote Basin.
When an outbreak of plague hit the Cisco prairie dog population, Coyote Basin in northeastern Utah became the state's primary release site.
At the same time, similar sites were also being identified in Colorado.
In the fall of 1999, 71 ferrets were reintroduced into Coyote Basin.
Later that winter, biologists conducted a survey. They found only half a dozen ferrets. And they found only two ferrets during a survey the following spring.
The following year, biologists found nine adults and three kits, which showed reproduction.
In the fall of 2000, another 67 ferrets were reintroduced to the area. Between 1999 and the most current release in November 2007, 313 ferrets have been reintroduced into Coyote Basin and the surrounding area of Snake John.
To successfully bring an animal that was once considered the most endangered mammal on earth back will depend not only on raising and releasing animals from captive facilities, but also on protecting and enhancing prairie dog colonies and reintroducing ferrets to new sites.
• Brighton Ski Resort will hold what it calls "Quad" Wednesday on Dec. 19.
Skiers and snowboarders will be able to buy an area day pass for $14 with the donation of one full grocery bag of non-perishable food. No cash or check donations will be accepted.
All donations will go to the Utah Food Bank. For information call 801-532-4731, est. 220.Earlier this month, Brighton held events for Toys for Tots and the Road Home Homeless Shelter.