RUSSELL SPRINGS -- There was a time, so many years ago, when the black-footed ferrets inhabiting the Great Plains could have numbered as high as 5.6 million in the late 1800s.

One-hundred years later, in 1979, they became extinct, when the last surviving ferret at Patuxent Wildlife Research Center in Laurel, Md., died.

Two years later, however, a small group of ferrets were found near Meeteesee, Wyo., giving new hope to the survival of what Travis Livieri considers the flagship species of the prairies.

And he is confident ferrets will one day be taken off the federal endangered species list.

"It will be in my lifetime," Livieri said. "I firmly believe that.

He offered that observation, as well as many others as he spent the night criss-crossing a pasture in southwest Logan County, dodging prairie dog burrows and waiting as survey partner Angela Anderson hopped in and out of his pickup to stand on a single strand of electric fence, allowing the process to continue.

Livieri, executive director of the Prairie Wildlife Center in Wellington, Colo., is one of the nation's top ferret experts, called in to help out on recovery efforts. He's spent uncountable hours assisting with the species survival in the Conata Basin not far from Wall, S.D., as well as reintroduction efforts in Canada.

"This is one of the wonderful success stories of endangered species recovery," Livieri said. "Look at all the volunteers and people who come out here and help."

Anderson is a living example of that.

Although she's the outreach coordinator for the Emporia zoo, she travels to Logan County twice each year to turn her routine upside down, sleeping during the day and surveying through the night.

"I come out on my own pocket money," she said. "It's a hobby."

She's only missed one survey since the ferrets were reintroduced in December 2007.

"To me, it's part of history," Anderson said. "Being part of history. It's pretty cool."

"It's a captivating story," Livieri said of the reintroduction efforts that started in earnest after the 18 ferrets were taken into captivity in Meeteetse.

That's when an outbreak of canine distemper -- and likely, sylvatic plague -- swept through the 129 ferrets that were the last remaining vestiges of the population in the wild.

Plague, a bacteria that is carried by fleas, remains a threat to ferrets today.

That plague-free status is why Logan County's reintroduction effort has been hailed as the most important small site in the nation.

"This is one of the very few sites where plague has not been detected at all," Livieri said. "That puts another stamp of importance on this project."

But it's a threat that lurks at every corner, or in this case, every burrow.

He knows all too well what sylvatic plague -- what bubonic plague is called when it gets into wild poppulations -- can do to both prairie dogs and ferrets. Much of his time of late at the Conata Basin has been spent leading a charge to dust insecticide into prairie dog burrows to kill the fleas, as well as capture the ferrets to vaccinate them against the plague.

Over the course of two years, the 30,000 acres of prairie dogs was cut in half by the plague.

There were an estimated 223 ferrets at Conata site in 2007.

"I figure we lost a hundred, 125 of them," he said.

It was a crushing blow to a self-supporting population of ferrets.

"I'll never let my guard down," he said of thinking an area can't be hit by plague. "When it comes to the plague, I tell people it's a gigantic jigsaw puzzle. We've got the corners, but we're missing a ... of pieces in the middle."

While Logan County's project is plague-free, there's always the danger the disease could appear.

"I think we need to be vigilant," Livieri said of the danger of plague. "We need to be prepared. It may occur. It's not out of the realm of possibility it could show up on the doorstep here. I never thought it would show up in Conata Basin."

But one of the biggest fears when it comes to plague is the fear that it raises in people.

"The public just hears the word plague, and the hair on the back of our neck stands up," he said. "It's really nothing to be afraid of. You're more likely to be struck by lighting than contract plague. We have such excellent medicines today that it is not much of an issue for humans."

Yet Logan County is important not just because it's plague-free, he said.

It's also a project that's entirely on private land, he said, where the owners stood up and said they were dedicated to the idea of having ferrets and the prairie dogs they rely on for food and shelter.

"We've never quite had a private landowner outside Ted Turner's folks to do that," he said of landowners Larry and Bette Haverfield, Gordon Barnhardt and Maxine Blank, who together own about 10,000 acres south of Russell Springs. Ferrets were also reintroduced on land owned by the Nature Conservancy, which has a sharply lower prairie dog population.

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In the two weeks that Livieri, Anderson and about 45 other volunteers combed the countryside looking for the emerald-green reflection of eyes of the ferrets, nearly 45 animals were captured, vaccinated and examined.

It's unlikely, he said, that any of the captive-raised ferrets are still alive.

Ferrets, like most members of the weasel family, are territorial, ready and willing to defend that territory to the death if necessary.

Livieri said a female ferret lays claim to about 200 acres of land, while a male's territory covers nearly 400 acres.

In March and April, when breeding season rolls around, males are wanderlust in search of females.

"The females stay put," Livieri said. "They wait until the boys come to them."

In addition to helping with the survey, he will spend time getting the records of the reintroduction and subsequent surveys in order, putting them in spreadsheets and in GIS formats that will allow researchers to instantly see the results of the project.

The idea will be to develop a baseline of how many ferrets are on the ground in Logan County, rather than operating with a known minimum number of live animals -- essentially the number of animals captured in each survey.

Sightings that don't result in captures are important, he said, but they can't be confirmed.

"You're out there playing pop-goes-the-weasel with these guys," he said.

That's why animals captured are marked with dye so that searchers can document repeated sightings or those that aren't caught but spotted without the dye.

It's also fits in the broader concept of black-footed ferret recovery.

Livieri said the federal plan is currently under revision, even though it will essentially call for the same number of animals on the ground before ferrets can be considered recovered.

To move from endangered to threatened, a lower category, there needs to be 1,500 breeding adults, he said. To get the animals entirely off the list, there needs to be 3,000 breeding animals.

Today, there are somewhere between 350 and 400 breeding adults.

Livieri hailed that accomplishment, "when you consider where we've been."

Specifically, that's going from 18 animals to animals in eight states and Mexico and Canada.

There's little doubt, he said, that humans nearly doomed black-footed ferrets through the poisoning of prairie dogs and the introduction of plague.

"Saying that, I don't think we should feel guilty," he said, as that was simply part of trying to settle the west. "The sin of it is if we learned better, why don't we change our ways?

"That's the sin of it that we don't appreciate it. We've got organizations -- Save the Rain forest, on and on. There's not many people out there in the U.S. saying save the prairie."

That's why Livieri thinks mankind has a "moral obligation" to do its best to save the ferrets.

"We put ferrets in this position. We owe it to ourselves and to ferrets to give it a shot to reintroduce them. It works. We can recover this species, and that's really exciting.