It's well after midnight on the South Dakota prairie and biologist Travis Livieri is on the hunt.
"These can be extremely elusive creatures," Livieri said. "Sometimes it's kind of like searching for a needle in a haystack."
Livieri shines a million-candlepower spotlight mounted on top of his pickup truck into the darkness, sweeping the beam of light left and right.
Then suddenly, about 100 yards away, the reflection of shiny green eyes gives away one of the most endangered animals in the world.
"Hey, we got a black-footed ferret," Livieri said.
Livieri, the executive director of a non-profit group called Prairie Wildlife Research, captures the animal, then checks its overall health, gives it a vaccination and notes it in the annual population count before releasing it back into the wild.
Prairie Wildlife Research is a non-profit group which monitors black-footed ferrets that have been released from captivity back into the wild inside recovery sites located in several Western states, including South Dakota and Colorado.
Not long ago, finding a black-footed ferret in the wild was unthinkable. Biologists thought the animal had gone completely extinct. Wanted posters offered $10,000 for a live one.
Then, in 1981, everything changed.
"A rancher's dog found one, killed it, brought it to its owner and they said, 'Oh, my gosh, they're not extinct,'" said Dr. Della Garelle, a biologist and director of conservation at the Cheyenne Mountain Zoo near Colorado Springs.
The discovery kicked off a rare second chance to bring a species back from the brink. The captive breeding program started with only 18 animals.
At Cheyenne Mountain, Garelle and Jeff Baughman are ferret matchmakers. They breed black-footed ferret "kits," or babies, in hopes of one day trading a cage for the wild open prairie.
The process begins with pairing up males and females for three days of rough ferret sex.
"Sometimes we just see motion. The box is rockin' and we don't go knockin'," Garelle said, laughing.
If everything goes right, exactly 42 days later, the kits are born.
"They are born tiny, little, helpless. They weigh only five grams. That's about five pennies," Garelle said.
Then, it's Baughman's job to turn these adorable kits into trained killers. Nearly all of a ferret's diet is prairie dog. So at about 20 days old, with eyes not even open yet, the kits get their first taste of meat.
"Once they get that taste, they are just gangbusters for meat," Garelle said. "They are strict carnivores."
In just a few weeks their new diet transforms the kits from Zhu-Zhu Pet cuteness into loud-mouthed, chattering adolescents.
"This is a bite glove," Baughman, showing off a thick, well-chewed leather glove. "Usually you don't put your fingers in the tips so if they do bite it, they're getting the glove and not your finger."
Black-footed ferrets have had an uphill climb since near-extinction. Each one alive today is the offspring of only 18 wild ferrets. That tiny genetic pool and the inevitable inbreeding has ruined their immune systems.
"They are very prone to plague, distemper, flu, pretty much any disease that walks by, they may die from," Garelle said.
The ferrets' fate is also closely tied to their natural enemy, prairie dogs. Farming, poisoning and even plague have nearly wiped them out. Many ranchers consider prairie dogs pests.
"They eat grass, cattle eat grass, and therefore it's an economic threat," Garelle said.
And as prairie dogs go, so go ferrets.
"They cannot survive without prairie dogs. Once we exterminated all those prairie dogs, that's what caused the near extinction of black-footed ferrets," Garelle said.
Then at three months old, it's moving day.
"They're going to pre-conditioning. It's very exciting," Baughman said, loading ferrets into a van.
Eleven ferret kits are shipped from the zoo to the National Black-Footed Ferret Conservation Center in Wellington, Colo., where biologist Paul Marinari runs a sort of ferret "boot camp."
"It's a big day for them. It's kind of like sending your kids off to school," Marinari said.
The ferrets will learn critical survival skills here, like how to kill and eat live prairie dogs. They'll get practice on hamsters.
"We get a lot of flack sometimes, you know, like, 'Why are you feeding them something that people may have as pets?' Well, they're carnivores," Marinari said. "Our job is to do the best job we can to take these guys off the endangered species list."
Timid ferret kits grab their mother, trying to pull her back into the safety of their metal box. Soon, however, they begin to explore -- and even dance.
"We call it the ferret happy dance," Marinari said. "Just happy to be around, not extinct."
Ferrets that make it through Marinari's boot camp get the ultimate graduation present -- a road trip to freedom.
"It's about a six-hour drive. We'll be heading up to Wyoming, then cutting across the plains into South Dakota," Marinari said, as he loads pet carriers into a white minivan.
Three hundred and thirty miles later, the animals arrive at their new home, in Badlands National Park in South Dakota. They're greeted like celebrities as bystanders and ferret enthusiasts snap dozens of photos.
"He's anxious to go and get some dinner," Marinari said, as he walks into a field holding a pet carrier with a young male black-footed ferret inside.
Once he reaches the middle of a prairie dog colony, Marinari sets the carrier down and opens the metal door.
"It's always great to get animals out of captivity. Hopefully in springtime, male meets female, and 42 days later we have a litter," Marinari said, who now works as a curator at the Smithsonian Conservation Biology Institute in Front Royal, Virginia.
Black-footed ferrets are still endangered, but today the wild population has grown from only 18 to about 1,000.
"That green eye shine just gets your heart racing a little bit," Livieri said, walking in darkness toward a black-footed ferret he just trapped.
He hopes ferrets will one day sustain themselves here on the prairie, effectively putting the captive breeding program out of business.
"Your water won't be any cleaner to drink. Your air will not be any purer to breathe if black-footed ferrets exist on this planet. So why should we save them?" Livieri said. "We were one of the causes as humans to the endangerment of ferrets. And I believe that because we were a part of it, we owe it to the species to try to recover it."