The discovery of black-footed ferrets where none were known to exist has encouraged but not surprised federal officials on a mission to bring the endangered species back from the edge of extinction.
An adult and two juvenile ferrets were discovered last week on the Standing Rock Sioux Reservation in South Dakota. A Nebraska environmental consulting company spotted and photographed the critters during a nocturnal spotlight survey of a prairie dog town.
The masked mammals were found about 70 miles north of the nearest colony of reintroduced ferrets on the Cheyenne River Sioux Reservation.
Initial speculation by the tribe and the spotters was that the Standing Rock ferrets were a long-lost colony, but that's unlikely, said Pete Gober, coordinator of the U.S. Fish and Wildlife Service's national ferret recovery program.
“It would be remarkable if they were an undiscovered population because we've chased a lot of leads for decades and we haven't found one since 1981,'' he said. “It's not impossible that these moved up from Cheyenne River.''
The three ferrets were spotted by Michael Gutzmer and Thomas Murphy during night surveys Oct. 31 and Nov. 1. Gutzmer is project manager of New Century Environmental of Columbus, Neb. Murphy is a biological technician.
Gutzmer and Murphy were slowly driving across a prairie dog town under a clear sky and full moon in a Chevrolet Silverado pickup truck. They scanned a 180-degree sweep of the prairie illuminated with high-beam headlights and two panning spotlights mounted on the vehicle.
Prairie dog towns are alive with activity by predators at night. Ferrets prey on sleeping prairie dogs.
About 12:45 a.m. Oct. 31, Gutzmer spotted two emerald-green dots of eyeshine — the tell-tale sign of a black-footed ferret — illuminated by a spotlight.
The animal's distinctive long, slender body, thick fur mass and long tail were additional giveaways.
The next night, Gutzmer and Murphy spotted two smaller ferrets, presumed to be juveniles, in two different locations in the same prairie dog town. They caught a 10-second look at another Monday night.
Gutzmer snapped pictures of the ferrets found the first two nights with a camera equipped with a 250 mm telephoto lens. He said he was about 35 feet from the adult and 10 feet from the juveniles.
“It takes a lot of patience,'' Gutzmer said. “They're very curious creatures. They stayed near their holes. Sometimes their heads would pop up.''
Since the initial sighting, Gutzmer set out four motion-sensitive trail cameras in an attempt to capture more ferret photos.
The Standing Rock Reservation spans 1 million acres in north-central South Dakota and spills into North Dakota. Gutzmer said there are least 200 prairie dog towns of at least 80 acres each on the reservation. Most have not been surveyed for ferrets and other wildlife, he said.
“I still think there's large potential to find an isolated colony of ferrets,'' Gutzmer said.
The only way to tell if the Standing Rock ferrets are a previously unknown colony or migrants from a reintroduced group is by genetic testing. Ferrets would be trapped for blood tests and released.
Gober, the federal recovery coordinator, said ferrets have been known to easily travel tens of miles over relatively short periods of time.
“They'll hop, skip and jump from prairie dog town to prairie dog town,'' he said.
Whether the Standing Rock ferrets are migrants or a lost colony, Gutzmer said finding them is important to the preservation of the species.
“Just to document them is extremely rare,'' he said, “considering there are less than 1,000 in the wild.''
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» Black-footed ferrets are 2-foot-long, weasel-like predators with a yellowish buff body, black feet and a black mask. They weigh up to 2½ pounds. They are solitary and nocturnal.
» Black-footed ferrets are among America's rarest animals and have been on the endangered species list since 1967. They depend almost exclusively on prairie dogs for food and their burrows for shelter.
» Presumed extinct in 1979 when the last individuals from a South Dakota population died in captivity without successfully breeding.
» Two years later, a colony of 130 was discovered near Meeteetse, Wyo. Disease wiped out the wild population a few years later, but not before biologists had taken 18 into captivity. » Those ferrets formed a captive-breeding population that has produced more than 6,000 young. Omaha's Henry Doorly Zoo was one of the original breeding sites.
» About 200 ferrets are sent into the wild annually. Three thousand have been released over the last two decades. There are an estimated 500 to 1,000 ferrets in the wild.
» No ferrets have been reintroduced in Nebraska, where prairie dogs are public enemy No. 1 on many farms and ranches.
Source: U.S. Fish and Wildlife Service, World-Herald files