By Darci Palmquist
No black-footed ferrets — once believed extinct — have been born in the wild in Kansas for 50 years.
This endangered mammal — the only ferret native to North America — is making a comeback on The Nature Conservancy’s Smoky Valley Ranch and other private lands in Logan County, Kansas.
Ecologists working there discovered four litters of ferret kits in August, just nine months after the scientists reintroduced two dozen adults into the wild. Nature.org spoke with Rob Manes, director of conservation science for the Conservancy in Kansas, about what these births mean for the black-footed ferret's prospects for survival.
Nature.org: Congratulations! You must be very excited about these wild-born ferrets — the first documented births in 50 years.
Rob Manes: I'm very encouraged and pleased that the introduced ferrets have survived the winter and there are new births. Wild-born ferrets are generally better able to survive in a natural setting — they seem to have better instincts for feeding and avoiding predators — than captive-reared animals.
In my lifetime there have been no ferrets in Kansas. So yes, I’m very encouraged.
Nature.org: Tell us about surveying for ferrets — how did you find the new litters?
Rob Manes: Ferrets are solely nocturnal, so we start searching at night when they're out hunting prairie dogs for dinner. Sleep deprivation is always part of the deal.
But despite working in the dark, ferrets are actually fairly easy to spot.
Searchers spent four nights in August using spotlights mounted on the top of our vehicles. There were a few dozen people working different shifts: Conservancy staff, many USFWS staff, and a number of volunteers.
Every animal has a different "eyeshine" — the reflection of light off their eyes. Black-footed ferrets’ eyes reflect emerald green when spotlighted. And they're very curious. When you shine a spotlight on them, they often look right into it. Then they turn, run, turn again, and look.
Nature.org: What do you do after you spot a ferret?
Rob Manes: We watch to try and determine which prairie dog hole it goes into. Then everyone bails out of the truck fast, running over and marking the hole with a reflector [like used in driveways].
We plug nearby burrow openings — those close enough to be escape routes — with short segments of fence post and set a wire box trap at the opening where the ferret disappeared. It leaves the ferret no choice but to run into the trap.
Once we've caught them, we give them a health check-up, fit them with a transmitter if they don't have one already, dust for fleas and vaccinate for distemper.
We caught one juvenile [see pictures] and spotted three other family units.
Nature.org: What do these four confirmed litters mean for black-footed ferrets — are they in the clear now?
Rob Manes: Black-footed ferrets were thought to be extinct until a small population was found in Wyoming in 1981. But that population was seriously threatened by disease, so they were captured and brought into captivity — scientists feared they would otherwise all die out.
Since then, ferrets have been bred in captivity and reintroduced where large prairie dog colonies provide suitable habitat. There are nine major reintroduction sites in the United States. One of the reasons Smoky Valley Ranch and nearby lands are so important is because they have stayed free from sylvatic plague for a long time.
There may be more in the wild now, in northwest Kansas alone, than there were in all of North America when the Wyoming ferrets were discovered. So there's hope.
Nature.org: What happens next, now that you know the introduced ferrets are successfully reproducing?
Rob Manes: Later this fall we’ll reintroduce more ferrets — maybe about eight. It depends on how many are available at the breeding facility.
Other than that, we continue maintaining the prairie dog population.
Ferrets rely on prairie dogs for survival. They eat prairie dogs almost exclusively and use their burrows. But we don’t want an unlimited number of prairie dogs on Smoky Valley Ranch, because they’ll spread to nearby ranches — and most ranchers don’t want them competing with livestock for forage.
So, it’s important to limit prairie dog expansion in order for the reintroduction to be accepted in the local community.
Nature.org: Why should people care about ferrets?
Rob Manes: As with any species, you never know its direct value to humanity. For instance, some tree frogs in South America are believed to be keys to treating certain cancers. You never know what values are lost to humans when a species disappears.
Ferrets are very unique species and integral to the shortgrass prairie habitat. They are predators and they're preyed upon by animals like the great horned owl. Each species is, in some way, connected to many others. If the ferret disappears again, other species will surely be affected.February 18, 2011
Darci Palmquist is editorial manager for nature.org.