Article for November - December 2009
For Wildlife Watchers: Mink
by Rob Simbeck
photography by Phillip Jones
Mink are members of the weasel family, along with otters, martens, fishers, wolverines and badgers, and are generally found in and around water.
Mink fur is great at keeping people warm because it's so good at keeping mink warm. In part, at least, we can thank cold water. Water drains heat from the body twenty-five times faster than air, and an animal that spends time in water summer and winter had better be insulated. Fur is the mink's first line of defense, with a dense, soft underfur that insulates and repels water and a longer outer layer of guard hairs. The combination has made mink desirable as winter clothing for millennia.
Mink are members of the weasel family, along with otters, martens, fishers, wolverines and badgers, and are generally found in and around water. Their slightly webbed feet and sleek bodies make them excellent swimmers and divers, although they are terrific climbers as well. Males are about two feet long, not including a five- to nine-inch tail, with females just a little smaller. They weigh from one to three pounds in the wild, with farm-raised mink reaching up to seven pounds.
Mink - Mustela vison
Description: Males up to two feet long with a five- to nine-inch tail. Females smaller. Sleek, with brown fur with white markings on throat, chest, belly. Up to three pounds.
Range and Habitat: Streams, lakes, ponds, marshes, with brushy or rocky cover nearby. Throughout Canada and much of U.S. except desert Southwest. Relatively abundant in Piedmont and south coastal marsh areas. Sparser elsewhere, with reintroductions along coast above Charleston.
Reproduction: Mates in late winter. Young born by April. Generally stay with mother until their first fall.
Viewing Tips: Waterways along southern coast and increasingly on northern coast, in the piedmont and some river systems. Active during evening and at daybreak.
That highly prized fur is generally dark brown, with white markings on the throat, chest and belly, and darker fur at the end of the tail. Adding to the mink's warmth is subcutaneous fat, which can be processed into mink oil, used to condition and preserve leather and in the manufacture of hypo-allergenic facial oils and cosmetics. Mink also produce, from two anal glands, a secretion with a strong skunk-like odor, which is used as a defense mechanism and as a territorial marker—and these are very territorial animals. A male will not tolerate another male in its territory, although it will be less aggressive toward females with overlapping territories. The mink spends much of its time in a core area with a good food supply, traveling along the banks of a creek or river or the edge of a lake or marsh, visiting the edges of its territory now and then to mark with scent or scat and defend against intruders. Mink will dig burrows in stream banks, but they prefer the dens of other mammals, often lining the interior with leaves and grass, and sometimes the fur of rabbits or other animals they’ve eaten.
Males and females come together for mating in late winter or early spring. Mating is often violent and can result in bites and scars on the female. Ovulation is induced from about one to three days after mating, and since females are receptive about every seven days during the three-week breeding season, additional mating can result in more than one male fathering a litter of kits. Gestation lasts thirty days, but delayed implantation can make the process last forty to seventy-five days. The female produces one litter, usually three to four young, a year, with a nursery perhaps under tree roots, in a hollow stump or in a brush pile near water. The young are born pink and wrinkled, weighing a quarter of an ounce. They open their eyes at three-and-a-half weeks and are weaned at eight or nine weeks. Extremely playful, they learn to hunt from their mother and will stay with her until late summer or early fall. Females are sexually mature at a year old.
South Carolina's mink population, once abundant, declined dramatically about half a century ago, with various forms of pollution thought to be at least one cause, since mink are highly susceptible to environmental contaminants. A recent paper by Buddy Baker and Jay Butfiloski, former and current manager, respectively, of the S.C Department of Natural Resources' Furbearer Project, cited widespread reports from trappers in the 1980s and '90s that mink were "rare or absent from areas of former abundance even though the habitat is seemingly intact."
Since 1999, a DNR restocking effort has aimed at restoring the mink population along the coast north of Charleston, where mink have essentially been absent for decades. The stocked minks were moved from coastal areas south of Charleston, where their populations have remained strong, after an initial attempt to relocate them from Louisiana.
"They're fairly high strung and don't like to be constrained for long periods of time," says Butfiloski, "and we realized to make it work we were going to have to catch them in South Carolina." Every attempt is made to have them transferred within twelve hours, he adds.
The program has restocked 220 mink, with enough success that the area first restocked—in the vicinity of Cape Romain National Wildlife Refuge near McClellanville—has now become the source of mink for other restocking efforts in the Little River and Hog Inlet areas.
"These are the first we’ve caught north of Charleston and moved," Butfiloski says. "It works out really well because we don’t have that long haul—bringing them all the way up the state from the marshes around Hilton Head or Edisto."
Mink numbers remain stable along the southern coast and through the Piedmont region, although trapping in the state remains well off historic highs. Since 1990, the average annual number of mink taken statewide by trappers is under twenty.
Mink are active mainly at night, especially near dusk and dawn, and spend most of their time feeding. They have excellent vision, hearing and smell and are aggressive predators, supplementing a diet of fish with crayfish, salamanders, frogs, crabs, rabbits, squirrels, muskrats, young birds, mice, ducks and chipmunks.
Mink are fearless in defending themselves from predators that include bobcats, foxes, coyotes, great horned owls, dogs and alligators, none of which are serious threats to their population. Many are hit by cars, but development and wetland destruction are the prime threats, as they are for many other species.
Still, the signs are positive at the moment, given the efforts of the Furbearer Project to bring them back in areas that haven't seen them for a while. It's a scenario that is thrilling quite a few wildlife watchers. One is Henry Lemon, a Charleston pediatrician and avid outdoorsman, who dropped an e-mail to DNR Marine Resources Division Deputy Director Robert Boyles about a recent encounter.
"I saw a mink (my first sighting ever) last evening around sunset along a stretch of marshy shell bank along the Intracoastal Waterway between Dewees and Capers Inlet," he wrote. "I've fished for over twenty years in Charleston and thought I'd seen it all—but that brief glimpse of a mink was one to remember. If you know the folks who've been restocking them, tell them 'Thank you!' "
Dr. Lemon, you just did.
Rob Simbeck is an award-winning free-lance writer living in Nashville, Tennessee.
© 2009 South Carolina Wildlife Magazine, November - December 2009 - www.scwildlife.com