Critter Corner No. 2 – The Mink by George Sly

You may recall that, in our first edition of Critter Corner, we dealt with one of the Goose Pond wetland’s most characteristic mammals – the muskrat. It seems appropriate then to follow up with a mammal whose life is closely linked with that of the muskrat. The mink is a member of the weasel family Mustelidae. An adult male weighs about two pounds and is about two feet in total length. Other mustelids in Indiana include the river otter, long-tailed weasel, least weasel, and badger. The striped skunk was once placed in the weasel family but biologists have now shifted the skunks into their own taxonomic family. In recent years, taxonomists have also debated whether or not the American weasels should be placed into their own genus (Neovison). In many books, Whitaker’s Mammals of Indiana: A Field Guide for example, they are still placed in the genus Mustela. This genus name come from the Latin word for weasel.

Like the muskrat, the mink is highly dependent upon the presence of water. This makes the marsh and riparian (streamside) habitats of Goose Pond FWA ideal haunts for mink. Mink are able swimmers and can dive to several feet below the surface. Although they are primarily nocturnal, mink do occasionally move about and hunt during the day. Thus, it is not totally unexpected to see one nosing along the edge of the water or crossing one of the roads that pass through the property. Not only do mink prey upon muskrats, they will also use the lodges and burrows constructed by these rodents as dens. The closeness of the mink-muskrat relationship is revealed by the fact that a normally muskrat specific mite species was found on 42% of the mink specimens examined by Indiana State University mammalogist John O. Whitaker.

Mink are carnivorous but opportunistic so the animals upon which they prey are varied. D.M. Brooks, who studied mink at Jasper-Pulaski FWA many years ago, reported that their method of eating muskrats was distinctive. He reported that the muskrat’s upper body was opened whereupon the mink ate the muskrat’s heart, lungs, and liver. The mink then fed on the muscles and bones of the forelegs and then the hindquarters. The head, feet, tail, and skin are left uneaten. Aside from the muskrat, mink have also been recorded as eating other mammals including rabbits, voles, shrews, and moles. Other prey known to be taken, at least occasionally, are birds (such as coots), catfish, snakes, frogs, snails, and crayfish. Mink were, in times past, often culprits in attacks on poultry. Of course, with the demise of the family farm, this problem is insignificant now.

Mink are thought to mate mostly in the month of March. Like other mustelids, females exhibit delayed implantation. After fertilization, embryonic growth begins but then enters a period of diapause (dormancy) during which development stops for a time. Once implantation occurs differentiation of the embryo continues and most young are born in April or May. Litter size is usually three to six. Mink babies are altricial and three or four weeks pass before they are active and eat solid food. The young remain in the nest for as long as two months before they began to follow their mother and learn to hunt.

Like other wild animals, mink have their adversaries. Whitaker (1982) has found a variety of internal parasites in the specimens he examined. These included internal parasites in the form of flukes, roundworms, and tapeworms. External parasites were common and included fleas, lice, mites, and ticks. Mink seem to have few predators but wild canids such as foxes and coyotes may attack them. Great horned owls, also a predator of striped skunks, likewise attack mink. The mink is a species that has long attracted the attention of fur trappers. Some trapping of mink is still done at Goose Pond FWA. Property Manager Brad Feaster reported that 52 animals were taken last year. Fur prices for mink are about $22.00; this represents revenue of over eleven hundred dollars for the trappers involved. Of course the greatest long term danger to mink is the draining of wetlands.
So, on your next trip to Goose Pond FWA, be alert. While cruising one of the area’s back roads or quietly watching a stalking great-blue heron you just might, if luck be with you, spot one of the property’s most elusive residents.

Resources:
Brooks, David M. 1959. Fur Animals of Indiana.
Pittman-Robertson Bull. No. 4. Indiana Dept. of Conservation

Mumford, Russell E. and J.O. Whitaker, Jr. 1982. Mammals of Indiana.
Indiana University Press. Bloomington.

Whitaker, J.O., Jr. 2010. Mammals of Indiana: A Field Guide.
Indiana University Press. Bloomington.