Wisconsin’s 284 river otter records trace the state’s water. The strongest county showings, Vilas, Burnett, and Oneida, fall across the lake-dense north, while Crex Meadows, Fish Lake, and Horicon wildlife areas anchor the record in the marshy lowlands and the Saint Croix National Scenic Riverway carries it down the western border.
A swimmer built for cold water
An otter is a streamlined member of the weasel family with dense underfur, a muscular tail, and ears and nostrils that close underwater, built to hunt fish, crayfish, and frogs below the surface. It needs two things Wisconsin has in abundance: connected open water and undisturbed banks for denning, often in commandeered beaver lodges or muskrat burrows. Between hunts it travels widely, and its slides down muddy banks and fresh snow are the sign most people find first.
No off season
Otters stay active through a Wisconsin winter, fishing beneath the ice and moving between breathing holes, which keeps records coming in every month of the year. Counts rise in May, when families with young kits grow conspicuous along shorelines, and again in August and September as juveniles begin traveling on their own and open water fills with boaters and anglers who are there to see them.
Status in Wisconsin
NatureServe ranks the North American river otter S4, Apparently Secure, in Wisconsin, and the species is native to the state. USGS NAS does not list it as nonindigenous here.
