Tail long and slightly tapered toward the tip with musk-producing glands underneath. The short dense fur is dark brown. Chin and stomach are reddish yellow, tinged with gray.
Females are a third smaller than males.
All of the United States and Canada except the tundra and parts of the arid southwestern United States. Allied species occur in Mexico, Central and South America, as well as Eurasia. Found in streams, rivers, lakes, estuaries, and salt- and freshwater marshes. Fish, crayfish, frogs, turtles, and aquatic invertebrates, plus an occasional bird, rodent or rabbit. Feline diet with fish three times a week and vitamin E twice a week.