Pine marten, a close relative to the fisher, is smaller and lives in the coniferous forest of Minnesota. Color of the fisher is dark brown, almost black, with a grizzled appearance caused by white bands on the guard hairs. The tail is long, hairy and bushy. One to four young are born in late March or early April. Although fisher have lived on the refuge for many years, the first documentation of fisher born on the refuge was in June 1993.
Fishers are solitary, except during mating and when rearing their young.
Fishers live mainly in the hardwood forest and are rarely observed. River Otter River otters are large weasel-like mammals, three to four times the size of a mink. Otters present a sleek appearance with their fairly small head, long slender body and long, thick tapering tail with short hair. Fur color is dark brown, a bit lighter on the underside, and often grayish or silvery on the throat. The otter's eyes are located toward the front of the face giving better frontal vision.