The fisher is a member of the weasel family, resembling a very large mink. It weighs as much as a red fox, but has much shorter legs. Fisher are extremely agile and active predators. Excellent tree climbers, they can outclimb marten and red squirrels. They prey upon snowshoe hare, mice, squirrels, and porcupine. Fisher will also eat insects and berries.
For more information, see http://www.dnr.state.mn.us/mammals/fisher.html