Basic Facts About Fishers

The fisher (Martes pennanti) is a member of the weasel family, similar to the marten.

© Defenders of Wildlife

Diet

Fishers eat snowshoe hares, rabbits, rodents and birds, and are one of the few specialized predators of porcupines. Fishers are effective hunters, but are also known to eat insects, nuts, and berries when prey is not available.

Population

Fishers are common in the Northeast and Midwest, but rare in the Northern Rockies and Northwest, where they are one of the rarest carnivores.

Range

The fisher is found only in North America. Historically, it ranged the northern forests of Canada and the United States as well as forests in the Appalachian, Rocky and Pacific Coast Mountains. Today, fishers are found only in parts of their historic range. In the United States, they exist in portions of the Appalachian Mountains from New England south to Tennessee; northern Wisconsin, Minnesota and Michigan’s upper peninsula; northern Idaho and western Montana; and three small West Coast populations in southwestern Oregon, northwestern California, and the southern Sierra Nevada. Reintroductions have led to their reoccupation of former habitats in Idaho, Michigan, Montana, Nova Scotia, Vermont, West Virginia, Maine, Manitoba, Minnesota, New York, Ontario and Tennessee.

Behavior

Fishers prefer large areas of dense mature coniferous or mixed forest and are solitary animals. They are mainly nocturnal, but may be active during the day. They travel many miles along ridges in search of prey, seeking shelter in hollow trees, logs, rock crevices, and dens of other animals.

Reproduction

Mating Season: April.
Gestation: Egg implantation is delayed till February or March of the next year, following which is a 30-day gestation period.
Litter Size: 1-4 kits.

The kits remain with their mother until the fall.

Threats to Fishers

Over-harvesting for pelts and loss of forest habitat due to logging and road building has significantly reduced and fragmented the fisher's range.

Climate change could increase the frequency of fires throughout the fisher’s range, removing the older, cavity-bearing trees they need for denning.

What Defenders Is Doing to Help Fishers

In both the Northern Rockies and their West Coast range, Defenders is working to secure adequate federal protections for fishers and their habitats, actively influencing policies and decisions affecting them — such as trapping in Montana, or logging on private lands in California — and preparing for changes to fisher habitat caused by climate change.