DEEP: Fisher Fact Sheet

Fisher Fact Sheet

FISHER
Martes pennanti

{Fisher Illustration}
Copyright 1997

Habitat: Large tracts of coniferous or mixed hardwood-softwood forests containing large trees for denning.
Weight: Males: 8 to14 pounds; females: 4 to 6 pounds.
Length: Males: 36 to 40 inches; females: 30 to 36 inches.
Diet: Squirrels, rabbits, mice, voles, carrion, fruits, mast (primarily beechnuts), porcupines, birds, and frogs.

Identification: The fisher’s long, slender body, short legs and elongated, bushy tail are usually dark brown to nearly black. The tail, rump and feet are darkest, in contrast to the head and shoulders, which are lighter in color and often grizzled in appearance, especially in males. Some individuals have a white chest patch. Fishers have five toes on each foot and semi-retractable claws which contribute to their ability to climb trees.

Range: Southeastern Alaska to Hudson Bay, through Canada, south into the northern United States. Also, in the Rocky Mountains in Wyoming and the Sierra Nevada in California.

Reproduction: In Connecticut, fishers have their young in March and April. The two to four kits are born with closed eyes and are helpless. The few accounts of natal dens indicate that tree cavities are used for birth and the early rearing of young. Only the female cares for the young. The kits develop rapidly and are weaned in four months. Both males and females are sexually mature at one year of age, but females will not bear offspring until age two.

History in Connecticut: In the 19th century, fishers became scarce due to forest logging, clearing for agriculture, and overexploitation; by the 1900s, fishers were considered extirpated from the state. Reforestation and changes in land-use practices have restored the suitability of the fisher’s habitat in part of its historic range, allowing a population to begin recolonizing the northeastern section of the state. Fishers did not recolonize suitable habitat in northwestern Connecticut because the region was isolated from a source population. Fishers were rare in western Massachusetts and the developed and agricultural habitats of the Connecticut River Valley were a barrier to westward expansion by fishers in northeastern Connecticut. A project to reintroduce this native mammal into northwestern Connecticut was initiated by the DEP Wildlife Division in 1988. Fishers were obtained by first trapping wild turkeys in Connecticut for release in Maine. Funds from reimbursement for the turkeys were used to purchase fishers caught by cooperating trappers in New Hampshire and Vermont. In what is termed a "soft release," fishers were penned and fed at the release site for a couple of weeks prior to being released. Through radio-tracking and snow-tracking biologists found that the fishers remained in northwestern Connecticut, had high survival rates, and successfully reproduced. As a result of this project, a viable, self-sustaining population of this native mammal is now established in western Connecticut. Fishers are found throughout eastern Connecticut as a result of natural range expansion.

In 2005, Connecticut instituted its first modern day regulated trapping season for fishers. Most northern states have regulated fisher trapping seasons. Fisher fur is valuable, especially the smoother, more silky pelts of the females.

Interesting Facts: The fisher is a large member of the Mustelidae (weasel) family. Its name is inappropriate because, unlike the closely related river otter, fishers seldom eat fish. The name may have been derived from “fitch,” the European polecat, a species familiar to early settlers who may have seen a resemblance or mistaken the fisher for the polecat. In French, the pelt of a polecat is called “fiche,” “ficheux,” or “fichet,” names which are similar to “fisher.” Common names include fisher cat, black cat, and pekan.

The fisher has a high metabolism typical of most members of the weasel family. Although primarily nocturnal, it is active day and night throughout the year and solitary, except for a brief period during the breeding season. All mustelids, including fishers, undergo delayed implantation; the fertilized ovum develops only slightly and then remains dormant for nine to 10 months before attaching to the uterine wall and completing growth. About one week after a female gives birth, she breeds again.

Because fishers seldom travel in open areas and tend to be nocturnal, they are rarely seen by humans. They have not been studied as extensively as many other wildlife species because they are difficult to observe. Home range estimates vary, ranging from three to 15 square miles and averaging four to eight square miles in suitable habitat. Males range over larger areas than females. Population density also varies with habitat suitability; there may be an average of one fisher per three to five square miles in quality habitats.

Fishers also use tree cavities as non-natal dens and will den or rest in the thick growth of conifer trees and in tree nests of squirrels or large birds. They are known to use ground cavities, such as rock crevices, in winter.
Fishers hunt by zig-zagging through areas of thick, regenerating forest vegetation, but they traverse areas with little ground cover in a relatively straight line, hardly changing direction. Capable climbers, fishers often investigate large trees that might harbor prey, such as squirrels, that den or nest in trees. They do not stalk or chase prey but rely on surprising their quarry.

Alert and secretive, the fisher is a rewarding sight to the wildlife observer. Finding and identifying fisher tracks can add interest to a winter hike or cross-country ski trip.

{Logo} The Technical Assistance Informational Series is 75 percent funded by Federal Aid to Wildlife Restoration - Pittman-Robertson (P-R) Program. The P-R Program provides funding through an excise tax on the sale of sporting firearms, ammunition, and archery equipment. The remaining 25 percent of the funding is matched by the Connecticut Wildlife Division. (rev. 10/05)