Family: Mustelidae, Weasels view all from this family
Description Long body; looks stockier than most other mustelids because of its long fur. Dark brown above and below. Broad head has grayish cast; pointed snout; small ears. Bushy tail. Male larger than female. L 31–41" (790–1,033 mm); T 11 3/4–16 5/8" (300–422 mm); HF 3 1/2–5 5/8" (89–143 mm); Wt 3–18 lb (1.4–8.2 kg).
Similar Species American Marten is smaller, with orange throat patch. Mink is much smaller, with white spotting on chin.
Breeding Mates March–April; implantation delayed 10–11 months; 1–6 young born the following spring; total gestation nearly 1 year. Young born blind, usually in a nest in a large, hollow tree; weaned at 3–4 months.
Habitat Mature, dense, coniferous or mixed coniferous-hardwood forest with closed canopy.
Range Southern tier of Canadian provinces south to n California and Rocky Mountains to Utah; in East, to New York and New England.
Discussion A solitary animal of dense forests, the Fisher is primarily nocturnal like most mustelids, but is sometimes abroad by day. A good climber and swimmer, it travels a home range of 50 to 150 square miles (130–400 sq km), wandering even farther in winter when food is scarce. It moves about the home range a great deal (the male more than the female), following well-established trails, running along fallen logs, moving among branches from tree to tree, and taking refuge in temporary dens in crevices, underbrush, or holes dug in snow. The Fisher also uses a maternity den, located in a hollow tree. Snowshoe Hares and Common Porcupines are the Fisher’s main prey. Porcupines are well armed, and occasionally a Fisher is injured or even killed by the quills. The Fisher begins with repeated attacks at its victim’s face; the porcupine rotates to keep its back to the circling Fisher, sometimes putting its face against a tree or other object for protection. The Fisher may climb the tree, then come down headfirst to force the porcupine away from the tree. The Fisher makes the kill when the porcupine has been weakened by facial wounds. It feeds on the internal organs first, consuming the entire animal over two or three days. Although an individual Fisher does not kill a large number of porcupines, this prey is very important because it supplies so much food, providing the Fisher with energy from stored fat for a month. The Snowshoe Hare is the Fisher’s usual victim, but squirrels, mice, and chipmunks also fall prey to this animal, usually by a bite to the back of the neck. Carrion, fruit, and other plant material round out its diet. The Fisher’s common name is a misnomer and its origin is unknown, for this animal seldom feeds on fish; the name was probably due to confusion with the Mink, an avid fisher. Female Fishers first mate at one year. Copulation lasts about an hour. The male apparently does not participate in raising the young. If disturbed, the Fisher hunches its back like a cat and may hiss, growl, snarl, or spit. Because of its reputation as a valuable fur-bearer, with female skins especially prized, and the ease with which it can be trapped, the Fisher has been extirpated in many areas. Loss of habitat has also depleted populations, as this animal requires extensive wilderness.
