Northern Rockies Fisher

Northern Rockies Fisher, USFWS Photo

(Pekania pennanti)

Physical Characteristics: 31 – 40 inches long and 3 – 13 lbs. predator with fox-like face, rounded ears and pointed snout. Resembles dark, overgrown squirrel. Males are roughly 20% larger than females. Member of weasel family.

Diet: Solitary, opportunistic hunter which preys on squirrels, hares, mice, muskrats, grouse, and birds. Eats porcupine by repeatedly attacking head or rolling animal on its back and piercing unarmed underside. Supplement diet with insects, nuts, berries, and mushrooms; not averse to eating carrion. Despite name not known to eat fish.

Habitat: Prefers old-growth, dense, coniferous forest. Usually not found in young forests (early succession) or where logging has occured. Hollow trees/logs, brush piles, rock crevices, and cavities beneath boulders serve as den sites. In winter den may be excavated from snow.

Range: Only found in North America; common in Northeast and Midwest, but one of rarest carnivores in Northern Rockies and Northwest. Fishers in Clearwater Basin are thought to be healthiest population in West. These populations are genetically unique because descended from Fishers that originally inhabited area – other fishers were reintroduced to North Central Idaho from British Columbia in 1960s.

Reproduction: Reproductive cycle lasts almost entire year; give birth to 3 – 4 kits in spring. Nurse kits in den for roughly seven weeks. At three months begin to hunt with mother; by fall are independent. Females enter estrus shortly after giving birth and leave den to find a mate. Implantation delayed until following spring; cycle is renewed.

Threats: Logging (old-growth) and aggressive trapping resulted in decline/extirpation throughout West. Increase in fire frequency and intensity threatens populations too. Best available science suggest less than 500 animals in entire Northern Rockies.

Miscellaneous: Particularly nimble in trees; anatomy of ankles allows feet to rotate sufficiently which allows to descend trees headfirst. Ability to hunt porcupine makes them of value to timber companies; Fishers can reduce tree damage caused by porcupines.

Learn more about efforts to recover Northern Rockies Fisher.

 

 

 

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