Fisher

What is a fisher and where does it live in North America?

The fisher (Pekania pennanti) is a North American carnivore belonging to the weasel family (Mustelidae). It is characterized by a weasel-like body, a bushy tail, a tapered muzzle, and small, rounded ears. Adults typically weigh between 1.4 and 6.8 kg (3–15 pounds).¹²

In North America, fishers inhabit coniferous, deciduous, and mixed forests across Canada, the American Upper Midwest, the Northeast, and selected areas of the American West. While they were once heavily trapped for their valuable brownish-black fur, they are currently considered a species of least concern, though they remain vulnerable to habitat loss and fragmentation.¹

How does the fisher’s physical appearance and size compare to other members of the weasel family?

The fisher (Pekania pennanti) is a member of the weasel family (Mustelidae) that shares the characteristic elongated, tubular body shape common to many mustelids. However, it is notably larger than many of its close relatives, such as the mink and pine marten.³¹⁴⁵

Physical Comparison

• Size: Adult fishers typically measure 50–63 cm (20–25 inches) in length, excluding their 33–42 cm (13–16.5-inch) tail, and weigh between 1.4 and 6.8 kg (3–15 pounds). In contrast, smaller mustelids like the least weasel weigh as little as 25 grams (0.9 ounce), while even the long-tailed weasel typically weighs only 85–350 grams.¹³⁴
• Appearance: Like other mustelids, the fisher possesses a tapered muzzle, short limbs, and five digits on each foot equipped with sharp claws. While many weasels have short, dense fur that may turn white in winter, the fisher is known for its thick, brownish-black coat.³¹⁴
• Sexual Dimorphism: Similar to many other members of the weasel family, male fishers are significantly larger and heavier than females.¹⁴

What are the fisher’s hunting and feeding habits?

The fisher (Pekania pennanti) is a versatile predator that hunts both on the ground and in trees. Despite its name, the fisher does not actively catch or eat live fish, though it may consume dead fish if it happens upon them.¹⁷

Its hunting and feeding habits include:

• Dietary Range: The fisher is a carnivore that preys on a variety of animals, including various rodents. Notably, it is one of the few predators capable of successfully hunting porcupines.¹
• Omnivorous Tendencies: In addition to its carnivorous diet, the fisher also consumes fruits and sometimes nuts.¹
• Foraging Behavior: As a reclusive member of the weasel family, it navigates dense woodland environments to secure its food, utilizing its agility to hunt across different forest strata.¹⁷

What is the fisher’s scientific name and how is it classified taxonomically?

The fisher is scientifically known as Pekania pennanti.¹

Taxonomically, it is classified within the following hierarchy:

• Kingdom: Animalia
• Class: Mammalia
• Order: Carnivora
• Family: Mustelidae
• Genus: Pekania¹

While the species was traditionally grouped with martens and sables in the genus Martes, 21st-century genetic research demonstrated that it is distinct from those animals. Consequently, the fisher was reassigned to its own unique genus, Pekania.¹