The fisher (Pekania pennanti) is a large, relatively secretive North American mammal belonging to the Mustelidae family, which includes weasels and otters. Though its name might suggest a diet of aquatic life, the fisher does not primarily prey on fish, making its common name a source of frequent confusion. This guide offers a detailed visual breakdown of the creature’s characteristics.
Core Physical Description
The fisher possesses a long, slender, and cylindrical body set low to the ground on relatively short, stout legs. Its overall coat color is generally a deep dark brown to black, with the legs and tail often appearing the darkest shade.
The fur is long, thick, and dense, taking on a noticeable gloss, especially during the winter months. A distinctive feature is the grizzled or frosted look that often appears around the head, neck, and shoulders. This effect is created by specialized tricolored guard hairs that have gold or silver tips.
The tail is long, bushy, and tapers to a point, accounting for approximately one-third of the fisher’s total body length.
Unique Defining Features
The head is broad and somewhat triangular, featuring a short, narrow muzzle and small, dark eyes. The ears are noticeably short and rounded, and they are set relatively low on the sides of the head.
The feet are large and plantigrade, meaning the fisher walks on the soles of its feet. Each foot has five toes equipped with sharp, curved claws that are semi-retractable. A specialized adaptation for its semi-arboreal lifestyle is the ability to rotate its hind feet nearly 180 degrees, allowing it to descend trees head-first.
The underside may feature irregular patches of white or cream-colored fur on the chest or lower abdomen. These markings are highly variable and unique to each individual. The presence, size, or shape of these patches cannot be relied upon as a universal identification marker, as some individuals may not have any visible markings.
Size and Sexual Dimorphism
Fishers display a marked degree of sexual dimorphism, which is the difference in size and form between males and females of the same species. Males are substantially larger than females, a difference that is a defining characteristic when observing the species. Adult males can weigh between 3.5 and 6.0 kilograms and measure 90 to 120 centimeters in total length.
By contrast, adult females are considerably smaller, weighing only about 2.0 to 2.5 kilograms. Their total length typically ranges from 75 to 95 centimeters. This difference means a large male fisher can weigh up to twice as much as a female, making size a very useful factor in distinguishing the sexes in the wild.