The fisher, (Martes pennanti), is one of the largest members of the Mustelid family, which includes the weasels, mink, otter, and skunk.
Fishers exhibit what is referred to as sexual dimorphism (physical differences) in body size between males and females. Adult male fishers weigh 8 to 16 pounds and measure approximately 3 feet from head to tail. Adult female fishers average 20% smaller than males, weighing 4 to 6 pounds and measuring approximately 2 1/2 feet in length. In both males and females, the tail accounts for approximately 1/3 of the total body length.
The fisher exhibits the typical "weasel" shape with a long, slender body, short legs, and furred tail. They have a pointed face (although not as pronounced as fox or coyote) with large, rounded ears set close to the head.
They are well adapted for climbing and have sharp, retractable claws similar to those of domestic cats. Their coloration is generally a rich brown to black with grizzled grayish coloring on the head and shoulders and the darkest coloring occurring on the rump, tail, and legs. Individuals may also have irregular white patches of fur on their chest and lower abdomen.
Although very secretive and rarely seen, the fisher is found throughout Massachusetts. It's range has expanded to areas in the southeast and most recently, Cape Cod. Fishers are not on the islands of Nantucket and Martha's Vineyard. Though it is not unusual to see this animal in suburbs, the fisher prefers wooded habitat. During the early 1800's fishers were extirpated from Massachusetts due to agricultural land clearing that virtually eliminated their forest habitat.
Fishers are shy and elusive animals that are rarely seen even in areas where they are abundant. They can be active day or night and tend to exhibit crepuscular (dawn and dusk) and nocturnal activity in the summer and diurnal (daytime) activity in the winter. They remain active year round and do not hibernate. Their preferred habitat is mixed forest with heavy canopy cover as they tend to avoid traveling in large open areas. They commonly use hollow logs, stonewalls, tree cavities, and brush piles as resting sites.