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Photo © by Bill Byrne Living With Wildlife Fisher in Massachusetts The fisher, Martes pennanti, is relatively common in many areas of Massachusetts, but due to its alert, secretive nature and generally solitary habits, most people have never seen this interesting predator. It was eliminated from the state by the 19TH century due to agricultural land clearing that virtually eliminated its forest habitat, but it has made an amazing comeback that began during the 1960s. Once considered strictly a wilderness species, fisher now live in more populated areas that offer mature forest habitat and the squirrels that are its chief prey. Fisher are found throughout Massachusetts except in some areas of the southeast, Cape Cod, and the islands. Description: The fisher is one of the largest members of the Mustelid or weasel family. 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 are smaller than males, weighing 4 to 6 pounds and measuring approximately 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. It has a pointed face (although not as pronounced as fox or coyote) with large, rounded ears set close to the head. It is well adapted for climbing and has sharp, retractable claws similar to those of a domestic cat. Its 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. Females typically have the darkest fur. Individuals may also have irregular white patches of fur on their chest and lower abdomen. Life history: Fishers breed from February to March and exhibit a reproductive strategy called “delayed implantation” that is common to members of the weasel family. The adult female breeds within days after giving birth, but the fertilized eggs remain dormant in her uterus for the next 10 to 11 months. Then the fertilized eggs implant in the uterine wall and begin normal devel opment. The young are born 1 to 2 months after implantation occurs. Female fishers produce 1 litter each year consisting of 1 to 4 kits, with an average litter size of 3 kits. Photo © by Bill Byrne ---PAGE BREAK--- The young are born helpless, blind, and sparsely furred. Maternal dens, typically located in a cavity high in a large tree, are used for the first 8 to 10 weeks. Once the kits become mobile, they are moved from the maternal den to one on or below the ground. It is believed that the maternal den functions to protect the helpless young from aggressive male fishers and ground predators. The female nurses the kits until they reach 4 months of age. By five months of age the kits are approximately the same size as the adult female and have begun to learn how to kill their own prey. The young remain with the female until late summer or early fall, at which time they disperse to begin their solitary lives as adults. They reach sexual maturity at one year of age, and females produce their first litter at the age of two. Habits: 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 brushpiles for resting sites. Food: Fishers are omnivorous. Their primary foods include small rodents, squirrels, rabbits, birds, eggs, fruit, porcupines, and carrion. They will also opportunistically prey on poultry and domestic cats. Although they are proficient climbers, most of their hunting takes place on the ground. As with other wildlife species, problems with fishers may sometimes arise, but these are usually restricted to predatory attacks on domestic birds, rabbits, and free ranging housecats. Most problems involving fisher can be avoided by following a few basic practices: Remove any potential food sources. Fishers are opportunistic feeders that will consistently hunt in areas where they have been successful in the past. Suspend supplemental bird feeding, as the seed attracts small mammals (particularly squirrels) which in turn attract fishers. It is also a good idea to secure trash, garbage, compost and pet food, as these are also potential attractants. Protect pets and poultry. Fishers are predators that prey on medium sized mammals and poultry. Fishers view domestic cats and rabbits as food, and will prey on them when hunting. They will also raid chicken coops and can kill numerous chickens at a time. For their safety, cats should be kept indoors at all times. Pet rabbits and poultry should be kept in secured buildings or hutches that prevent access by fishers. Educate your neighbors. If you are experiencing problems with fishers in your yard, be sure to alert neighbors so they, too, can follow these basic practices. The fisher is an important and valuable natural resource in Massachusetts. It is classified as a furbearer species, for which a regulated trapping season and management program have been established. If you are experiencing problems with fisher, or have any questions regarding this interesting predator, please contact your nearest MassWildlife District Office. Further information on fisher and other native furbearers is also available on our website: www.masswildlife.org. MassWildlife at: (413) 447-9789 (413) 323-7632 (508) 835-3607 (978) 263-4347 Southeast Wildlife District, Bourne: (508) 759-3406 or visit our website at For more information contact Western Wildlife District, Pittsfield: Connecticut Valley Wildlife Dist., Belchertown: Central Wildlife District, West Boylston: Northeast Wildlife District, Acton: www.masswildlife.org “Balancing the needs of wildlife with the needs of people.”