The fisher (Martes pennanti) is the second largest member of the weasel family found in Massachusetts; only the river otter is larger. Although many people call them “fisher cats,” the name is inappropriate. They are neither members of the feline family, nor do they catch fish.
Fishers were extirpated from much of the northeast in the 1700 and 1800s when loggers and farmers cleared the forests and unregulated trapping took its toll. In the east they are now found in southern Canada, New England and New York, and in scattered locations in Pennsylvania, West Virginia and Virginia.
In the 1950s logging companies, with permission from each state, reintroduced fishers into northern New England to control porcupines. At the time, porcupines were decimating seedlings planted by the timber companies to reestablish trees in logged areas. Fisher is the only species to deliberately target porcupines as prey.
During the late 1800s, as farms were abandoned and the land became reforested, fisher numbers rebounded. With the exception of Cape Cod and the Islands, they may be potentially found in practically every community in Massachusetts.
As with other members of the weasel family, fishers have a long, low profile when moving along the ground. They average 32 to 40 inches in length, including a tapering, 12 to 16-inch tail. The males are considerably larger than the females. The legs of a fisher are short and stout and their feet possess retractable claws, which they use for climbing. A fisher’s coat is dark brown, dense, and glossy.
Except during their brief mating season, fishers are solitary creatures and are active both night and day throughout the year. Research undertaken by University of Massachusetts graduate student, Eric York, shows that the home range – the undefended area used for foraging, mating, and raising young – of a female fisher in Massachusetts is 3 to 5 square miles and 4 to 8 square miles for a male.
For the most part fishers are carnivores, although they will eat berries and fruit when they are available. They eat rabbits, snowshoe hares, squirrels, raccoons, mice, reptiles and amphibians, insects, carrion and, occasionally even house cats. Even though fishers do not catch live fish they will eat dead fish found on the shore of a lake or pond.
Fishers are one of the few mammals that prey on porcupines. Porcupines are difficult to kill, but a dead porcupine can provide many days of food for a fisher, so it is worth the effort. While on the ground, not in trees, the fisher continually attacks the only vulnerable portions of the porcupine’s body, its face and underbelly. When facial wounds have weakened the porcupine, the fisher goes in for the kill. Again, to avoid the quills, the fisher eats its prey starting at the head, neck, or underbelly.
Fishers do not hibernate and they rarely occupy dens for long periods of time. Their temporary dens, which are used for resting and for shelter during winter storms, are located in rock crevices, hollow logs, tree cavities or vacant porcupine dens. Females usually establish their natal dens in tree cavities.
Breeding takes place in March or April when females are one to two years old. After a delayed implantation period of 10 or 11 months, the blastocyst (the earliest stage of the embryo) is implanted in the womb, possibly stimulated by changing day length. Once implanted in the womb the embryo develops in only six weeks. Young fishers are born the following March or early April, and females are able to mate again within just a few days after giving birth.
A litter of 1 to 4 kits is born in a maternity den in a hollow tree. The blind and helpless newborns are dependant on the mother for nearly four months (the male does not help rear the young). Young fishers begin to capture their own prey at four months of age, and disperse by the time they are five months old. By radio collaring the young, researcher Eric York has determined that after the young disperse, they can travel up to 70 miles in search of their own territory.
SITUATIONS AND SOLUTIONS
Until recently, the Mass Audubon rarely received reports of fishers, but sightings have increased significantly since 2000, especially in eastern Massachusetts.
There may be a number of contributing factors, but surely one impact is the reforestation of land previously cleared for farming, particularly in central Massachusetts.
Also, biologists have traditionally assumed that fishers could only survive in large, contiguous forests of mixed conifers and hardwoods. In recent years however, fishers have begun to occupy second-growth forests (land cleared for farming and now reverting back to forests) and sightings are becoming increasingly more common in locations near human dwellings. This increase suggests that the habitat requirements of fishers are more flexible than was previously thought.
It is hard to say whether or not new trapping regulations have significantly affected the increase in fisher numbers in the Commonwealth. In November 1996, the residents of Massachusetts passed the Wildlife Protection Act, also known as “Question One,” which outlawed the use of leg hold traps and conibear (body gripping) traps in the state. During the November trapping season, fishers can currently only be trapped using box traps and the animals must then be humanely destroyed. The figures for the 1995-1996 trapping season (before the Wildlife Protection Act) indicate that 226 fishers were harvested in Massachusetts. With the new regulation in place, the 2000-2001 season recorded the fisher harvest at 124 animals.
FISHER AND HUMANS
Fishers are secretive and elusive creatures. They keep their distance from humans and, unlike other wildlife such as squirrels, raccoons, and skunks, they do not den under buildings.
FISHER AND DOMESTIC CATS
A domestic cat roaming in the wild could become food for a fisher. To protect cats from fishers, as well as coyotes, Great Horned Owls, cars, and disease, it is recommended that cats be kept indoors.
FISHER AND RABIES
Fishers may carry ticks, fleas and mange, and like all mammals they are susceptible to rabies.
FISHER AND STATE LAW
Relocating wildlife is illegal in Massachusetts (321 CMR 2.14  [b]) and is detrimental to the well being of wildlife as well as the public. Unknowingly, sick animals may be transported and released in other locations, causing the spread of disease. Animals released in unfamiliar territory have a hard time surviving. They must compete with resident animals, and they often have difficulty finding food and shelter. Furthermore, relocation is ineffective: each time a territory opens, there is always another fisher “waiting in the wings.”
It is also against state law (321 CMR 2.12  [a]) to possess wild birds and mammals. Wildlife rehabilitators are trained and licensed by the state to care for injured and orphaned wildlife. If you need the services of a rehabilitator, contact the Massachusetts Division of Fisheries and Wildlife at 508-366-4470, or Mass Audubon’s Wildlife Information Line at 781-259-2150.