About Fishers

Fisher at Ipswich River Wildlife Sanctuary © Phil Brown
© Phil Brown

Despite commonly being referred to as "fisher cats," a fisher is not a feline nor do they catch fish. Fishers (Martes pennanti) are the second-largest member of the weasel family found in Massachusetts, after the North American River Otter.

What is true about this shy and elusive mammal is its hunting prowess: fishers are one of nature's few porcupine predators.

Identification

As with other members of the weasel family, fishers have a long, slender body and a low profile when moving along the ground. Their coat is dark brown, dense, and glossy. Males are generally twice the size of females and weigh up to 30 pounds.

Both male and female fishers average 32-40 inches in length, with their tapering tail accounting for one-third (12-16 inches) of that total! Their legs are short and stout. Fishers have partially retractable claws that make them agile and speedy tree climbers, capable of jumping up to 7 feet between trees.

Population

Fishers were extirpated (forced out) of southern New England by the 19th century. This was primarily due to the fact that, during the 1700s and 1800s, loggers and farmers cleared most of the forests in the northeast and unregulated trapping was rampant. However, in the late 1800s, people began abandoning their farms for other prospects. Over the next several decades, the forests gradually returned to the landscape and the fishers followed.

Intentional reintroduction efforts also helped fisher populations rebound. In the 1950s, with permission from each state, logging companies 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—and fishers are the only species to deliberately target porcupines as prey. 

Fisher resting in a tree © Joshua Goddard
Fisher © Joshua Goddard

In eastern North America, fishers are now found in southern Canada, New England, and New York, and in scattered locations in Pennsylvania, West Virginia, and Virginia. They may be potentially found in practically every community in Massachusetts.

Home Range

The average home range of a fisher is around 15 square miles in size. For males, that area is typically between 6-32 square miles. While a female's home range tends to be smaller, averaging 5 square miles, it's more stable across the seasons than a male's. Since they prefer to avoid traveling in large, open areas, fishers opt for mixed forest habitat with heavy canopy cover. They can travel up to 18 miles in a single 24-hour period.

Behavior & Sounds

Secretive and elusive by nature, fishers like to keep their distance from humans. They are solitary creatures except during their brief mating season in late winter, and are active both night and day throughout the year.

Like most members of the Mustelidae (weasel family) found in New England, fishers are pretty quiet creatures unless they are in the grip of a predator. They use scent to locate prey, and successful hunts require silence and stealth. You may have come across videos and audio recordings online of loud, unearthly "screaming" sounds that people have attributed to fishers. However, the nighttime vocalist in these videos is nearly always a Red Fox—and never a fisher.

Food & Diet

Fisher investigating fruits inside a shrub © Ilana Eubank
Fisher © Ilana Eubank

Fishers are mostly carnivores, although they consume berries and fruit when available. They will eat rabbits, snowshoe hares, squirrels, raccoons, mice, reptiles, amphibians, insects, carrion (dead or decaying animal flesh), and occasionally outdoor 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's worth the effort. While on the ground, 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. To avoid the quills, the fisher eats its prey starting at the head, neck, or underbelly.

Life Cycle

Breeding takes place in March or April when females are 1-2 years old; males do not help rear the young. After a delayed implantation period of 10 or 11 months, the blastocyst (earliest stage of the embryo) is implanted in the womb, possibly stimulated by changing day length. Once that happens, the embryo develops in only six weeks.

Fisher moms are choosy when it comes to dens. They look for tree cavities that have an opening large enough for the mother to enter, but too small for predators that may harm her kits. And since females are able to mate again within just a few days after giving birth, mothers must guard against male fishers as well.

Kits are generally born in March in litters of 1-6 individuals. Born blind and with very little fur, the helpless kits are dependent on their mother for the next few months. Young fishers begin to capture their own prey around four months of age, and disperse by the time they are five months old.

Situations & Solutions

Fishers avoid humans and don't den under buildings. That being said, fisher sightings have increased significantly since 2000, which may cause concern among homeowners. Information about fisher sightings & encounters >