The fisher (Martes pennati), also known as the fishercat, pekan (French), otchock (Cree), otshilik (Ojibwan), and historically as the wejack (early European settlers), is a member of the weasel family. The variety of names attributed to this animal hints at its wide northern distribution. Other similar and closely related animals include the pine marten and mink.
The common name fisher is likely to have derived from early European settlers in their acknowledgment of the animal's superficial resemblance to the European polecat which is sometimes referred to as the fichet or fitche. In 1794, Samuel Williams described the fisher in his publication, The Natural and Civil History of Vermont, as a "fierce and ravenous" animal "of great activity and strength." He wrote on to say that the fisher could not "be tamed or made to associate with our common cats."
Although the latter of these statement may be true, this relatively small, forest dwelling carnivore is often characterized by many as being more savage than is actually deserved. Whereas the fisher has always been valued as a fur resource, it is only in more recent times that its predatory nature has become an appreciated part of Vermont's healthy, functioning ecosystems.
Fisher primarily reside in coniferous or mixed hardwood forests and particularly prefer uneven- aged forest containing snags and multiple fallen trees. These areas provide ample denning opportunities, and importantly, offer higher concentrations and varieties of prey.
Although food availability is recognized as the dominant attribute of fisher habitat, the use of an area is also believed to be dictated by the presence of large tracts of continuous overhead cover. Due to its northern distribution, the fisher's mobility is often restricted by deep fluffy snow. Forest canopies, which provide thick overhead cover, reduce accumulated snow depths, thus increasing mobility and improving foraging effectiveness.
Except during the breeding season, fishers are solitary. Females will defend their home ranges from other females, but will allow male territories to overlap with their own. The home range size of an adult female varies from three to eight square miles.
Similarly, males also defend their home ranges from other males but not from females. Adult male home range size varies from six to 15 square miles. While females typically stay within their home range throughout their life, all territorial behaviors breaks down for males while they roam in search of mates.
Secure inside a tree cavity den, a litter of kits (one to four) is born every March. Blind, helpless, and sparsely furred, the young are completely dependent on the female, who cares for them with no assistance from the male.
Kits are fully furred within 18 days, and their eyes begin opening at 53 days old. At about four months of age, they are completely weaned, mobile and are taught to kill prey on their own. At five months, when they are nearly full-grown and are effective hunters, the young begin dispersing from their mother's care.
Both males and females are capable of reproducing at one year of age. In Vermont, fishers commonly attain the age of ten years.
In as little as one week after giving birth, an adult female will periodically leave her dependent, newborn kits in search of a new mate. This breeding behavior usually occurs from late March through April. One female will likely find many suitors.
After mating, the fertilized egg remains in limbo through a process known as delayed implantation. During this process, all development of the embryo ceases for approximately ten to 11 months. After this time, the fertilized egg is implanted into the uterus wall and development of the embryo begins.
Post implantation gestation is approximately 30 to 60 days while pre implantation averages about 352 days. Females, therefore, spend the vast majority of their life in some stage of pregnancy.
Contrary to its name, the fisher does not typically eat fish. Its feeding behavior is best described as opportunistic; it feeds on whatever is seasonally abundant and readily available.
Primarily carnivorous, it will eat a variety of small to medium sized mammals, including mice, moles, voles, shrews, squirrels, muskrats, woodchucks, snowshoe hares, and occasionally even fawns.
The fisher has also been known to consume a variety of birds, reptiles, amphibians, and insects. Apples, cherries, raspberries, beechnuts, and acorns are also significant.
The fisher's appetite for porcupine is unique. There is much speculation as to how a fisher accomplishes this prickly meal, but as evidence suggests porcupines are most certainly a routine part of their diet. A fisher likely crowds the porcupine to the outer limits of a tree's branches, forcing it to fall. The dazed and probably injured porcupine is then more susceptible to an attack on the ground. Repetitive attacks to the unquilled face also help. Either way, this is proof of the fisher's amazing agility aloft in the trees or on the ground.
The fisher is active both day and night, with heightened activity occurring in the early morning and late evening. It will travel long distances during short periods in search of food. One radio-collared male, for example, traveled over 60 miles in a three-day period.
While wandering, a fisher will periodically stop to investigate possible food sources such as porcupine dens. In areas where prey is more abundant and predictable, such as in dense coniferous forest, it often zigzags back and forth, thereby flushing possible prey from its hiding cover.
While hunting, its body temperature falls forcing it to seek the warmth of shelter afterwards. Temporary dens are most often found under logs, root wads, brush piles, and in the cavities of hollow trees or beneath the snow.
While the fisher will eat domestic cats, the occurrence of cat in their diet is relatively low. One study conducted in north- central Massachusetts examined 169 scats and 57 gastrointestinal tracts of fishers in attempt to determine their seasonal food habits. Even though domestic cats were common in the semi-rural study area, cat remains were identified in only 2% of the samples collected.
Although the threat of a fisher attack is low, concerned cat owners can reduce the chance of an attack by limiting their cat's outdoor activities. Cats are most susceptible to fisher predation during the late evening and early dawn hours of spring and fall when fishers are most active.
Outdoor cats are also potential prey for a variety of animals including coyote, fox, bobcat, and great-horned owl, but are also susceptible to disease, cars, and parasites. The average life expectancy of an outdoor cat is two to five years while an indoor cat may survive 17 years or more.
Cat owners must understand that when their pets roam at large, they pose a significant threat to native wildlife. It has been estimated that domestic cats kill hundreds of millions of birds each year.
The Vermont Fish & Wildlife Department strives to conserve the fisher in order to maintain ecosystem integrity while providing diverse opportunities to ethically view, harvest, and utilize this unique furbearer. Within the last 200 years, however, their distribution has varied dramatically as a result of human influence. The landscape scale removal of forests, European settlement, and unregulated trapping characteristic of the 1800s, severely reduced or eliminated fisher populations from much of their southern range including Vermont. After successful reintroduction efforts, they are now once again, present in our state.
Today, fishers are common throughout Vermont and are found in virtually every town. Trapping is permitted during a heavily-regulated season each year, and the health of the population is monitored annually by information collected from trapper mail surveys and by physical examination of the age and sex structure of fishers.