Fisher Cats

Wild Animals/fisher cats

Expert: Jonathan Wright – 6/17/2004

Question
These are the fishers found in the northern US.

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Answer
Dear Misty

Thanks for your question. I have tried to find details of controlling fishers, but to no avail. This is probably due to their declining population and the need to conserve fishers. I used several books and websites. I used ‘fisher Martes pennanti and pest’ in google and vivisimo.

The most detailed website I found is: http://www.ecosystem.org/fisher/fnlfishr.pdf. I have compiled the following information from this site and several other sources.

Description: The fisher, Virginian polecat or pekan (Martes pennanti) is 41-80 cm long with a 25-43 cm long tail, 4-5cm ear and 9-16 cm hind foot. The male is much larger than the female and weighs 2.6-8.2 kg and the female 1.3-3.2 kg. It is medium to dark brown to nearly black on the head, neck and shoulders, with white-tipped hairs over most of its body, giving it a frosted appearance; there is gold to silver hoariness on the head and shoulders. There is a variable cream chest patch and there may be small white spots, around the genitals, on the brown underparts. The fur comprises two layers: long guard hairs cast off the rain and protect against physical damage, and a denser underfur retains an insulating blanket of air around the body core. In spring much of the fur is moulted to leave a shorter, coarser summer coat, but in autumn the thick pelt grows again to see thee fisher through the winter. The legs and tail tip are black. It has a long, slim body, pointed snout, rounded ears, short legs and bushy tail. There are 38 teeth and 8 mammae.

Tracks: The tracks are larger than those of a mink or marten. They are wider than they are long, with the claws showing. They are 5 cm wide on dirt and over 6 cm wide on snow. They may end abruptly when a fisher climbs a tree.

Habitat and location: It lives in dense, extensive mature coniferous and mixed hardwood forests and cutover wilderness areas, with an extensive overhead canopy. It is most abundant in dense lowland forests and spruce fir forests, but avoids open areas. It ranges over the southern tier of the Canadian provinces south to northern California (Sierra Nevada) and in the Rocky Mountains to Utah. In the east it ranges to northern New England and New York.

Habits: It is primarily nocturnal, mostly near sunset and sunrise for 2-5 hours, when it mainly searches for food, but is active day and night. It is at home on the ground and in trees. It dens in hollow trees, stumps and logs, rocky crevices or underbrush or a digs a hole in the snow as a temporary den, but does not burrow. It may use abandoned beaver lodges. It shifts sites occasionally. Its home range is about 38 square km for males and 15 square km for females. There is little overlap between the ranges of animals of the same sex, but extensive overlap between the ranges of opposite sexes. The fisher is solitary except in the breeding season. The range is larger in winter when food is scarce. The population density is one per 2.6-7.5 square km, but may be as low as one per 200 square km. Daily movement may be 1.5-3 km a day, but one individual covered 90 km in 3 days. The fisher uses well-established trails or running on fallen logs and moving between trees, from branch to branch. It walks on the soles of its feet and climbs and swims well. The claws are partly retractable and the hind paws can be turned 180°, so that they can serve as anchors when driven into the bark of a tree. The fisher moves quickly and with persistence on the ground. The fisher has large surfaces on its soles to help it run on old snow without sinking in. If disturbed, it hunches its back like a cat and may hiss, growl, snarl or spit and can give off an offensive odour. Plantar glands on the feet produce an odour, which may be used for communication during reproduction.

Food: It feeds primarily on snowshoe hares, rabbits, porcupines, squirrels, mice, shrews, raccoons and other small mammals, as well as small to medium-sized birds, eggs, reptiles, insects and carrion and fungi, fruits, fern tips and other plants. It generally forages in a zigzag pattern, constantly investigating places where prey may be concealed and may dig holes to find food. It captures and kills hares and other prey with a quick rush and a bite to the back of the neck or head. It may wrap its body around a hare and hang on with its back legs. Fishers do not need to be hungry to kill prey. The fisher may have gained its name from the mink’s habit of fishing being mistakenly ascribed to the fisher; fish only forms a small part of the fisher’s diet; some scientists feel that the name derives from the fisher stealing bait fish from traps. It may store food. It has been calculated that it requires a porcupine every 10-35 days, a snowshoe hare or 1 kg of deer carrion every 2.5-8 days, 1-2 squirrels, 20 voles or 7-22 mice a day. A fisher may kill deer, which have sunk into the snow and eats more carrion in winter, presumably when other prey animals hibernate. When a fisher feeds on a deer carcass, it often finds a resting den nearby and repeatedly returns to the carcass to feed.

The fisher is one of the few predators that will feed on porcupines. The fisher stands low to the ground, due to its short legs, and can direct an attack to a porcupine’s face, which is relatively unprotected. The fisher circles the porcupine on the ground, taking advantage of any chance to bite its face. The porcupine keeps circling as it tries to keep its back and tail toward the fisher and to seek protection for its face against a log or tree. If the porcupine flees to a tree, the fisher attacks in the tree and can no longer be thrown off. If the fisher delivers enough solid bites to the porcupine’s face, the porcupine suffers blood loss, shock or cannot protect itself. The fisher then overturns the porcupine and rips it open to feed along the unprotected abdomen, leaving behind only a few bones, the skin and the spikes. A successful kill may take over 30 minutes and the fisher may have enough food for over 2 weeks. Occasionally the quills may injure or kill a porcupine.

Scat: The scat is 10-15 cm long and is dark, cylindrical and often segmented. It may show fur, bone, berries, nuts and porcupine quills.

Parasites: Fishers harbour fleas, ticks and various intestinal parasites.

Breeding: The fisher shows low reproductive capacity, which is not helped by the decreasing population. Normal spacing mechanisms seem to break down in the breeding season (late February-May), with females probably mating 3-9 days after giving birth. Males leave their territories to seek as many females as possible and may come into physical conflict with one another. Fishers mark elevated objects with their faces, urine and musk. They are probably polygamous and a female may mate with more than one male. Courtship may last 1-7 hours. 1-6 young, usually 3, are born in February-May, after a gestation period lasting 11-12 months, due to delayed implantation of 9-10 months. Post-implantation embryonic development lasts 30 days. The mother rears the young alone, using a series of dens high in hollow trees with an entrance 1.2-1.5 m above the ground or, perhaps, in rock crevices. The newborn young is helpless, blind and only partly covered with fine hair. It weighs under 40 g. The eyes open at 7 weeks and the young can walk at 8-9 weeks and are weaned at 8-16 weeks. They stay in the den for up to 3 months and the family breaks up in autumn, in the fifth month. Females reach adult weight after 6 months and males after 1 year. Fishers become sexually mature at 1-2 years, with females have their first litters when 2 years old. Fishers may live for 10-18 years.

Fishers and people: The fisher is a valuable fur-bearer, with female skins being especially prized. The fur is tough, due to the superb insulation provided by the thick, silky underfur. The fisher was eradicated in many areas in the early 20th century. The name may derive from the old English (‘fiche’), Dutch and French (‘fichet’) words for the European polecat and its pelt. The fisher is beneficial to forests because it kills porcupines, with porcupines making up to 255 of a fisher’s diet. When fishers declined in numbers, the increase in porcupine populations led to increased destruction of new plantations. It can be dangerous to dogs. Populations have been depleted due to loss of habitat, through logging, as it requires extensive wilderness. Widespread closed seasons and other protective regulations were initiated in the 1930s, with reintroductions in the 1950s and 1960s in some areas of the USA. It is protected in some states.

I have tried to find information about pest control, but all the sites indicate that the population of fishers is falling and that the animal requires protection, rather than persecution. I would recommend you to contact your local wildlife protection organization, so that trained staff can either help you understand the value of the fisher or help trap the fishers and remove them to more suitable sites.

I’m sorry that I haven’t answered your question in the way you would have liked. I am a member of the London Bat Group and know that many people dislike bats. All the species of British bats are protected and members of the public are not allowed to control bats without a licence. From the information I have gained about fishers, it seems that the same principle applies. It seems unlikely that you will be able to take the law into your own hands in controlling fishers and will probably need a local wildlife organisation to help.

All the best

Jonathan