Fisher (animal)

Fisher
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Mustelidae
Genus:	Martes
Species:	M. pennanti
Binomial name
Martes pennanti (Erxleben, 1777)
Range map

The fisher (Martes pennanti), also referred to as fisher cat, is a medium-sized mammal native to North America. It is closely related but larger than the American Marten (Martes americana). Names derived from aboriginal languages include pekan, pequam, and wejack. The fisher ranges across the middle of the continent extending from the boreal forest in northern Canada to the northern fringes of the United States. Its original range was much further south but it was hunted to near extinction in the 19th century. Restrictions on hunting and trapping have resulted in a resurgence of the species to such an extent that it is now considered a pest species in some urban areas of New England.

The fisher is agile in trees and has a slender body that allows it to pursue prey into hollow trees or burrow in the ground. Despite its name, this animal seldom eats fish.

Etymology

The name implies a diet of fish yet it seldom dines on aquatic organisms. Early Dutch settlers noted its similarity to the European polecat (Mustela putorius). Fitchet is a name derived from the Dutch word visse which means 'nasty'. In the French language, the pelt of a polecat is called fiche or fichet.

In some regions the fisher is known as a pekan, derived from its name in the Abenaki language. Wejack was derived from otchoek (Cree) and otochilik (Ojibwa) by furtraders. Other American Indian names for the fisher are tha cho (Chippewayan), meaning "big marten," and uskool (Wabanaki).

Taxonomy

The latin species name pennanti is named for Thomas Pennant who described the fisher in 1771. Buffon had first described the creature in 1765 calling it a pekan. Pennant examined the same specimen but called it a fisher apparently unaware of Buffon's earlier description. It wasn't until about 80 years later that Audubon determined that the two descriptions were in fact the same creature but he incorrectly placed it in the genus of Mustela. The fisher was eventually placed in the correct genus by E.M. Hagmeier in 1959.

Members of the genus Martes are distinguished by having four premolar teeth on the upper and lower jaws. Its close relative Mustela has only three.

Evolution

There is some evidence that ancestors of the fisher migrated to North America during the Pliocene era. Two extinct mustelids M. palaeosinensis and M. anderssoni have been found in eastern Asia. The first true fisher, M. divuliana has only been found in North America. There are strong indications that M. divuliana is related to the Asian finds which suggests a migration. M. Pennanti has been found as early as the Late Pleistocene era. There are no major differences between the Pleistocene fisher and the modern fisher. Fossil evidence indicates that the fisher's range extended further south than it does today.

Three subspecies were identified by Goldman in 1935, M.p. columbiana, M.p. pacifica, and M.p. pennanti. However, later research debated whether these subspecies could be positively identified. In 1959 Hagmeier concluded that the subspecies were not separable based on either fur or skull characteristics. Although some debate still exists, it is generally recognized that there are no extant subspecies of the fisher.

Description

A Fisher climbing a tree. Notice its stretched long body, and the visible egg underneath

Fishers are a medium-size mammal. Their body shape is long, thin, and low to the ground. They are sexually dimorphic with the male being larger than the female. Males are between 90 to 120 centimetres (35–47 in) in length and weigh between 3.5 to 5 kilograms (8–11 lb). Females measure 75 to 95 centimetres (30–37 in) and weigh between 2 to 2.5 kilograms (4–6 lb). The largest ever male fisher recorded weighed 9 kilograms (20 lb).

The fisher's fur changes with the season and differs between sexes. Males have coarser coats than females. In the early winter the coats are dense and glossy ranging from 30 mm on the chest to 70 mm on the back. The color ranges from deep brown to black although it appears to be much blacker in the winter when contrasted with white snow. From the face to the shoulders fur can be hoary gold or silver due to guard hairs that are tricolored. The underside of a fisher is almost completely brown except for randomly placed patches of white or cream colored fur. In the summer, the fur color is more variable and may lighten considerably. Fishers undergo molting starting in late summer and finishing by November or December.

Fishers have five toes on each foot with unsheathed, retractable claws. Their feet are disproportionately larger than their legs which makes it easier for them to move on top of snow packs. In addition to the toes, there are four central pads on each foot. On the hind paws there are coarse hairs that grow between the pads and the toes which gives them added traction when walking on a variety of surfaces. Fishers have extremely mobile ankle joints which can rotate their hind paws almost 180 degrees allowing them to agilely move through tree branches and climb down trees head first.

A circular patch of hair on the central pad of their hind paws marks plantar glands that give off a distinctive odor. Since these patches become enlarged during breeding season there is some speculation that they are used for communication for reproduction.

Hunting and diet

Face of a fisher.

Fishers are generalist predators. They will feed on any animal they can catch and will eat carrion. They are also known to supplement their meat diet with insects, nuts, berries, and mushrooms. Their primary prey includes snowshoe hare and porcupine. Since they are solitary hunters their choice of prey is limited to their size. Analyses of stomach contents and scat have found evidence of birds, small mammals and even moose and deer. The latter food sources shows that they are not averse to eating carrion. Fishers have been observed to feed on the carcasses of deer left by hunters.

Fishers are one of the few predators that seek out and kill porcupines. There are some stories in popular literature that fishers can flip a porcupine onto its back and "scoop out its belly like a ripe melon." As early as 1966, this was identified as an exaggerated myth. However, observational studies show that fisher will make repeated biting attacks on the face of a porcupine and kill it after about 25-30 minutes.

In some areas fishers can become pests to farmers because they will get into a pen and kill large numbers of chickens. Fishers have also been known to eat feral cats and dogs and small pets left outdoors. However, a study done in 1979 examined the stomach contents of all fishers trapped in the state of New Hampshire; cat hairs were found in only one of over 1,000 stomachs. Attacks on domestic cats may be documented, but zoologists suggest a bobcat, coyote, or dog is more likely to prey upon domestic cats and chickens.

Reproduction

Female fishers have a somewhat unusual breeding cycle. They first breed at one year of age. The fisher breeding season spans from late February through late April. There is a ten-month delay after breeding before implantation of the blastocyst phase of the embryo occurs, resulting in a 352-day gestation period. Litters are produced annually. The young are born in dens high up in hollow trees. Adult females may mate just six to eight days after giving birth.

Kits nurse for about four months and begin to eat meat before they are weaned. The kits' cries resemble that of a kitten.

A closup of a fisher stretching and investigating.

Distribution

Being arboreal, fishers were once found in forests, most often in coniferous or mixed forests, throughout North America. Today they are found only in parts of its historical range including much of Canada, and as far south as the Sierra Nevada in California to the Appalachians in West Virginia and north to New England, as well as in southern Alaska. They avoid open spaces. Fishers are solitary, only associating with other fishers for mating purposes. Recent studies, as well as anecdotal evidence, suggest that the highly adaptable fishers have begun making inroads into suburban backyards, farmland, and even semi-urban areas in Michigan and Pennsylvania as well as Ontario and Quebec in Canada.

The fisher at present are in low density in the Rocky Mountains, where most populations are the result of reintroductions.

In recent years, they have spread from Vermont into southern New Hampshire, Massachusetts, and Rhode Island, and have recently been artificially reintroduced into dozens of areas across the United States, including in Montana, Oregon, and Washington. As of 2009, reports indicate the fisher population has returned to areas from which they were previously extirpated, such as Connecticut, the Hudson Valley in New York, and New Jersey. The fisher has been seen in Alaska since the 1990s.

On 27 January 2008 fishers were reintroduced into the Olympic National Park in Washington State. Fishers, native to Washington, have not been known to exist anywhere in the state for generations because of overtrapping in the 1800s and early 1900s and the loss of old-growth forests.

Conservation status

Fisher raiding a farmer's duck coop.

During the past two centuries fisher populations have been extirpated across parts of North America due to what was once a high demand for their furs. Furriers were paying up to $345 per animal in 1922. Their soft brown pelts can still fetch sometimes high prices. Fishers are shy, secretive, and difficult to breed in zoos. However, on March 23, 2008 three fisher kittens were born at the Minnesota Zoo in Apple Valley, Minnesota.

In New England, fishers, along with most other furbearers, were nearly exterminated due to unregulated trapping until the mid-1800s. Also, much of the forest habitat preferred by the fisher was put to agricultural use. Some measure of protection was afforded in the early 1900s, but it was not until 1934 that total protection was finally given to the few remaining fishers.

The fisher was again abundant enough in 1962 to warrant an open trapping season. During the early 1970s the value of fisher pelts soared, leading to another population crash in 1976. After a couple of years of closed seasons fisher trapping re-opened in 1979 with a shortened season and restricted bag limits. The population has steadily increased since then, with trappers taking about a thousand fishers per year in the late 1990s, despite a much lower pelt value.

Fishers were reintroduced into several states including Pennsylvania, Connecticut and West Virginia after being nearly wiped out by trapping and habitat destruction in much of North America, sometimes in an effort to control porcupine populations.

Several baby fishers were born on May 23, 2009 in a remote section of Olympic National Park in Washington State, a region that had lost all known fishers by the early 1900s due to trapping. Reintroduction of the species started in January 2008.

Literature

There are very few stories that are feature the fisher as a central figure, likely due to its shy and elusive nature. There are some exceptions. In The Audubon Book of True Nature Stories, Robert Snyder relates a tale of his encounter with fishers in the woods of the Adirondack Mountains of New York. He recounts three sightings, including one where he witnessed a fisher attacking a porcupine.

In Winter of the Fisher, Cameron Langford relates a fictional encounter between a fisher and an aging recluse living in the forest. The recluse frees the fisher from a trap and nurses it back to health. The fisher tolerates the attention, but being a wild animal, returns to the forest when well enough. Langford uses the ecology and known habits of the fisher to weave a tale of survival and tolerance in the northern woods of Canada.

References

• Fergus, Charles (2006). Wildlife of Virginia and Maryland and Washington. Stackpole Books. ISBN 0811728218.
• Powell, Roger A. (1993). The Fisher: Life History, Ecology, and Behavior. Univ of Minnesota Press. ISBN 9780816622665. {{cite book}}: Unknown parameter |month= ignored (help)

External links

• Fisher Cat Screech Online community of fisher cat sightings, sounds, and videos.
• Living with Fisher in Massachusetts Massachusetts Dept. of Fisheries, Wildlife & Environmental Law Enforcement.