Related Biomes
Fisher
Fisher, Martes pennanti
The fisher is a large member of the weasel family that is native to North America. It is a forest-dwelling predator that currently occupies much of the boreal forests of Canada. Its range extends as far south as the forested areas of the northeastern U.S., the northern Great Lakes, and mountainous portions of the western U.S. Prior to European settlement of North America, this range extended further south into Illinois, Indiana and Ohio, as well as the central and northern Appalachian mountains; however, increased trapping activities by fur traders in the nineteenth and early twentieth centuries helped to extirpate these animals from this region. During the late Pleistocene, the fisher's range extended even further south into Alabama and Georgia.
A fisher (Martes mennanti) photographed at night while trying to take bait. Credit: U.S. Fish and Wildlike Service
Length: Males 90-120 cm (3-3.9 ft), Females 75-95 cm (2.5-3.1 ft)
Weight: Males 3.5-5.5 kg (7.7-12.1 lb), Females 2.0-2.5 kg (4.4-5.5 lb)
Source: Powell et al. 2003
Physical Description:
Fishers are medium-sized carnivores with moderately elongated bodies, short legs, wedge-shaped faces and wide, rounded ears. They are covered in dense, dark-brown or black fur, and have long, bushy tails. They also have large, furry paws that enable them to walk on top of the snow, and five sharp, curved, semi-retractable claws on each foot. As with other mustelids, fishers have several scent glands.
Fishers prefer mesic (moderately moist), coniferous forests, but are also found in mixed growth and deciduous forests. They prefer areas with abundant understory growth and plenty of hollow logs and trees for denning. Whenever possible, they will choose closed-canopy habitats over open areas, although a few instances of open-area-use have been recorded (Meyer 2007).
Fishers are generalist predators and commonly eat rodents, rabbits, and birds, and occassionally fruit, insects and carrion (Bowman et al. 2006). Their diet is fairly flexible and depends in large part on the types of prey that are locally available and abundant. In many areas, this includes both snowshoe hares and porcupines, and the fisher is one of the few predators capable of killing porcupines. Other common prey include squirrels, mice and shrews, and carrion typically consists of large mammals such as deer or moose (Powell 1981).
Fishers are primarily solitary animals outside of the breeding season. They have active periods during both the day and night and have been found to be capable of traveling long distances over short periods of time - as much as 90 km in 3 days (Powell 1981). They tend to use a variety of sites for sleeping, such as hollow trees, logs, stumps, brush piles, rocks falls, abandonded beaver lodges and holes in the ground, and typically a site is only used for a short period of time before the animal moves on to a new sleeping site. The majority of fisher activity occurs at ground level, although they are capable of climing trees - a skill that is used to maneuver porcupines into an attackable position. The fisher's agility and long, low body shape make it uniquely adapted to prey on porcupines, which they accomplish by repeatedly biting the porcupine's face - the only portion of that animal that is not protected by quills. Other large predators are adapted to attack from above, which would bring them into contact with the porcupine's quills.
During the late Pleistocene, fishers occupied a much larger and more southerly range than they currently enjoy. Remains of this animal have been recovered from late Pleistocene sites as far south as Arkansas, Alabama and Georgia, as well as from sites throughout the eastern half of the U.S.
As with other cold-climate adapted species, fishers migrated northwards as the glaciers retreated, following the geographic shift of their preferred habitats. These animals were present throughout most of Canada and the northern United States for much of the Holocene, until overtrapping and habitat destruction in the nineteenth century significantly reduced their population density and led to extirpation in most of the northern United States. Recent efforts to reverse some of these historic processes have allowed fishers to return to portions of their former range, but they are still absent from much of the United States.
Fisher remains have been recovered from late Pleistocene sites in Missouri (Bat Cave, Aarnold Research Cave and Brynjulfson Cave #1), Indiana (King Leo Pit Cave, Megenity Peccary Cave, Prairie Creek and the Carter site), Ohio (Sheriden Pit) and Wisconsin (Raddatz Rockshelter), suggesting that this animal ranged freely across the Midwest during the last ice age.
- Despite its name, the fisher rarely eats fish.
- It is likely that the name "fisher" comes from early European immigrants who noted its physical similarity to the European polecat, which is commonly called the fitchet or fitche (Brander and Books, 1973)
Bowman, J., D. Donovan, and R. Rosatte. 2006. Numerical Response of Fishers to Synchronous Prey Dynamics. Journal of Mammalogy 87:480-484.
Brander, R. B. and D. J. Books. 1973. Return of the fisher. Natural History 82: 52-57.
Powell, R. A., S. W. Buskirk, and W. J. Zielinski. 2003. Fisher and Marten, in Wild Mammals of North America, 2nd edition, edited by G. A. Feldhamer, B. C. Thompson, and J. A. Chapman, pp. 635-649. The Johns Hopkins University Press, Baltimore, MD.
Meyer, Rachelle. 2007. Martes pennanti. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/ [2012, May 8].
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