Fishers are generally thought of as secretive and rarely observed. This may be changing in parts of their range as populations re-expand and become habituated to human presence.
Fishers have good senses of smell, hearing and sight. They communicate with each other by scent marking.
Communication Channels: chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Logging of forests greatly impacts fishers and fisher populations by destroying their preferred habitat--continuous or nearly continuous coniferous forests.
Zoos have had a hard time breeding fishers in captivity, but there has been some success. Because there are numerous thriving and healthy fisher populations, there has been little pressure or initiative to develop fisher breeding or maintaining programs in captivity.
In some areas of North America, such as Michigan, Ontario, New York, and some areas of New England, fisher populations seem to have rebounded in recent years.
Fisher populations in the southern Sierra Nevada have been proposed as candidates for protection under the Endangered Species Act.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
In recent years fisher populations in some areas, particularly southern Ontario and New York, have been recovering. In these areas they may be becoming habituated to human presence and venturing into suburban areas. There have been numerous reports of fisher attacks on domestic animals and even children. It is important to recognize that fishers are simply trying to find food and protect themselves. It is important to restrict access to garbage, pet foods, pets, and domestic fowl. When startled, fishers may react aggressively to the perceived threat. Diseased individuals may react unpredictably.
Negative Impacts: injures humans (bites or stings)
Fishers are trapped and killed for their pelts. Trapping, in the past, had a significant effect on fisher populations, but the problem is not as severe now. Fishers hunt porcupines, and can effectively control porcupine populations (porcupines are known to damage timber crops by debarking and killing trees).
Positive Impacts: body parts are source of valuable material
Fishers are important predators in their ecosystems. They are often in competition for food with foxes, bobcats, lynx, coyotes, wolverines, American martens and weasels. Fishers have a low incidence of diseases.
Fishers are predators, and most of their prey are herbivores. Fishers eat mice, porcupines, squirrels, snowshoe hares, birds, and shrews, and sometimes, other carnivores. They may also feed on fruits and berries, such as beechnuts and apples.
They have also been seen to eat white-tailed deer, though they are most likely scavenging a deer carcass.
Fishers and American martens are the only medium-sized predators agile in trees that also possess the ability to elongate themselves to seek prey in holes in the ground, hollow trees and other small areas. Fishers are solitary hunters, and seek prey that is their own size or smaller, although they are capable of taking on prey larger than themselves.
Animal Foods: birds; mammals
Plant Foods: fruit
Primary Diet: carnivore (Eats terrestrial vertebrates)
Fishers are found only in North America, from the Sierra Nevada of California to the Appalachians of West Virginia and Virginia. They range along the Sierra Nevada to their southernmost extent and south along the Appalachian mountain chain. They do not occur in the prairie or southern regions of the United States. Populations have declined in the southern parts of their range in recent history.
Biogeographic Regions: nearctic (Native )
Fishers prefer coniferous forests, but they are also found in mixed and deciduous forests. They prefer habitats with high canopy closure. They also prefer habitats with many hollow trees for dens. Trees typically found in fisher habitats include spruce, fir, white cedar and some hardwoods. Also, as would be expected, their habitat preference reflects that of their favored prey species.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: taiga ; forest ; mountains
Fishers can live up to ten years in the wild.
Range lifespan
Status: wild: 10 (high) years.
Males fishers are, on average, larger than females, with a body length of 900 to 1200 mm and a body weight of 3500 to 5000 grams. Females range from 750 to 950 mm in length and 2000 to 2500 grams in weight. Tail length of males is between 370 and 410 mm and tail length of females is between 310 and 360 mm. Their coats range from medium to dark brown, with gold to silver hoariness on their head and shoulders, and with black legs and tail. They may also have a cream chest patch of variable size and shape. Fur color and pattern varies among individuals, sexes and seasons. Fishers have five toes on their feet, and their claws are retractable.
Range mass: 2000 to 5000 g.
Range length: 750 to 1200 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Young fishers fall prey to hawks, red foxes, lynx and bobcats. Adult fishers are generally safe from predation.
Known Predators:
Little is known about mating in fishers. Copulation may last up to seven hours.
The breeding season is late winter and early spring, from March to May. After fertilization, the embryos sit in suspended development for 10 to 11 months, and resume developing late in the winter following mating. Overall, gestation lasts almost a full year, 11 to 12 months. The average number of young in a litter is 3, ranging from 1 to 6. Shortly after giving birth, females experience a postpartum estrus and mate again. Healthy females first breed at age 1, produce their first litter at age 2, and probably breed every year after that. So females essentially spend almost all of their adult life in a state of pregnancy or lactation. Males breed for the first time when they are two years old. Females reach adult weights at 5.5 months, whereas males reach adult weights after 1 year old.
Breeding interval: Fishers breed once per year.
Breeding season: Fishers breed in the late winter to early spring, from March to May. Breeding times vary with location.
Range number of offspring: 1 to 6.
Average number of offspring: 3.
Range gestation period: 11 to 12 months.
Range weaning age: 8 to 16 weeks.
Range time to independence: 5 (low) months.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; delayed implantation ; embryonic diapause ; post-partum estrous
Average birth mass: 35 g.
Average number of offspring: 2.5.
Average age at sexual or reproductive maturity (male)
Sex: male: 365 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 365 days.
Young fishers are born blind and nearly naked. Each weighs about 40 grams at birth. The eyes open after about 53 days. Young begin to be weaned at 8 to 10 weeks, but may nurse occasionally for up to 4 months after birth. By the time they are four months old, the young are able to hunt for themselves, and they disperse at least one month later. Most dens in which young fishers are raised are high up in hollow trees, and females may choose to move their young up to several times if the litter is disturbed. Male fishers do not help raise their young.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
