---
title: "What the sources say about the Fisher | AnimalTracks.wiki"
description: "51 claims from the Fisher profile, each beside the words of the source that backs it."
image: "https://animaltracks.wiki/images/animals/fisher-1.webp"
canonical: "https://animaltracks.wiki/animals/fisher/sources/"
---

# What the sources say about the Fisher (*Pekania pennanti*)

> 51 claims from the Fisher profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Fisher](https://animaltracks.wiki/animals/fisher/)

## Martes pennanti. Animal Diversity Web.

https://animaldiversity.org/accounts/Martes_pennanti/

| The page says | The source says |
| :--- | :--- |
| climbs trees | Fishers are agile and speedy tree climbers (note: tagline) |
| hunts porcupines | Fishers hunt porcupines (note: tagline) |
| whose females spend almost all of their adult lives pregnant or nursing | So females essentially spend almost all of their adult life in a state of pregnancy or lactation. (note: tagline; pregnant or nursing = pregnancy or lactation) |
| Coniferous forests, also mixed and deciduous ones, from the Sierra Nevada of California to the Appalachians | Fishers prefer coniferous forests, but they are also found in mixed and deciduous forests. (note: stats.habitat) |
| from the Sierra Nevada of California to the Appalachians | from the Sierra Nevada of California to the Appalachians of West Virginia and Virginia (note: stats.habitat) |
| Mice, porcupines, squirrels, snowshoe hares, birds and shrews, plus some fruit | Fishers eat mice , porcupines , squirrels , snowshoe hares , birds , and shrews (note: stats.diet) |
| plus some fruit | They may also feed on fruits and berries, such as beechnuts and apples. (note: stats.diet) |
| Its embryos pause for 10 to 11 months and a mother mates again soon after giving birth, so a female is pregnant or nursing for almost all of her adult life | the embryos sit in suspended development for 10 to 11 months (note: stats.superpower) |
| a mother mates again soon after giving birth | Shortly after giving birth, females experience a postpartum estrus and mate again. (note: stats.superpower; ADW's 'So' follows this sentence and annual breeding, not the pause alone) |
| a female is pregnant or nursing for almost all of her adult life | So females essentially spend almost all of their adult life in a state of pregnancy or lactation. (note: stats.superpower) |
| The fisher belongs to the weasel family | Mustelidae badgers, otters, weasels, and relatives (note: Family line of the ADW classification table; the quote spans the table's rank and gloss.) |
| It has five toes on each foot and retractable claws. | Fishers have five toes on their feet, and their claws are retractable. |
| It is an agile, speedy tree climber, although it usually travels on the ground. | Fishers are agile and speedy tree climbers, but they usually move on the ground. |
| On average, males are the larger sex, with a body length of 900 to 1200 mm and a weight of 3.5 to 5 kg. | 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. (note: 3500 to 5000 g = 3.5 to 5 kg) |
| Females measure 750 to 950 mm and weigh 2 to 2.5 kg. | Females range from 750 to 950 mm in length and 2000 to 2500 grams in weight. (note: 2000 to 2500 g = 2 to 2.5 kg) |
| Only the fisher and the American marten are medium-sized predators that can climb well and also stretch their bodies out to follow prey into holes in the ground, hollow trees and other tight spaces. | 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 that look for prey their own size or smaller, though they can take bigger animals. | 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. |
| The menu includes mice, squirrels, snowshoe hares, birds and shrews, and they may also eat fruit and berries. | Fishers eat mice , porcupines , squirrels , snowshoe hares , birds , and shrews |
| they may also eat fruit and berries | They may also feed on fruits and berries, such as beechnuts and apples. |
| They also hunt porcupines, and Animal Diversity Web notes that this can help control porcupines, which damage timber by stripping bark and killing trees. | Fishers hunt porcupines , and can effectively control porcupine populations (porcupines are known to damage timber crops by debarking and killing trees). |
| Once a female's eggs are fertilized, the embryos stop growing for 10 to 11 months. | After fertilization, the embryos sit in suspended development for 10 to 11 months |
| Counting that pause, her pregnancy runs 11 to 12 months. | Overall, gestation lasts almost a full year, 11 to 12 months. |
| delayed implantation | delayed implantation (note: ADW reproductive-features term; definition from ADW glossary: a fertilized egg reaches the uterus but delays its implantation in the uterine lining) |
| the fertilized egg reaches the womb but delays attaching to its lining | a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months |
| The female then gives birth, to an average of 3 young, and soon afterward mates again. | 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. |
| So a female spends almost all of her adult life pregnant or nursing. | So females essentially spend almost all of their adult life in a state of pregnancy or lactation. |
| Newborns are blind, nearly naked and weigh about 40 grams. | Young fishers are born blind and nearly naked. Each weighs about 40 grams at birth. |
| Their eyes open after about 53 days. | The eyes open after about 53 days. |
| By four months old they can hunt for themselves. | By the time they are four months old, the young are able to hunt for themselves |
| The fisher is found nowhere but North America. Its range reaches south along California's Sierra Nevada and down the Appalachian chain, as far as West Virginia and Virginia, and it is absent from the prairies and the southern United States. | 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. |
| They prefer coniferous forest with plenty of hollow trees for dens. | Fishers prefer coniferous forests ... They also prefer habitats with many hollow trees for dens. |
| Each fisher keeps a home range of 15 to 35 square kilometers, averaging about 25. | Home range size varies from 15 to 35 square kilometers in area, averaging about 25 square kilometers. |
| Trapping for pelts once had a significant effect on their numbers | Fishers are trapped and killed for their pelts. Trapping, in the past, had a significant effect on fisher populations (note: text split below) |
| logging destroys the near-continuous conifer forest they prefer | Logging of forests greatly impacts fishers and fisher populations by destroying their preferred habitat--continuous or nearly continuous coniferous forests |
| In 2003 Animal Diversity Web reported that numbers seemed to have rebounded in parts of North America, including Michigan, Ontario, New York and some of New England. | 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. (note: ADW account last updated 2003-05-22 (To cite this page: Rhines, C. 2003)) |
| A male runs 90 to 120 centimeters long and weighs 3.5 to 5 kilograms. A female is smaller on average, at 75 to 95 centimeters and 2 to 2.5 kilograms. | 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. (note: converted units) |
| It belongs to Mustelidae, the family Animal Diversity Web describes as badgers, otters, weasels and their relatives. | Mustelidae badgers, otters, weasels, and relatives |
| Almost a full year: 11 to 12 months in all. For 10 to 11 of those months the embryo is on hold, picking up again late in the winter after mating. | 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. |
| Once a female fisher's eggs are fertilized, the embryos stop growing for 10 to 11 months | After fertilization, the embryos sit in suspended development for 10 to 11 months (note: vibe.reason) |
| dangerLevel: Medium | When startled, fishers may react aggressively to the perceived threat. (note: task #1246; Medium: can injure, but rarely seriously. ADW lists "injures humans: bites or stings" under negative impacts; pine marten stays Low (no such report).) |
| tags: climber | Fishers are agile and speedy tree climbers (note: task #1246; Climber tag definition: scaling tree trunks with hooked claws; ADW states the behaviour.) |

## AnAge entry for Martes pennanti. Human Ageing Genomic Resources, AnAge.

https://genomics.senescence.info/species/entry.php?species=Martes_pennanti

| The page says | The source says |
| :--- | :--- |
| In captivity, one fisher lived 14.3 years. | One specimen lived 14.3 years in captivity |
| In the wild, fishers may live up to 10 years. | In the wild, fishers may live up to 10 years |
| One fisher in AnAge's database lived 14.3 years in captivity. | One specimen lived 14.3 years in captivity |
| weightKg: 3.175 | Adult weight 3,175 g (note: task #1246; AnAge adult weight; ADW females 2 to 2.5 kg, males 3.5 to 5 kg, all Light. Name guess would have been Medium.) |

## Fisher. Virginia Department of Wildlife Resources.

http://www.dgif.virginia.gov/wildlife/information/fisher/

| The page says | The source says |
| :--- | :--- |
| A fox-sized relative of weasels that climbs trees, hunts porcupines and whose females spend almost all of their adult lives pregnant or nursing. | This species is the largest of the genus with a long fox-sized body |
| fox-sized, with short legs, a long body, small rounded ears and a long, bushy tail | a long fox-sized body, short legs, and ears that are small and rounded. The tail is long and bushy |
| Virginia lost its fishers by the late 1800s to habitat destruction, heavy trapping and shooting | fishers were extirpated from the state by the late 1800’s (habitat destruction, excessive trapping and shooting) |
| but in the past 20 years more have been sighted there, with evidence of breeding | In the past 20 years, more fishers have been sighted in Virginia, predominantly in the northern and western counties, including evidence of reproductive populations. (note: page last updated April 16, 2026) |

## Helgen & Reid (2018). Martes pennanti. The IUCN Red List of Threatened Species 2018: e.T41651A125236220.

https://doi.org/10.2305/iucn.uk.2016-2.rlts.t41651a125236220.en

| The page says | The source says |
| :--- | :--- |
| The IUCN Red List rates the species Least Concern, filed under its older name, Martes pennanti. | Least Concern (note: hand check: verify:quotes cannot read this category (GBIF species endpoint answers NE for taxon 41651); GBIF's distribution record for taxon 176684433 gives threatStatus LEAST_CONCERN citing this DOI. Title of the assessment is 'Martes pennanti'. Also stated by adw-fisher: 'IUCN Red List Least Concern'.) |
| Least Concern | Least Concern (note: conservationStatus; hand check, see above) |