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Monday Mustelid - Martes pennanti Edition

Switching gears from dinosaurs to mustelids!

The Fisher (Martes pennanti) can be found only in North America, primarily in the northern forests of Canada and the northern United States. Their range extends as far north as Great Slave Lake (the deepest lake in North America) and as far south as Oregon, with isolated populations in the Appalachian Mountains and Sierra Nevada. The Fisher is sometimes referred to as a “fisher cat,” but it is not a cat, and should not be confused with the Fishing Cat. Some indigenous language names for the Fisher include wejack, pekan and pequam. Fishers were trapped for their fur, the heavy hunting resulting in their extirpation from much of their historical range.


Fishers are the largest species in the Martes genus, being about the size of domestic cats. Their coats vary in color depending on the season: in winter, they are dark brown or black. During the summer, they can be much lighter. Males tend to have coarser coats than the females, and are a little larger in size, weighing up to 13 pounds (6 kg) and measuring 47 inches (120 cm) in body length. Females weigh only 6 pounds (2.5 kg) and grow up to 37 inches (95 cm) in body length. Fishers have large feet relative to their size and the length of their legs, making it easier for them to walk on the surface of the snow. They are extremely flexible and great climbers, and their hind ankles can rotate 180 degrees to let them climb down trees head first.

The diet of the Fisher is fairly general and depends on what kind of prey animals live in their territories. They are crepuscular (being active during dusk and dawn) and hunt alone, which limits the size of the prey they will attempt to take, although being mustelids they are capable of taking down animals as large as porcupines and snowshoe hares. Fishers are one of the few predators that regularly hunt porcupines, repeatedly attacking the porcupine’s face and finally killing it after about 30 minutes. In rare cases, they have been known to take wild turkeys, bobcats, and even lynx. They will eat carrion and supplement their diet with insects, berries, nuts and mushrooms.


Fishers typically only seek out each other’s company for breeding purposes, being solitary animals. Mating usually takes place during the spring, and female Fishers delay implantation of the fertilized embryos until February of the next year, with an active gestation time of about 50 days. This makes total pregnancy last for about a year, after which they give birth to one to four kits. The kits are totally dependent on their mother for the first 8 weeks or so, after which they start to eat solid food. Kits tend to become intolerant of their litter mates when they are four or five months old, at which point their mother decides that it’s time for them to be on their own.


Because of the demand for their fur, Fishers were over-hunted and almost extinct in the southern part of their range. Strict measures have been put in place to prevent more over-hunting, although it is still legal to trap them in some areas. Farming Fishers for their fur has proven ineffective, as the fur must be “harvested” at the right time of the year, and declining prices as well as the nature of the Fisher’s reproductive cycle did not make it cost-effective. Fishers will rarely attack domestic animals, and in very few cases are known to attack humans, as they will fight back when threatened or cornered.


Source for all images used in this post.

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