Douglas H. Domedion, CC BY-SA 4.0 <creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
By Misi Stine, Environmental Educator and member of the MN Herpetological Society
Fishers (Pekania pennanti) are curious critters for many, partly because sightings are considered rare, even though they are thought to be common, with an estimated population of 10,000 in Minnesota. They are found throughout the northern forested areas of Minnesota, with additional documented animals in the prairies to the west and the river valleys in the southeast.
Fishers are members of the weasel, or Mustelidae, family; with that classic elongated tube-shaped body, they look like a larger version of their close cousins, the pine marten, and the mink. Fishers have dark brown to black fur, with a bushy tail, and may have white to cream color patches on their chest. Adults can be 24-30 inches long. A female’s average weight is 6 to 8 pounds, while a male may weigh up to 18 pounds.
Fishers are arboreal and known for their predatory skills. They eat snowshoe hares, rodents, and deer fawns and are one of the few active and successful hunters of porcupines. In addition, they will also consume berries, nuts, and even carrion. Here are a few other fascinating facts about fishers.
Fishers are only found in North America and are known as the fastest tree climbers on the continent. Fishers are not known to prey on fish as a regular part of their diet. Their name comes from the Early European settlers that thought they looked like the European polecat, referred to as “fitch.” The Ojibwe traditionally called them “tha-cho” which means “Big Marten.”
Female fishers give birth in the spring to 1-5 young. Within days, they mate and become pregnant again. However, the embryos do not implant and grow into fetuses until two months before they are born the following spring, a process known as delayed implantation. In total, their gestation period is 350 days! These fierce mesopredators are not easily preyed upon. However, bobcats, which compete for the same prey and habitats, are known to kill young and adult fishers occasionally.
Mount Rainier National Park from Ashford, WA, United States, Public domain, via Wikimedia Commons
If you would like to manage your forests for suitable habitats for this species, here are some things to consider. They prefer extensive continuous old-growth forests, but they will adapt to the forest edge habitat and younger forest types. However, they do avoid open areas. Their denning sites include hollow trees, old porcupine dens, old beaver lodges where the water has dried up that are no longer occupied by the original residents, slash piles, and rock crevices.
Olympic National Park, Public domain, via Wikimedia Commons
I have included a link to a webinar that is part of the Minnesota Outdoor Skills and Stewardship Series by the Minnesota DNR from September 2022, which discusses this elusive critter in more detail and the research the Minnesota DNR is currently engaged in: youtube.com/watch?v=tLF1jnmCRdg
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