The Mink, the Marten and the Fisher
At 16:09 Aug 23rd, 2020 I saw my first American Mink (Neovison vison). I previously thought this critter to be the elusive and more terrestrial, Humboldt/Pacific Marten (Martes caurina ) but after a debate with a Humboldt local and mammal behavioral ecologist, discovered it was most likely the mink.
As I was visiting the Trinity River in Willow Creek, CA., I was amongst some rocks when I heard shouting of seeing a baby Otter. No, a Marmot!? NO A WEASEL! All false identifications. This quick mink was skimpering across sun-kissed sharp rocks and with my own two eyes I saw how he fully dived into the river and swam. He tucked his front and back limbs into his long torso mimicking the slithering of a water snake. A mammal, with fur, swimming like a snake! I couldn't believe it. His chocolate brown fur and charcoal eyes seemingly flew between water and land. His fur stuck to his body like scales, plus or minus a few cow-lick-like patches of fuzz. At one point I was less than a few feet away from him and at first he did not see me but when I clicked at him he locked eyes with me for a moment, then proceeded to effortlessly dive and swim and jump out of the water and onto treacherous rocks like he was playing jump rope. Of course, like the mad woman I am, I frantically followed him but lost him all too quickly. I didn't even get a photo. So, I'm left to scour the internet for a beautiful photo I did not take. In trying to ID this critter under my untrained eye, I was trying to look for unmistakable differences between two other species-the Humboldt Marten and the Fisher.
As my description above of the American Mink entails some of the physical movement, shape, color and texture of the mink there is still more to this creature. The American Mink (Neovison vison) has historically been a source for fur farming (but has drastically declined since the 80s), ranges in every state save Arizona, and their habitat is generally a blend of terrestrial and aquatic biomes (heavy emphasis on aquatic). Neovison vison can be physically differentiated from the Humboldt Marten and Fisher with its white chin, chest, and throat patches, thick soft and oily fur, short legs, pointy flat face, partially webbed toes, and half of the length is accommodated by the tail. Females are much smaller than males. This aggressive and fearless hunter's diet consists generally of birds (waterfowl), mammals (i.e. muskrats, mice, etc.), amphibians (i.e. frogs), reptiles, fish, and aquatic crustaceans. Predation of this mustelid are heavily impacted by humans but are also preyed upon by coyotes, bobcats, birds of prey and other carnivores.
"They [mink] do not hesitate to defend themselves against animals larger than themselves. Mink may be occasionally taken by birds of prey, or young in a nest may be taken by snakes, but they are agile, cryptic in coloration, and secretive in nature, thereby avoiding most predation. (Kurta, 1995)"-ADW
The Humboldt (Pacific) Marten is a subspecies of the American Marten and are an almost strictly terrestrial hunter and very elusive and veracious in their strategy. The tail of a marten is much slimmer than in the case of the Fisher but not as slim as the mink's. They are similar in size with the mink but are much lighter in coat color and a buffy-orange throat/chest patch replaces white patches as well as having triangular ear shape instead of rounded. Much like the mink, the male marten is larger than the female.
Under the untrained eye, Martens can be mistaken for the American Mink (Neovison vison) and their relative, the Fisher (Pekania pennanti ), a competitor for food and active predator of Martens. Fishers are larger and more densely covered in fur and have larger paws and claws than either the mink or marten. They are often darker as well. While both the American Mink and Pacific Marten are incredibly fearless and aggressive in their hunting, they don't compare to the Fisher. To give perspective of the sheer ruthlessness of the Fisher, they are the only successful and daring hunters of North American Porcupine (Erethizon dorsatum).
"(The fisher) is the only animal that is going to eat porcupine, it is able to go and kill it, it flips it on its back and seizes the prey by the neck" (Suffice et. al).
The Fisher has densely and wide furred tails, among other physical differences. Fishers are also opportunistic in their hunting strategies, usually consuming what ever it finds. But more often they hunt for "hare, squirrels, gallinaceous birds, small mammals, and small birds" (Suffice et. al), and berries. The same species in which martens hunt.
Some key differences between Martens and Fishers include that Fishers can hunt aquatic and semi-aquatic wildlife ( such as beavers, fish, muskrat, etc.) and drag them out of water while martens can't finesse such a feat, they are much larger and stronger- giving them the greater advantage of diversity of prey which includes terrestrial wildlife (i.e. Neovison vison, Ondatra zibethicu, Felis silvestris catus, Gallus gallus domesticus, and Vulpes vulpes ).
Attached are some comparisons of a Fisher and a Marten found within the Northern California and southern Oregon region.
Left-Right: Humboldt Marten (1st-2nd), Fisher (3rd-4th), American Mink (5th-6th)
References:
Wildlife in Managed Forests: Fisher and Humboldt Marten- https://oregonforests.org/sites/default/files/2018-12/ManagedForests_Carnivores_2018-WEB.pdf
Mammals- Humboldt Bay
https://www.fws.gov/refuge/Humboldt_Bay/wildlife_and_habitat/HumboldtMammals.html
ADW: Neovison vison; American Mink
https://animaldiversity.org/accounts/Neovison_vison/
USFWS species report on Coastal Oregon and Northern Coastal California Populations of the Pacific Marten (Martes caurina) https://www.fws.gov/oregonfwo/ExternalAffairs/News/2015/Coastal_Marten_Final_Species_Report_April_2015%20(1).pdf
Suffice, P., H. Asselin, L. Imbeau, M. Cheveau, and P. Drapeau. 2017. More fishers and fewer martens due to cumulative effects of forest management and climate change as evidenced from local knowledge. Journal of ethnobiology and ethnomedicine. BioMed Central. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5590137/
Fisher and Humboldt Marten
https://www.nps.gov/redw/learn/nature/fisher-and-humboldt-marten.htm
Slauson, K. M., G. A. Schmidt, W. J. Zielinski, P. J. Detrich, R. L. Callas, J. Thrailkill, B. Devlin-Craig, D. A. Early, K. A. Hamm, K. N. Schmidt, A. Transou, and C. J. West . 2019. A Conservation Assessment and Strategy for the Humboldt Marten in California and Oregon . United States Department of Agriculture. United States Department of Agriculture.
Kurta, A. 1995. Mammals of the Great Lakes Region. Ann Arbor, MI: The University of Michigan Press.
photo Cred: ( From left to Right)
Shem Harding, Mark Linnell/U.S. Forest Pacific Northwest Research Station and Oregon State University, Rob Chaney