Tag Archives: fisher

What are fisher cats, the most misleadingly-named animals out there?

One of the more obscure animals out there, fisher cats (Pekania pennanti) or ‘fishers’, in short, are predators endemic to North America. Despite the name, these animals are not cats, and they do not fish. They are, however, increasingly moving into a lot of urban and suburban areas across the USA.

Image credits of USFWS Pacific Southwest Region / Flickr.

Fisher cats are slim, short-legged mammals that resemble weasels or small wolverines. They can grow to about 145 centimeters in length (4 ft 9 in) including the tail. They’re covered in dark-brown fur, which is glossy and thick in the winter, and more mottled in the summer. They have rounded ears, and overall look quite cute and cuddly. Don’t let that fool you, however: fisher cats have vicious, retractable claws, and are quite fearsome predators for their size.

The species is endemic to various areas of North America. New England, Tennessee, the Great Lakes area, and the northern stretches of the Rocky Mountains all house populations of fisher cats. Smaller populations have also been reported in California, the southern Sierra Nevada, and the west coast of Oregon. The boreal forests of Canada also make great homes for these mammals.

The cat that’s not a cat

Taxonomically speaking, fisher cats are closely related to martens, being part of the Mustelidae family. This is the largest family in the order of Caniformia (‘dog-like’ animals) and the greater order Carnivora (meat-eaters). As such, they’re part of the most successful and rich group of predators on the planet.

Despite this taxonomic allegiance to the group Carnivora, fisher cats are omnivorous. They will happily hunt a wide range of animals of comparable size to them. They are of the very few animals that even attempt to hunt porcupines, and do so quite successfully, but prefer to hunt hares. They’re not above scouring the forest floor for plants to eat, however. They generally forage around fallen trees, looking for fruits, mushrooms, nuts, and insects. A bit surprisingly, given their name, fisher cats only very rarely eat fish.

It’s not exactly clear, then, how the animal got its name. Folklore says that fisher cats would steal the fish the early settlers used to bait traps in the Great Lakes region, but this is wholly unconfirmed. More likely, the ‘fisher’ in ‘fisher cat’ comes from ‘fisse’, the Dutch equivalent of the word ‘fitch’, from early settlers in the region. It’s also possible that it draws its roots in the French term ‘fishe’. These words refer to the European polecat or its pelt, respectively; given that fur trade was an important source of income for early settlers, it is likely that fisher cats were prized and sought-after for their pelts, and the species became associated with the polecat, who was raised for fur in Europe.

It’s easy to see why their pelts were so prized. Image via Wikimedia.

However, due to this association, fisher cats have been hunted to extinction in some parts of their natural habitat. Due to a drop in hunted pelts since the Americas were first colonized by Europeans, the animals are making a comeback and their populations are recovering and moving back into the areas they previously inhabited. Despite this, legal harvesting for fur, through trapping, is still one of the main sources of information regarding their numbers at our disposal right now.

A baby fisher cat is called a ‘kit’. Females tend to give birth to litters of one up to four kits at a time in the spring and nurture them until late summer. The kits are sightless and quite helpless at first, but become well able to take care of themselves by summertime and leave in search of their own mates.

How do they live?

Fishers spend most of their time on the ground, and have a marked preference for forested lands compared to other habitats. They’re most often found in boreal or conifer forests, but individuals have been seen in transition forests as well, such as mixed hardwood-conifer forests. They seem to avoid areas where overhead cover isn’t very thick, preferring at least 50% coverage.

Female fisher cats also make their dens in moderately large and large trees when giving birth and rearing their kits. Because of these factors, they’re most likely to be seen in old-growth forests, since heavily-logged or young forests seem not to provide the habitat that fishers like to live in.

Towards the west of the continent, where fires routinely clear forests of fallen trees (the most-liked foraging environments of the fishers), these animals tend to gravitate towards forests adjacent to bodies of water (riparian forests). They also seem to not be fond of heavily snowed areas regardless of geographical location.

Despite their habitat preferences, fisher cats have been seen encroaching ever more deeply into urban landscapes, most likely drawn by the prospect of easy food. While it is still unclear whether fisher cats hunt for pets such as household cats or small dogs, such activities would be within their abilities. Most likely, however, they search for food items discarded in trash cans.

Fisher cats stay away from humans for the most part and avoid contact. They will defend themselves if they feel cornered, however. They are quite small, so the chances of a deadly encounter with a fisher cat are slim to none, but if you ever meet one, don’t be fooled by their cuddly exterior. Give it space; their claws and fangs can be quite nasty, and there’s always the risk of infection when dealing with wounds from wildlife.

Today, these furry mammals are listed as Least Concern on IUCN Red List of Threatened Species; they are making quite a successful comeback following their historic lows. Still, habitat destruction and human encroachment remain serious issues for the species. Their ever-more-frequent sightings in cities and urban landscapes across North America are a warning sign of an issue wildlife everywhere faces: humans are taking up more space than ever, so they are coming to visit our cities, as well. Depending on what we do in the future, they may be forced to set up shop here for good.

Photo Michael K. Schwartz, U.S. Forest Service

Endangered Fishers are killed by rat poison on marijuana farms

Photo Michael K. Schwartz, U.S. Forest Service

Photo Michael K. Schwartz, U.S. Forest Service

Illegal marijuana farms often spray the vicinity of their crops with  rodenticides to exterminate pests that lurk about and compromise the plants. The farmers will most often than sprinkle the rat poison on delicious treats like peanut butter or bacon to attract the rodents and kept them away from their precious cannabis. It’s not just rats that fall for it though. Red foxes, spotted owls and, sadly, the endangered weasel-like fishers. According to a new study published in PLoS One, one in ten fishers die because of rodenticide ingestion from illegal marijuana farms.

Fishers are forest-dwelling mammals in a family that includes weasels, mink, martens, and otters. They are about the size of a large house-cat and are light brown to dark blackish-brown.

The animals can be commonly found in the Northeast and Midwest, but rare in the Northern Rockies and Northwest, where they are one of the rarest carnivores.  In 2015, the southern Sierra Nevada population was listed as threatened under the California Endangered Species Act. The fisher’s range was reduced dramatically in the 1800s and early 1900s through trapping, predator and pest control, and alterations of forested habitats brought about by logging, fire, urbanization and farming. Nowadays, you can add marijuana farming to the list .

Mourad Gabriel, who began the research as a doctoral student with the UC Davis Veterinary Genetics Laboratory and is now director of the nonprofit IERC, led the new study which investigated the effects rodenticides from marijuana farms have on fishers. He examined 167 dead fishers and found that:

  • Exposure rates to rodenticides rose from 79 percent to 85 percent.
  • Necropsies confirmed as many as six different rodenticides in one animal. Some of the chemicals found were considered safer alternatives to other commercially available rodenticides, but they nonetheless killed fishers.
  • Predation caused the majority (70 percent) of fisher deaths, but rat poisoning connected to marijuana grow sites accounted for 10 percent of fisher deaths.
  • 69 percent of all poisoning cases were in the spring, when fishers mate and raise their kits.

 Mourad Gabriel of the Integral Ecology Research Center stands amid an illegal marijuana grow site in Northern California.

Mourad Gabriel of the Integral Ecology Research Center stands amid an illegal marijuana grow site in Northern California. Photo: Mark Higley/Hoopa Valley Tribal Forestry

“We’re showing that it’s not getting better,” said Gabriel. “Fishers are the flagship species. We have to think of so many species, like Sierra Nevada red foxes, spotted owls, martens–they all are potentially at risk. This is essentially going to get worse unless we do something to rectify this threat.”

“We’re sort of a one-stop shop with a tremendous resource of people and broad array of tests that can be brought to bear about why an animal died,” said co-author Robert Poppenga, a professor and veterinary toxicologist with CAHFS. “The thing that intrigued us early on was the detection of anticoagulant rodenticides in these fishers. They’re out in the middle of nowhere. Yet, based on post-mortem testing, more than 85 percent have ARs in their system.”

Some of these poisons are particularly gruesome. Anticoagulant rodenticide, for instance, inhibit fishers’ and rats’ ability to recycle vitamin K. This causes clotting and coagulation, eventually leading to internal bleeding.