The Carlisle Mosquito Online

Friday, January 23, 2004



(Drawn by Tom Wilson)

Name: Fisher (Martes pennanti) — a member of the Mustelidae or weasel family — also sometimes referred to as a fisher cat.

When & Where Seen: Fisher tracks and scent marking found along Otter Slide Trail and Hart Land on January 6. Three separate trails — likely left by one male and two smaller females — were observed.

Description: A medium-size weasel, a fisher appears at first glance to be a cross between a bear and a house cat! The elongated body evolved to pursue prey down into tree cavities. It has a glossy brown coat which darkens to black on limbs, rear quarters, and underside. It also has white markings on chest and genital areas. Fishers have broad paws with five sharp, unsheathed claws, a triangular head with round, flattened ears, and a short muzzle with small, oval eyes that have a pale green cast. Stockier males (weighing up to a hefty 19 pounds, three feet or more in length) display a prominent sagittal crest on top of the head, and can be twice the size of slender females, which typically weigh less than 10 pounds. The long, bushy tail makes up one third of the total length.

Diet: Porcupine are a daunting prey of fisher, but locally red and gray squirrels, other small rodents, various bird species, even apples, blueberries, and beechnuts are more commonly taken. Pet rabbits, cats, and poultry are seen as prey and need to be protected from fisher. Deer carrion can feed an animal for days. Prey items are flushed out of thickets and ground cover with a determined lope. Another typical foraging tactic is to ambush squirrels at the bases of white pine. Approaching from behind the tree, the fisher will pounce around the trunk and secure its unlucky meal. Fishers store uneaten food in caches up in tree hollows, rock walls, etc.— hidden from other hungry predators. Female fishers excel at arboreal travel; males mostly forage at ground level.

Behavior: Mating occurs from March into April, following the birth of kits. Embryonic implantation is delayed up to approximately 350 days; active pregnancy lasts one to two months, and an average of three kits are born the following spring. Kits are capable of taking prey at 125 days old and separate from the mother before winter sets in. Habitat, from interior forest to suburban backyards, is used according to prey density and much territory overlap exists between ages and sexes. Central Massachusetts enjoys perhaps the highest fisher density in the country with immigrants coming from New Hampshire in the '70s. Fishers travel long circuits (up to 18.5 miles), scent marking and feeding along the way, and sleeping often in temporary dens. Much is made of the fisher's bloodcurdling scream in the dead of the night, when likely dueling raccoons are the real culprits. I've been scolded by a treed fisher before, and its call was a hoarse, rapid screech.

(Photo by Tom Wilson)

Sign: Fisher snow tracks can be found in most local wooded areas; frenzied, zig-zagging trails featuring up to three-inch print widths and trail widths to just over five inches. Fishers often use a three-four lope, also an inefficient two-two bound in deeper snow. I've encountered frequent "V-turns" — an abrupt 90-degree turn which illustrates its quick-thinking response to prey opportunities. Torn-up stumps and logs are a sign of hungry fisher. They are fond of walking the length of downed trees. Scent marking often involves straddling small saplings, leaving small urine deposits. Scat is often left among raccoon latrines at the bases of trees and rock walls. Scat is dark, twisted deposits with tapering ends comprised of bloodmeal and hair. Also look at bare tree trunks for climbing marks; scratches with approximately 1-inch spacing between claws. Last, look up into the tree canopy where fisher will often lounge the day away in squirrel nests, keenly observing us as we pass below unaware.

References: Fisher: Life History, Ecology and Behavior by Roger A. Powell; On the Fisher Trail by Eric York, Massachusetts Wildlife/Winter 1996; Wild Mammals of North America, by Joseph A. Chapman & George A. Feldhamer; Tracking & the Art of Seeing, by Paul Rezendes; Mammal Track & Sign by Mark Elbroch,

Tom Wilson is a resident of Chelmsford. He is a nature and wildlife artist and has displayed his work in the Gleason Library and at Mass. Audubon Society. He is an experienced tracker, with a special interest in the Mustelidae (weasel family), is active in several watershed organizations, and is a property steward for the Cranberry Bog in Chelmsford.

Additional fisher observations: Jean Keskulla of Concord Street has noted fisher tracks in the snow since the New Year. She found two sets of different sized tracks; perhaps the larger being those of a male and the smaller those of a female. A few years back she was lucky enough to come upon three young fishers (darker colored than the adults) which ran up into a very small pine tree and clung to branches almost too small to support their weight. She has also found scat with porcupine quills.

Habitat note: The creation of wildlife corridors and the preservation of existing ones are important to fishers which do not like to cross open land. They depend on the cover of undeveloped wooded land to connect parts of their habitat into long feeding and foraging circuits.

If fishers don't fish and herons nest in rookeries, how many nuts would a nuthatch hatch if a nuthatch would hatch nuts? Straighten out the record. Write an exposé. Send it to Kay Fairweather at 392 School St, Carlisle MA 01741 or to

2004 The Carlisle Mosquito