Fisher / Martes pennanti
Fishers are a northern Mustelid found in Vermont and are not, as the name may suggest, generally interested in catching fish. Porcupines, however, are a major prey: according to Whitaker and Hamilton (1998), fishers have been reintroduced in some areas to control increases in porcupine populations, a consequence of local extirpation of the fisher. This happened in Vermont: in the 1950s, the state sought to reintroduce fisher to “restore a balance which, since broken, has permitted abnormal development of porcupine populations” (as quoted in VT Fish and Wildlife). 124 fisher were released into 37 Vermont towns between 1959 and 1967.
Hares and rabbits are also a major component of fisher’s diet, as are mice, voles, shrews, and other small mammals.
Size: 35-54 in. L, 11 to 33 lbs.
Track Sizes: Front: 2.125-3.785 in. L x 1.375-4.25 in. W // Rear: 2-3.125 in. L x 1.5-3.5 in. W
Tips for distinguishing: Fisher tracks have some size overlap with martens and otters, but otters have larger hind feet than front feet and are more clearly webbed than fisher tracks.
Fisher feet also have more fur, which can blur foot morphology, compared to the “naked” feet of otters.
Notes: Fishers hunt in trees as well as on the ground. They can climb down trees face-first, a strategy employed to attack porcupines, who will often huddle against trees to protect the only vulnerable part of their bodies, the face.
Fishers are also territorial, with a home range varying from 2.3 to 15 square miles. They prefer forested areas, and are therefore affected by forest fragmentation.
Baseline Gait: Rotary 3/4 lope (5.75-30 in. stride length, 12-26 in. group length) or transverse 2/2 lope (deep snow) (17-45 in. stride length, 6-13 in.).
Vermont Fish and Wildlife. n.d. “Fisher.” http://www.vtfishandwildlife.com/vtcritters/animals.cfm?cat=Mammals&species=Fisher.
Whitaker, John O., and William J. Hamilton. 1998. Mammals of the Eastern United States. Third. Ithaca: Cornell University Press.