Its large white throat patch extends onto its forelegs and underside. It is very similar to those species restricted to northern coniferous forests - the Pine marten, sable, Japanese marten and North American marten, which have smaller bibs. Two species from southern Asia, the Yellow-throated marten and Nilgiri marten, have striking yellow bibs and are again sometimes considered one species. The fisher, from coniferous and mixed woodlands of North America, is the largest species and lacks the throat patch of other martens. Martens are opportunistic hunters whose main foods are small vertebrates, especially mice, squirrels, rabbits and grouse.
Carrion is also important in their diet, as are fruits and nuts when abundant.
Martens inspect likely prey hiding places and if they sight prey, attempt a short rush to catch and kill it with a bite to the back of the neck. Fishers are typical martens in most respects. Fishers are best known for their unique technique for preying on porcupines. The arrangement of quills on a porcupine protects it from an attack to the back of the neck where most carnivores attack, but its face is not protected. Fishers stand low to the ground and can thus direct an attack to a porcupine's face, yet are big enough to inflict damaging wounds.