If the fisher delivers enough solid bites to the porcupine's face, the porcupine suffers shock or is unable to protect itself. The fisher then overturns the porcupine and begins feeding on its unquilled belly. Killing a porcupine is long, hard work and a successful kill may take over half an hour. Depending on how many scavengers share the kill, the fisher may have enough food for over two weeks. Where porcupines are common, they may make up a quarter of a fisher's diet.
Martens are generally solitary.
During early spring, litters of 1-5 sparsely furred, blind and deaf kits are born. Around 2 months of age the kits are weaned. They are able to kill prey by 3-4 months, shortly before they leave their mothers. Martens become sexually active when between one and two years old, depending on species and sex, and it is probably at this time that they try to establish territories. Evolution of the distinct species within the former two groups began during the Pleistocene only 2 million years ago.