Marten hunt during both at night and day, and will rest in trees or dens. They do most of their hunting on the ground, but are agile tree climbers. Marten stay active all winter. They hunt small mammals under the snow by using natural crevices around stumps or fallen trees. When the forest is clear-cut, the snow layers change, eliminating the natural avenues to their winter food source.
Females are usually over two years old before they have their first litter.
Generally loners, they come together only briefly during the mid-summer breeding season, often mating with several partners. Birth occurs 220-276 days after fertilization. For most of that time, the egg is in a resting state, know as delayed implantation . The active pregnancy lasts only about one month. The mother's den usually consists of an underground crevice or cavity.