Martens usually den in rotten logs.
Cover requirements for American martens include dense conifer or mixed forests with 40 to 60 percent canopy closure. Open areas adjacent to these forests will be used for hunting only if they provide adequate hiding cover and food. American martens prey on small mammals, particularly mice and voles. During winter American marten need old-growth forests on mesic sites with a canopy cover exceeding 30 percent. Mature forests may support more American marten in certain areas, but diverse forest communities support more American marten over time.