"The primary threat to continued population viability of martens in Idaho is habitat loss and fragmentation through harvesting of late successional forests. Marten are dependent on structural diversity associated with late successional or mature stands for denning, resting, and foraging habitat, thermal and escape cover, and gaining access to subnivean sites for resting and foraging during winter. Martens are susceptible to habitat fragmentation because of their large area requirements, specialized habitat needs, low dispersal abilities, and low biotic potential. Fragmentation of marten habitat through timber harvest activities can geographically and demographically isolate populations and lower population viability by disrupting dispersal and emigration/immigration processes." (p. 9)

"Marten home ranges are large by mammalian standards and home range size is dependent on habitat quality and forage availability (Buskirk and McDonald 1989, reviewed by Buskirk and Ruggiero 1994)" (p. 12)

"Studies show clearcuts provide poor quality habitat and support lower density populations with highter mortality rates for at least 45 years after logging. Thompson and Harestad (1994) summarized findings of 10 habitat selection studies in relation to successional stage. They found marten consistently avoided "pole" or younger seral stages, used "mature" stages either in proportion to or greater than their availability, and consistently preferred "overmature" stages. Soutiere (1979) found marten densities reduced by 66% (0.40 resident adults/ square kilometer) in fragmented landscapes composed of 50% clearcut, 25% selectively cut, and 25% uncut habitat patches, compared with unfragmented landscapes; and found little use of 0-15 year old clearcuts. Thompson (1994) reported martens in 10-40 year old clear cuts experienced high mortality rates from predation and trapping, and Thompson and Harestad (1994) concluded that marten population levels in 0-45 year old regenerating clearcuts were 0-33% of those adjacent to uncut forest." (p. 17)