Recovery Plan for the Northern Spotted Owl - DRAFT

forested riparian habitats. Fishers in California selected coniferous forestswith a hardwood component for summer habitat (Marshall 1991).Several authors suggest that fishers select habitats with a high degree ofoverhead cover and avoid large openings (Strickland et al. 1982, Marshall1991). In Maine, where population densities are quite high in comparison topopulations in the western states, fishers are tolerant of low-density ruraldevelopment and will cross roads and farm fields to travel among forestedstands. Summer resting sites may be situated in hollow snags, under logs,brush piles, or root wads. Maternal dens usually are situated high in a hollowsnag.Fishers may use a wider variety of habitats during winter than in summer.Forest structure and prey availability are probably the critical factors in theselection of winter habitat. Jones (1991) found that old-growth stands wereimportant winter habitats for fishers in Idaho, but second-growth stands alsowere used. Fishers select stands with large remnant trees and/or logs thathave survived earlier fires in second-growth. Fishers appeared to select forestedriparian areas in winter as well as in summer. Allen (1983) concludedthat stands having a high degree of coniferous tree canopy closure providedoptimal winter habitat. Jones (1991) found no indication that snow conditionsinfluenced winter habitat use by fishers; other authors suggest that fishersmay move to lower elevations to avoid deep snow or to find prey (Marshall1991).Small to medium-sized mammals, birds, and carrion dominate the diet of thefisher; however vegetation, molluscs, and other invertebrates also have beenidentified from digestive tracts (Jones 1991, Arthur et al. 1989). Porcupinesare a major prey species wherever they occur within the range of the fisher(Strickland et al. 1982). Red-backed voles and flying squirrels are importantprey for the fisher in Idaho and Oregon (Ingram 1973). Grenfell and Fasenfest(1979) found false truffles (Rhizopogon) to be an important food of fishers innorthern California. Fishers may be common locally in parts of northernCalifornia and Maine (California Fish and Game 1986, Arthur 1987); otherwisethe species occurs at low densities.Most authors concur that mature and old-growth forests are important habitatsfor fishers. While some believe fishers require large contiguous stands ofold-growth (Marshall 1991, Washington Department Wildlife 199 lb), othersemphasize an apparent selection for habitat diversity within the home range(Strickland et al. 1982). Given the large home ranges of fishers, these twoviews may not be contradictory.Marten Martes arnericana)Distribution.-The marten (a small mammalian carnivore) inhabits the borealforests of North America from Canada and Alaska south to California, Idaho,western Montana, Colorado, Utah, and New Mexico in the west, and the GreatLakes states and northern New England in the east. Historically, the specieswas common throughout the northeastern United States and most of Canada.Loss of habitat compounded by commercial trapping resulted in the extirpationof martens from most of New England and portions of southeastern Canada bythe 1930s (Clark et al. 1987, deVos 1964).Martens have been recorded from most of the mountainous areas of Washingtonincluding the Blue, Cascade, Olympic and Selkirk Mountains, theOkanogan Highlands, the coastal ranges and Vancouver Island. Populationsare most dense in the Cascades, Selkirks, and Okanogan Highlands (WashingtonDepartment Wildlife 199 lb). All of the major mountain ranges in Oregon389