Fisher (Martes pennanti)

County List:

Rule:

Forested Landscapes

Habitat Requirements may be distributed across the NEIGHBORHOOD 

      (Spruce/Fir (Pole or Sm Saw or Lg Saw or Uneven))
      or (Hemlock (Sm Saw or Lg Saw or Uneven))
      or (Mixed Upland Conifer (Pole or Sm Saw or Lg Saw or Uneven))
      or (Mixed Northern Hardwoods (Sm Saw or Lg Saw or Uneven))
      or (Mixed Upland Hardwoods (Sm Saw or Lg Saw or Uneven))
   containing:
      (Stand/Gap Openings 
      and Dead Down Woody Debris 
      and Snags 
      and Living Cavity Trees)
   neighboring:
      (Northern White Cedar (Pole or Sm Saw or Lg Saw or Uneven))
      or (Black Spruce (Pole or Sm Saw or Lg Saw or Uneven))
      or (Mixed Lowland Conifer (Pole or Sm Saw or Lg Saw or Uneven))
      or (Mixed Lowland Hardwood (Sm Saw or Lg Saw or Uneven))
      or Lowland brush 
   containing:
      (Stand/Gap Openings 
      and Dead Down Woody Debris 
      and Snags 
      and Living Cavity Trees)

Habitat List:

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Literature:

Like the marten, the fisher prefers the interior of dense coniferous forests and avoids totally open areas, but it is also capable of living in mature deciduous woods and even young, second-growth forests.

Temporary shelters include hollow logs, rock piles, and abandoned beaver lodges, but more permanent maternity dens usually are found in tree cavities. Although capable of climbing trees, a fisher primarily moves along the ground.

Prey includes snowshoe hares, red-backed voles, red squirrels, and various mice, and shrews. In addition, the fisher is the major predator of the porcupine. This mustelid occasionally preys on blue jays and ruffed grouse, and readily eats carrion. Fruits such as black cherries and blueberries form up to 20% of the summer diet.

Habitat: Extensive forests of mixed hardwoods and conifers. Found less frequently in more open stands or burned areas. Favors wetlands and mixed softwood-hardwood forest types. Diverse reports of preferred habitats.

Special Habitat Requirements: Dens in hollow trees, logs, ground holes under large boulders, or vacant porcupine dens. Rarely digs burrow. Dens may be lined with leaves and are often used as temporary shelters during winter storms; does not hibernate.

Habitat Preferences: The fisher is a forest animal with a preference for the northern coniferous, mixed conifer-hardwood, and hardwood stands which blanketed much of the Upper Great Lakes Region in presettlement days. The shaded interiors of these mature forests were slowly obliterated by the ax and plow beginning in the south and extending northward as the human population encroached on this prime fisher habitat. Unlike the marten, however, the fisher tolerates a wider choice of forested environments especially hardwoods and second-growth forests. In fact, in Maine the fisher is reported to be common today in young forest stands which have endured repeated cuttings or fires, and in replanted areas once cleared for agriculture. It would appear that if the fisher is provided with adequate protection from overharvest by fur trappers, much of northern Michigan (including parts of the northern part of the Lower Peninsula) should be suitable environment for this attractive mustelid.

Behavior: In New York, Hamilton and Cook noted that fisher will frequent upland forests in summer and use swamp areas in winter.

Fishers find sanctuary in tree cavities, hollow fallen logs, rock piles or ledges, and even brush piles. According to deVos, fishers may occupy one or more dens on a regular basis (permanent dens) while on foraging trips within their home range. Temporary dens are reported in snowbanks and deserted beaver lodges.

Key Components of Habitat: Closed canopy mature to old-growth coniferous to deciduous forest; mosaic of forest and successional habitats; suitable den sites (e.g. snags, downfall, rock crevices) in association with forest cover.

Management Actions to Enhance or Maintain Habitat Quality: Maintain high degree of interspersion between intensively managed stands and stands managed with sufficiently long rotation to provide structural and vegetative diversity similar to old growth; ensure snag availability; maintain vegetation in riparian areas and ridgelines for dispersal; maintain large debris and downfall.

Habitat: Fishers are usually found in mixed forests with a diversity of tree species and ages. Their choice of habitat is probably governed mostly by food availability, but other factors, such as large areas of continuous overhead cover and the availability of denning sites, are also important. Based on a review of the literature Allen presented a hypothetical habitat suitability index (HSI) for year-round use throughout the fisher's range. Although largely untested, optimal conditions of the model include; more than 50% closure of the tree canopy; an average dbh of overstory trees more than 10 inches; two or more stories in the tree canopy; and an overstory of more than 50% deciduous trees. In New Hampshire, Kelly suggested that by increasing the amount of habitat preferred by fishers-mixed forests with 50-75% conifers, and wetland alder-it might be possible to increase fisher densities.

Severe and extensive disturbances of the forest by logging or fire may seriously reduce its habitat value, especially during winter; this is probably because it does not provide adequate overhead cover and permits a greater accumulation of ground-level snow. Less severe disturbances may improve habitat values by increasing the density of prey and the number of den sites. In Ontario, deVos found that fishers were better able to adapt to early successional forest stages than were martens. In Maine the areas with the highest fisher densities are abandoned agricultural land that is reverting to forest. Johnson reported that fishers often used areas of interspersion (i.e. edge types) probably because prey items are more diverse, as they areas may contain species that use both types of habitat. Powell stressed that fishers select habitats with higher percentage of canopy closure. Fishers usually avoid open areas with no overhead cover, likely because of an absence of preferred prey species, a lack of overhead cover for denning, concealment, and escape, or a combination of all these factors. However, Pittaway and Johnson and Todd described fishers pursuing snowshoe hares along highways where there was no overhead cover. Leonard reported that fishers avoided open bogs in November; December, and January but they selected them frequently in February, when they were the only cover types that had a supportive crust.

In addition to maternal dens which are found most often in large deciduous trees, fishers use a variety of temporary shelters and resting sites such as hollow logs and tree cavities, brushpiles, rockpiles, burrows and dens of other animals, and snow dens. Trappers in our study reported finding fisher dens in all these places, as well as a winter den in a horizontal cleft in a rock face. Temporary dens are used for only a few days and may be near a food source. One temporary den was found inside the body cavity of a dead white-tailed deer. Fishers may den for several days during snowstorms or severe weather. R. Emery reported a fisher on his trapline that holed up for almost a week in a standing hollow tree during and following a severe snowstorm; he saw fisher tracks even though it had been several days since the last snowfall. Fisher travel is hindered by soft snow; during periods of little snow depth or of heavy crust conditions fishers travel widely, but during periods when deep soft snow is present fishers select coniferous areas where travel is easier because of its lesser snow depth.

Cover Type Analysis - Mixed hardwoods with conifer closure greater than 50% was the only cover type for which use significantly exceeded availability. Mixed hardwoods with conifer closure greater than 25% but no more than 50% indicated possible preference and open/brush areas indicated possible avoidance.

Discussion-Habitat Selection Functions: The selection function for dbh increased with dbh and exceeded 1.0 at 27 cm (10.6 in). This implies that fishers prefer habitats with trees greater than 27 cm (10.6 in) dbh. The percent canopy closure selection function increased with increasing canopy closure, exceeding 1.0 at 47%. Fishers were also found to prefer an overstory tree canopy with deciduous closure between 14 and 76%. The maximum selection value for percent overstory deciduous occurred at 33%.

Discussion - Cover Type Analysis: The conifer component of the preferred cover types consisted primarily of eastern hemlock. The mean dbh of hemlock trees within 21 fisher-used plots with conifer closure greater than 50% was 39.1 cm (15.4 in). Hemlock growing in groups or stands produces a dense canopy, providing winter shelter for a variety of wildlife. Some of the larger hemlock stands within the study area were known to be used by wintering white-tailed deer for yarding. Of the 21 fisher-used plots 32.9% had signs of white-tailed deer, 23.8% had small mammals, 19.0% had squirrels, 14.3% had snowshoe hares, and 4.8% had ruffed grouse. Porcupines are also associated with this habitat type, but were not seen in our study plots.

Abstract: Both species preferred coniferous types and avoided deciduous ones. Even though American martens and fishers overlapped in cover type preference, they did not overlap in patch size selection. American martens selected larger patch sizes of the preferred type than did fishers.

See Literature Cited section within the dissertation for specific citations.

Habitat Use - Literature Review: Fishers in Manitoba, Ontario, Michigan, New Hampshire, and Maine preferred coniferous or mixed coniferous-deciduous forest cover types. In New Hampshire, fishers avoided nonforest and deciduous cover types. Fishers in Maine foraged in dense patches of coniferous undergrowth and used deciduous stands less than expected based upon availability. In Ontario, fishers foraged along the edge of large conifer stands and in mixed stands but crossed hardwood stands without stopping. Buck et al. concluded that management practices that reduced mature conifer and increased hardwoods created poor fisher habitat in California.

Within the preferred types in Ontario, fishers used stands considered to be of late successional stage or mature age class. In Maine, fishers were associated with the pole stage or older spruce-fir type. In Idaho in summer, fishers preferred old-growth and mature forest types, avoided nonforest, pole-sapling and young forest successional stages. In winter, there appeared to be no differences between successional stages and fisher use at the stand level, but fisher locations within younger stands were associated with microsites characteristic of older forests. Fishers in California exhibited a negative response to the fragmentation of old-growth forests and Roseberg and Raphael recommended a minimum effective stand size >20 ha. Jones and Garton recommended that effective fisher habitat in Idaho was mature to old-growth forest stands ³50% of their perimeter in contact with pole-sized or older forests.

Fishers in Michigan avoided habitats with no overhead cover. In New Hampshire, fishers preferred forested stands with overstory crown closures >80%. In Idaho, fishers avoided areas with <40% canopy cover. In Manitoba, fishers avoided areas with <50% crown closure. Preferred habitat for fishers in Michigan were areas where mean dbh exceeded 27 cm, overstory canopy closure was >47%, and deciduous overstory closure was between 14-76%, (the optimum being 33%).

Within forested stands, fishers used dead down woody material, stumps, snags, and cavity trees, as foraging areas and den and rest sites. Allen cites a personal communication from Raine, who found that the majority of winter dens used by fishers in Manitoba were below the snow and associated with the roots, trunks, or branches of fallen trees. While snow tracking fishers, I found that in the course of their travels they frequently investigated downfalls, stumps, and slash piles, presumably foraging for prey.

Appendix B.

• Arthur (1987), South-central Maine
  Winter - rested in burrows and hunted in dense brushy areas. Summer - rested in the branches of coniferous trees and were active in all habitat types. Tree cavities were used as rest sites during spring and fall, and as natal dens.
• Arthur et al. (1989), South-central Maine
  Conifer stands were preferred for rest sites during spring, summer, and fall when fishers usually rested in the branches of coniferous trees. During winter fishers usually rested in ground burrows in mixed stands. Active fishers used a variety of forest types, especially during summer. During winter, fishers hunted intensively in dense patches of coniferous undergrowth, where snowshoe hare tracks were common, and used deciduous stands less than expected by availability. Deciduous stands were avoided during all seasons, coniferous stands were preferred during all seasons except summer, and mixed stands were used in proportion to their availability during all seasons. Scrub stands were avoided during winter and spring and wetlands were avoided during all seasons.
• Buck et al. (1994), Shasta-Trinity National Forest, California
  Juvenile fishers used habitat in proportion to its availability. Adult males showed no significant habitat selection but adult females did. Within lightly harvested (timber) areas, fishers appeared to use timber-type groups in proportion to their availability. Within the heavily harvested area, adult fishers, particularly adult females showed selection and avoidance. Management practices that reduced mature conifer habitat and increased the proportion of hardwoods created suboptimal fisher habitat. Fishers used riparian habitats as travel corridors.
• Clem (1977), Algonquin Region of Ontario
  Fishers were trapped on the edges of two large conifer stands and in mixed conifer-hardwoods. Fisher tracks showed that such areas were used for foraging and that pure hardwoods were crossed without stopping.
• Coulter (1966), Maine
  Fishers were associated more with the pole stage or older Spruce-fir type than any other type or size class. Fishers avoided crossing fields or frozen lakes. Fishers showed a strong tendency to remain in places where there was overhead cover. Fifty-three dens were examined some were in; snow burrows, brush piles, under logs, in hollow logs, wind throws, and tree dens.
• deVos (1951), Ontario
  Fisher movements were concentrated along creeks, lake shores, and ridges but animals also moved cross-country. Not found in recently logged or burned-over areas. Mixed or pure stands of trembling aspen and paper birch are poor habitat. Later successional stages are more suitable because of the amount of cover and the presence of denning holes in trees.
• deVos (1951), Chapleau Game Preserve, Ontario
  Fishers were more abundant in forests that were more mature, closer to the climax stage, and consisting of a high percentage or conifers.
• Jones (1991), North-central Idaho
  Mature and old-growth forests were preferred in summer, whereas young and old-growth forests were selected during winter. Fishers had a strong affinity for forested riparian habitats during summer and winter. Fishers avoided openings and forested areas with £40% canopy cover. Forested stands used by fishers in summer had more large diameter ³34.4 cm trees, snags, and logs relative to available habitat. Fishers preferred forested riparian habitats and avoided more open (£ 40% crown cover) and drier habitats, and stands dominated with pole-sized or smaller trees (£ 21.6 cm). During winter, fishers preferred decadent-seral stands of lodgepole pine and Douglas-fir having greater availability of snags, trees 21.6-34.3 cm diameter, logs >54.6 cm diameter, more understory cover of Pacific yew, and closer to water.
• Jones and Garton (1994), North-central Idaho
  In summer, fishers preferred the old-growth and mature forest types and avoided the nonforest, pole-sapling, and young forest successional stages. In winter, fishers preferred young forests and avoided nonforests and pole-sapling areas. In summer, mature and old-growth forests were used more for resting, whereas pole-sapling and younger forests were used more for hunting. In winter, no detection between successional stage by activity type was made. Even though many sites used in winter were classified as young forests, they contained several characteristics commonly associated with older forests (higher availability of large diameter trees, ³47 cm, snags >52 cm dbh, and logs, ³47 cm) relative to sites 50 m distant. Recommend that mature to old-growth stands, to be considered effective fisher habitat, should be at least 51 ha and have 50% or more of their perimeter in contact with pole-sized or older forests.
• Kelly (1977), White Mountain National Forest, New Hampshire
  Fishers selected for wetland associations (primarily alder) and mixed softwood-hardwood (51-74% softwood) forest types and against non-forested and hardwood (>74% hardwood) types. Clearcuts were selected against in winter but used in proportion to their availability in summer. Fishers avoided stands with low crown closure, particularly the most open type which had 30-50% crown closure.
• Leonard (1980), South-eastern Manitoba
  November-January, fishers usually avoided open bogs, selected against clearcuts, fields, and areas with <50% crown closure. In February, when open bog was the only cover type with a supportive crust, fishers selected it frequently. Maternal den - tree cavity in living aspen about 10 m above ground.
• Powell (1977), Ottawa National Forest, Upper Peninsula, Michigan
  Resting sites - of 31, 10 were snow dens, 9 hollow logs, 8 were holes in the ground, 2 in trees, 1 in a hollow stump. Fishers avoided habitats with no overhead cover. Fishers found in habitats utilized by porcupines (upland hardwood forest) and snowshoe hares (lowland spruce-fir, spruce-aspen, and alder stands), plus recently logged areas with many downed tree tops. Linear travel in porcupine habitat; zig-zag travel in snowshoe hare habitat.
• Raine (1981), South-eastern Manitoba
  Fishers preferred rivers, lakes, and coniferous ridges during periods of thin snow cover. During midwinter, periods of soft, thick snow cover, they preferred coniferous ridges and avoided rivers and lakes. During late winter crust periods, they showed no habitat preference.
• Thomasma et al. (1994), Ottawa National Forest, Upper Peninsula, Michigan
  Fishers preferred winter habitats with trees >27 cm dbh, canopy closure >47%, and deciduous overstory closure between 14-76% (maximum selection function at 33%). Mixed hardwoods with conifer closure >50% was the only type where used significantly exceeded availability.