Distinguishing Features
Fishers resemble large black cats,
but are more slender, with shorter legs and a long bushy tails that
taper towards the tip. The coat is a variable grey on the head,
shoulders and upper back. The rump, tail, feet and belly are dark
chocolate brown or almost black. There may be small irregular white
spots on the chest and abdomen. Males average 3.7 kg and females
2.1 kg (Banfield, 1974).
Distribution
Columbia Basin: Throughout the Columbia
Basin in suitable habitat.
British Columbia: Fishers are found
throughout the province except for coastal islands. Believed to
be extirpated from the Lower Mainland, portions of the Thompson
and Okanagan Valleys, and the southeast corner of the province.
Global: Extensive range across northeastern
and western United States and most of northern Canada.
Habitat
Fishers use primarily coniferous
or mixed-wood habitats. Optimum Fisher habitat consists of a diversity
of forest types and, therefore, greater prey abundance. Large diameter
trees with cavities, especially riparian cottonwoods in British
Columbia, are important as natal den sites. Fishers move to larger
cavities as the young grow. Dense forest stands in the latter successional
stages provide the best quality habitat, particularly in western
North America. Weir (1995) regarded Fishers in south central British
Columbia as a habitat specialist associated with late successional
forest (Cannings et al, 1999)
Threats
Fewer than 1500 Fishers are believed
to live in province; they are vulnerable to habitat loss through
forestry, trapping and hydroelectric development. Loss of habitat
through the cutting of forests for timber or conversion to other
land uses, over-trapping and the widespread use of poisons as a
harvest and predator control method have also contributed to the
reduction and extirpation of Fisher populations. Forest harvesting
elsewhere also increases access for trappers, which is a particular
concern because Fishers are taken in Marten sets, and Marten trapping
is a mainstay of BC's fur industry (Cannings et al. 1999).
Biology
Fishers are medium sized carnivores that prey on
a wide variety of foods including birds, rabbits, porcupines and
carrion. Distribution is likely governed by the availability of
food but the presence of overhead cover may also be an important
factor (Strickland et al. 1982). Home range sizes of Fishers vary
up to 30 km2 for adult males. The range of one male will
overlap those of more than one female, but home ranges within adult
sexes are exclusive (Cannings et al. 1999).
