California
Martes pennanti  Taken by Trail Master camera set up by Dan Weinberg (BLM), edited by Andrew Suppiger (BLM) | |
| Type of Animal: | Mammals |
|---|---|
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Mustelidae |
| Federal Status: | |
| State Status: | |
| Occurrence: | |
| Habitat: | Forest,Coniferous Forest,Deciduous Forest |
| Description: | Pacific fishers are secretive forest-dwelling mammals. They are good swimmers and climbers, often climbing high into trees to catch prey or avoid predation. Although they are primarily nocturnal, Pacific fishers may be active during the day if they are hungry or if their prey is active during the day. Their activity peaks at sunrise and sunset, and they are least active at midday. In winter, fishers are often inactive during the middle of the night. |
| Effort: | The reproductive rates of fishers is low, in comparison to other mammals. The breeding season begins in March and extends into April. Females first mate at one year of age and males first mate at two years of age. Fishers are one of the few mammals that have delayed implantation, so the young are born almost an entire year (330 to 360 days) later. One litter may consist of one to six kits, born blind and completely helpless. Male fishers do not participate in caring for the kits. At seven to eight weeks their eyes open and their teeth come in. The mothers move the kits from the natal den to the maternal den at eight to ten weeks. Mothers may use up to three different dens to raise each litter, moving the kits whenever the current den is disturbed. The young begin killing prey (without parental instruction!) at four months old (late summer to early fall), but remain within their mothers’ territories into the winter. Pacific fishers are opportunistic predators with a diverse diet. They typically eat herbivores (animals that eat plants only), but occasionally will also eat plant material and some carnivores (animals that eat meat only). Snowshoe hares are the most common prey, but fishers often eat squirrels, mice, and shrews as well. Fishers are well-known for being one of the few predators of common porcupines. They also consume various types of plants, including berries and nuts. Fishers kill small prey with the capture bite, by shaking them, or by eating them. They kill squirrels, snowshoe hares, and rabbits with a bite to the back of the neck or head. Small prey are generally consumed in one meal. Larger prey, such as deer and moose, are cached in the temporary sleeping dens. So how do they kill those prickly porcupines? Porcupines are killed with repeated attacks on the face. The porcupine rotates to keep its back to the circling fisher, sometimes putting its face against a tree or other object for protection. The fisher may climb the tree, then come down headfirst to force the porcupine away from the tree. The fisher makes the kill when the porcupine has been weakened by facial wounds. In California, Pacific fisher populations are declining rapidly, primarily due to loss of habitat. Pacific fishers are the most habitat-specific mammals in North America. They need forests with low and closed canopies to protect them from predation. Resting, foraging, and denning habitats are the most important habitat types for the Pacific fisher. Fishers use a variety of resting sites, including live trees with hollows, snags, logs, stumps, and abandoned beaver lodges. Live trees are the most common resting sites, followed by logs and snags. Most resting sites are used only once, but some resting sites may be used for several days if the weather is severe or if they have stored food at that location. For denning habitats, fishers prefer areas with very thick canopies. Pacific fishers exhibit a low incidence of diseases, parasites, and predation. Few natural causes of mortality are known. Known predators are coyotes, dogs, and large raptors. Occasionally fishers are debilitated by porcupine quills. Vehicle collisions and trapping are other causes of mortality. " |
| References: | Jameson et al. 1988. California Mammals. Wilson et al. (editors). 1999. The Smithsonian Book of North American Mammals. Whitaker (editor). 1998. National Audubon Society Field Guide to North American Mammals, Revised Edition. Zeiner et al. (editors). 1990. California’s Wildlife, Volume III, Mammals. |
| Other Sites: | "Taken by Trail Master camera set up by Dan Weinberg (BLM), edited by Andrew Suppiger (BLM)" |
| Field Office(s): | Bakersfield; Eagle Lake; Redding |