Physical Characteristics: 19-26 inches long, 1 ¼-2 ¾ pounds. This long, slender-bodied weasel has relatively short limbs, a bushy tail, and silky coat ranging in color from pale yellow to dark brown with a breast spot of a varied shade. The roughly triangular head—usually lighter coloring than the body—shows a sharp nose and relatively large, rounded ears. Feet are furred and equipped with strong, non-retractable claws. Males are 15-20 percent larger than females.
Diet: The marten is an agile, opportunistic hunter, seeking prey in trees and on the ground. Voles comprise a majority of martens’ diets, but they also look for other small mammals, bird eggs and chicks, insects, carrion, squirrels, fruit, nuts, and seeds.
Habitat: The pine (or American) marten prefers mature, particularly coniferous or mixed, forests that contain numerous dead trunks, branches, and leaves to provide cover for its rodent prey. A variety of structures can be used for denning, including the branches, cavities, or broken tops of live trees, snags, stumps, log piles, rock piles, and red squirrel nests. The marten does not occupy recently burned or cut-over areas. Snow is also an important feature in many marten habitats, providing thermal protection and opportunities for foraging and resting. They are well adapted to snow and may travel extensively under the snowpack.
Range: The range of the marten coincides almost exactly with the distribution of boreal and montane coniferous forests across North America—Alaska, Canada, the Pacific Northwest, northern New England, the Rocky Mountains, Sierra Nevada, and pockets in the Midwest. It is re-establishing where mature forests have returned to areas that were formerly cut or burned. Individual territory range varies from 0.04-6.1 square miles, again coinciding with topographic and geographic features, forest cover, and the presence of other marten. The population of martens seems to fluctuate cyclically, attributed to changes in prey abundance and possibly migration. This is the smaller cousin of the Fisher. It occupies slightly higher elevations than does the Fisher. Being smaller, it is more common, though populations in the Clearwater region are not well monitored.
Reproduction: Females begin reproducing within 2-3 years, breeding in July or August and birthing a litter of 1-6 kits the following March or April. Adult marten are generally solitary outside of the breeding season and are polygamous during it. Roughly 3 months after birth, the young reach adult body weight and will disperse from their mother at varying times to establish their own home range. In the wild, marten may live up to 14 years, dependent on geographic region, exposure to trapping, and habitat quality, and are vulnerable to predatory raptors and other carnivores.
Threats: Like many unfortunate forest creatures, trapping depleted marten populations. Protection measures and reintroduction have allowed numbers to recover, but deforestation remains a serious and persistent threat to this fierce and playful creature. Trapping is still allowed in all but a few states and may account for up to 90 percent of mortality in some areas, impacting population density, sex ratios, and age structure. While not protected under the Endangered Species Act, the marten is considered a sensitive species by the Forest Service.
Miscellaneous: Pine Martens play an important role in their ecosystem: the seeds they eat as part of their varied diet are eventually dispersed throughout the forest by way of feces. In addition, their presence is often used as an indicator of environmental conditions because they are dependent on food found in mature coniferous forests, and do not reside in burned or clear-cut forest areas.