The American marten is a very charismatic creature despite its small size. The house-cat sized member of the weasel family has short legs, pointed ears and a well-furred tail that extends to about a third of its total body length. Perhaps best characterized by a pale buff or orange patch on the throat or breast, the marten is typically 21-26 inches long and weighs about 1.5 to 2.75 pounds.
Marten select for mesic closed-canopy stand types characterized by large tree diameters, plentiful coarse woody debris, snags and with a high degree of forest structure including tall trees and some degree of understory tree presence. Research has shown the marten are highly selective of habitats that have the presence of large diameter coarse woody debris on the forest floor or hollow snags that provide areas to rest between hunting bouts or to provide cover when taking a well-earned nap. In Glacier National Park, average daily movement rates for marten have been estimated to be 0.4 miles a day, ranging to 0.2-1.7 miles a day.
Anyone who has observed a weasel in the woods can easily picture these movements as a series of sprints as the marten darts in and out of downed logs or through the canopy of the trees chasing prey or avoiding predation. Marten prey on a variety of small mammals including voles, snowshoe hares, tree squirrels, flying squirrels, mice and shrews. These prey species use all the small spaces created by understory vegetation, root wads, hollow logs or other down woody debris for their own security from predators like marten or goshawk.
Based on this foraging activity, it is not surprising that the hind limbs of a marten can rotate to allow the animal to descend a tree face first. The same understory structure that marten itself use to forage for prey also provide security from hawks, owls or other animals that might predate on marten.
Based on a marten’s small home range size, dependence on small mammalian prey and avoidance of other more mobile predators, marten often avoid forest openings or young forest stands. Marten have been documented in crossing forest openings such as burns from wildfire or clearcuts, however these movements are likely not common.
At larger scales, marten presence is positively correlated with larger patches of late seral dense canopy forest. Martens appear closely associated with these interior forest conditions and tend to avoid edges where they may be at increased risk from predators. However, in southwestern Montana, it was found that marten traverse clearcuts to access mature forest. Some research has postulated that some forest openings may be beneficial to marten foraging due to increase in small mammal species produced by clearcuts. Yet the research did not conclusively document a response to increased abundance and diversity of small mammal species from regeneration harvest.
Marten are known to be sensitive to forest management. An assessment by the Forest Service in the Northern Rockies Region, evaluated ratio of existing marten habitat and compared it against the historic range of variability (HRV) to determine if there had been any substantial change from historic periods. The assessment concluded the level of existing habitat was very near the mean range of historic variability.
At a broad scale, the amount of existing marten habitat is estimated to be close to what was available during mean historic periods. However, at smaller scales, forest management for marten includes consideration of opening sizes, connectivity and maintaining a mosaic or diversity of habitat conditions that provide both present habitat suitable for marten as well as unsuitable habitats that have been put on a healthy trajectory to provide quality marten habitats in the future.
In the forests of the Northern Rocky Mountains, wildfire has been the historic disturbance agent. However, over the past century, fire suppression has altered the structure and distribution of forests in the Northern Rockies.
Research indicates that suppression of wildfire has likely resulted a larger proportion of dense forest conditions than existed when wildfire burned through forests unchallenged. With hotter summers on the horizon and additional density within forests, wildfires will likely burn at larger scales and in a more severe manner across the landscape.
On National Forest lands, managers and the public must take all these considerations into account when planning forest management projects. These considerations include best available science for not just wildlife habitat but also sound science and management from silviculture and fire management as well. Good decisions are predicated, collaborative work between the stakeholders. The Seeley-Swan has been exemplary in the collaboration interested groups, agencies and private citizens coming together to create forest management strategies that provide for viable wildlife diversity, fuels reduction for wildfire protection, forest management and restoration for healthy, sustainable forest lands.
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