American Marten (Martes Americana)

Threats

In the past, the cutting of vast areas of mature conifer forests destroyed much of the American marten habitat in the Sierra Nevada. While the amount of older, undisturbed forest is the Sierra Nevada is continually diminishing, the young-growth forests replacing them are not able to support viable marten populations as the original forests once did. Habitat loss and fragmentation has contributed to the decline in abundance of the marten. Zielinski et al (2005) found a simultaneous decline in the amount of old growth forests along with fragmentation of marten population in the northern Sierra since 1945. As a consequence of the habitat type marten prefer, they are often found in forests that are highly used for logging and as a result often find their habitat fragmented by these activities.

Habitat

The American marten lives in mature, dense conifer forests or mixed conifer-hardwood forests with a high percentage canopy cover and large amounts of coarse woody debris on the forest floor. These forests provide prey, protection, den sites and the large snags and downed logs utilized during rest. Furthermore, based upon the elevational ranges suitable for marten in the Sierra Nevada, the overwhelming majority of potential marten habitat in California is contained within the eleven National Forests of the Sierra Nevada. Experts in marten biology have determined that the best habitat for marten currently exists in the forests surrounding Lassen Volcanic National Park. Unfortunately, this region is also the focus of some of the most intensive clearcut logging in the state.

Conservation

The protection of large trees and closed canopy forests provides the shelter and habitat required for the survival of the American marten. The original Sierra Nevada Framework Plan ensured the protection of these critical attributes and represented the lowest possible risk to the marten by retaining these large trees and minimally required canopy cover. These provisions from the Framework were gutted however in the 2004 Framework revisions that are currently guiding Forest Service policy. The new plan allows for a significant increase in the level of fuels reduction treatments with has much lower canopy cover requirements. The 2004 revisions also set forth a plan to harvest old growth eastside pine trees, up to 30” diameter on the eastern side of the Sierra Nevada, a key structural feature for marten habitat.

Status

While the American marten is not protected under the Endangered Species Act it is considered a sensitive species by the Forest Service and is listed as a Management Indicator Species (MIS) for seven Sierra Nevada national forests including the Inyo, Lassen, Modoc, Plumas, Sierra, Stanislaus, and Tahoe National Forests. The State of California lists the American marten as a “species of special concern” and trapping the Marten is illegal in both California and Nevada.