Pacific Fisher
Martes pennanti
Historically, Pacific fisher ranged from northern British Colombia into central California through the coastal, Sierra Nevada, and Cascade ranges. Other Martes subspecies were found in the northern Rocky Mountains as well as the northeastern United States. Populations declined dramatically in the late 1800s and early 1900s in response to overharvest and habitat destruction due to logging, and fisher were extirpated in most of the United States (Powell and Zielinski 1994). Despite intensive recovery efforts including reintroductions and closed trapping seasons, fisher populations remain extremely low in Oregon, Washington, and the Northern Rockies. The Sierra Nevada fisher population is of particular concern due to ongoing fragmentation and habitat loss. In 2002 the U.S. Forest Service initiated a large-scale, long-term fisher monitoring program and in 2004 the U.S. Fish and Wildlife Service listed the Pacific fisher as warranted but precluded.
The primary difficulty associated with the conservation of forest carnivores is the lack of ecological information on their biology and habitat associations. Pacific fisher are nocturnal, naturally rare, leave little sign, utilize large ranges, and generally avoid contact with humans, characteristics that make them extremely difficult research subjects. In order to overcome these obstacles, in August 2006 the U.S. Forest Service initiated the Fisher Fuel / Wildlife Detector Dog pilot program. The program, coordinated by IWS staff and utilizing detector dogs from the University of Washington Center for Conservation Biology, is designed to collect information on pre-treatment fisher abundance in areas slated for timber thinning, and to test the efficacy of detector dogs in a hot, rugged environment.
Detector dogs, dogs trained to locate the scat (feces) of a particular species, are a recent innovation in wildlife survey techniques. Over the past ten years they have been used to successfully survey for numerous species of concern including grizzly bears, wolves, desert tortoises, black-footed ferrets, jaguars, African wild dogs, and even killer whales. Trained in a manner similar to search-and-rescue dogs, wildlife detector dogs are able to locate scats after months in the sun, under water, and even encased in ice. These scat samples in turn offer a wealth of biological information about the animal, including diet, stress levels, reproductive condition, sex, and DNA, without ever having to capture or handle the animal.
The Fisher Fuels study is designed to provide information on fisher abundance over large areas in the Sierra and Sequoia National Forests and to assist the U.S. Forest Service in determining the best method for reducing fuel loads in the region. By comparing the responses of fisher to different fuel treatment methods (mechanical thinning, prescribed burning, etc.) on small, experimental landscapes, Forest Service personnel will be better able to predict the impacts of large scale management activities.