This cooperative effort by USDA Forest Service Research and the National Forest System assesses the state of knowledge related to the conservation status of four forest carnivores in the western United States: American marten, fisher, lynx, and wolverine. The conservation assessment reviews the biology and ecology of these species. It also discusses management considerations stemming from what is known and identifies information needed. Overall, we found huge knowledge gaps that make it difficult to evaluate the species' conservation status.
In the western United States, the forest carnivores in this assessment are limited to boreal forest ecosystems. These forests are characterized by extensive landscapes with a component of structurally complex, mesic coniferous stands that are characteristic of late stages of forest development. The center of the distrbution of this forest type, and of forest carnivores, is the vast boreal forest of Canada and Alaska. In the western conterminous 48 states, the distribution of boreal forest is less continuous and more isolated so that forest carnivores and their habitats are more fragmented at the southern limits of their ranges. Forest carnivores tend to be wilderness species, are largely intolerant of human activities, and tend to have low reproductive rates and large spatial requirements by mammalian standards.
We must have information at the stand and landscape scales if we are to develop reliable conservation strategies for forest carnivores. Ecosystem management appears likely to be central to these conservation strategies. Complex physical structure associated with mesic late successional forests will be important in forest carnivore conservation plans. Immediate conservation measures will be needed to conserve forest carnivore populations that are small and isolated. Additional forest fragmentation especially through clearcutting of contiguous forest may be detrimental to the conservation of forest carnivores, especially the fisher and marten. Specific effects will depend on the context within which management actions occur.