HABITAT CLASSIFICATION MODELS FOR BEAVER (CASTOR CANADENSIS) IN THE STREAMS OF THE CENTRAL OREGON COAST RANGE

During 1988-1989, 22 stream habitat attributes were measured and compa red between 40 beaver-dam sites and 72 unoccupied-stream sites to iden tify attributes associated with dam-site selection by beaver (Castor c anadensis) in streams of the Drift Creek Basin, Lincoln County, Oregon . Beaver built dams in areas with wide valley-floors; narrow, low grad ient streams; high grass/ sedge cover: and low red alder (Alnus rubra) and shrub cover. Unoccupied sites lacked these characteristics. A dis criminant function model correctly classified 83% of beaver-dam sites and 88% of unoccupied-stream sites with a chance-corrected classificat ion rate of 69% (Cohen's Kappa statistic). We used 3 geomorphic attrib utes (stream width, gradient, and valley floor width) and developed a new Habitat Suitability Index (HSI) model for the basin. Land managers can use the discriminant function model or the HSI model to inventory potential beaver-dam sites along streams of the Oregon Coast Range. I nformation obtained from our habitat classification models can be inco rporated into plans to preserve unique riparian habitats maintained by beaver.