Habitat Suitability Index Models: Williamson's sapsucker

The Williamson's sapsucker (Sphyrapicus thyroideus) " ... inhabits middle elevation pine forests and high elevation spruce-fir forests" (Crockett 1975:111) as well as aspen stands (Hansley 1977; Hansley, pers. comm.) throughout its range in the western Uni ted States. The Rocky Mounta in subspecies (S. t. nataliae) exhibits altitudinal and latitudinal migration with little overlap between summer and winter ranges, while the Pacific Coast subspecies (S. t. thyroideus) exhibits a primarily altitudinal migration (C roc kett 1975).