Nest-Site Habitat Use by White-Headed Woodpeckers in the Eastern Cascade Mountains, Washington

Abstract

The white-headed woodpecker (Picoides albolarvatus) is strongly associated with old-growth ponderosa pine (Pinus ponderosa) forest, a degraded and increasingly uncommon habitat in the Pacific Northwest. We investigated the nest-site habitat use of this species by col- lecting vegetation data at 21 known nest sites in the eastern Cascades of Washington, 12 of which we found in 1999. Sixteen of 17 (94%) nests in the ponderosa pine vegetation zone were in the 72% of the zone that occurred below 1219 m, and 15 (88%) nests were on slopes of <20% (which comprised 48% of the zone); the total area characterized by both slopes <20% and elevation below 1219 m was 181,664 ha or 33.6% of the vegetation zone. Most (16 of 21) nests were in ponderosa pines and 81% (17 of 21) were in snags. The nest snags and trees were generally large, with a mean diameter at breast height of 51.5 cm (sx = 5.13). The mean height of nest snags and trees was 12.6 m (sx = 2.33), and the mean height of the nest cavity entrance was 5.8 m (sx = 1.37). Compared to random sites located <1 km from each nest, nest sites were characterized by a greater abundance, size, and basal area of large trees and snags, primarily ponderosa pines. Management of habitat for this species should include retention of 6 to 8 large snags/0.8 ha and 8 to 10 large trees/0.8 ha in the immediate vicinity of nesting areas. Habitat requirements at the home range scale should be investigated.