CHARACTERISTICS OF TREES USED BY WHITE-HEADED WOODPECKERS FOR SAP FEEDING IN WASHINGTON

摘要

The White-headed Woodpecker (Picoides albo-larvatus) is uncommon and non-migratory throughout its geographic range in Washington, where it inhabits forests dominated by Ponder-osa Pine (Pinus ponderosa). In the northern part of their range, White-headed Woodpeckers rely on Ponderosa Pine seeds as an essential fall and winter food resource (Ligon 1973; Garret and others 1996). Previous studies investigated White-headed Woodpecker foraging in relation to food items consumed (Raphael and White 1984), tree species used for foraging (Raphael and White 1984; Morrison and others 1987), sexual differences (Koch and others 1970; Morrison and With 1987), and competition with other species (Morrison and With 1987). Although previous research revealed that White-headed Woodpeckers do feed on tree sap in California (Raphael and White 1984) and Oregon (Dixon 1995), the characteristics of trees used for sap feeding have not been described in detail. In addition, sap feeding by White-headed Woodpeckers has yet to be described in Washington. In this study, I describe the characteristics of trees used by White-headed Woodpeckers for sap feeding and comment on observations of sap feeding behavior along the east-slope of the Cascade Range, Yakima County, Washington. Information on the use of tree sap as a food resource by White-headed Woodpeckers will add to our understanding of the natural history of this species, much of which remains unknown (Garrett and others 1996).