WatchList Species Account for Williamson’s Sapsucker (Sphyrapicus thyroideus)

Qualifies for the list as a Declining Yellow List Species


Photo: Peter LaTourrette/
Photo: Peter LaTourrette/

This strikingly sexually dimorphic woodpecker breeds discontinuously in the Pacific Northwest, Northern and Southern Rocky Mountains, and California and the Great Basin, with a disjunct and very range-limited population in Baja California Norte.


Some populations are resident, while others winter in the more southerly portions of the breeding range through the mountains of Mexico to Jalisco; females move farther to the south than do males.


It breeds in coniferous and mixed deciduous-coniferous forest at middle to high elevations, feeding on conifer sap and phloem during its pre-nesting period and nonbreeding seasons. When feeding young, this sapsucker switches to ants, an important source of protein for the nestlings. Fruits provide a substantial resource during the winter.


Breeding Bird Survey information from the 1990s indicates a decreasing population trend for this species. To maintain a maximum population in an area, a high number of snags, estimated at 371 per 247 acres in one study in the Pacific Northwest, is needed. Forest management plans should place emphasis on conserving groups of large snags. Fires in mixed conifer forest that creates snags may lead to higher breeding densities.