Williamson's Sapsucker

Williamson's Sapsucker breeds in montane coniferous forest of the western United States and adjacent Canada, and is remarkable for how differently the male and female are patterned. The male is largely glossy black with bold white markings and a yellow belly patch, while the female is barred brown and white overall with almost no black.

The contrast is so extreme that early ornithologists described the two sexes as separate species before their true relationship was understood.

• Male: mostly glossy black body with a bold white wing patch, white rump, red throat patch, and pale yellow belly
• Female: finely barred brown-and-white overall, with a brownish head and a black breast patch, lacking the male's black body
• Vs. other sapsuckers: no other Sphyrapicus species shows this degree of difference between male and female plumage
• Wing pattern: male shows a crisp white wing patch visible at rest and in flight; female shows barred wings instead

Males and females are so different in pattern that they can be mistaken for different species: males are glossy black with white markings, red throat, and yellow belly, while females are barred brown, black, and white with a brownish head. Juveniles resemble the respective adult sex pattern in muted tones. The species undergoes a single annual molt after breeding.

Breeds in montane conifer forest, especially areas with mature lodgepole pine, fir, or larch, across the western United States and southwestern Canada. It migrates to lower elevations or south into Mexico and the southwestern U.S. for winter.

Feeds heavily on sap drilled from conifer bark, along with ants gathered from tree trunks, which make up an unusually large part of its diet compared to other sapsuckers. Nests are excavated in dead or dying conifers, often in trees already affected by heart rot. Its call is a sharp, sapsucker-typical mewing note, with drumming showing the family's irregular rhythm.