Williamson's Sapsucker (Sphyrapicus) [XC379157]
by Paul Driver from West Fork-Mt Baldy Trail, Apache National Forest, Apache County, Arizona, United States (begging call)
Williamson's Sapsucker (Sphyrapicus thyroideus) [XC14406]
by Richard E Webster from May Lake, Yosemite NP, California, United States (call, drumming, patterned drumming and calls)
Subspecies
Has hybridized rarely with Red-naped Sapsucker (Sphyrapicus nuchalis).
The following 2 subspecies are recognised:
thyroideus (Cassin, 1851) - Southern British Columbia south through Cascade Range and Sierra Nevada to northern Baja California (San Pedro Mártir Mts).
nataliae (Malherbe, 1854) - South-eastern British Columbia south through Rockies to Arizona and New Mexico. Winters in south of range and south to south-central Mexico.