Williamson's Sapsucker (Sphyrapicus) [XC104790]
by Thomas G. Graves from Upper Bighorn Creek, Conejos Co., Colorado, United States (begging call)
Williamson's Sapsucker (Sphyrapicus) [XC778443]
by Chris Parrish from Rocky Mountain National Park, CO, United States (begging call)
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.