Williamson's Sapsucker (Sphyrapicus) [XC370020]
by Lauren Harter from Throop Peak Trail, Angeles National Forest, Los Angeles County, California, United States (call)
Williamson's Sapsucker (Sphyrapicus thyroideus) [XC104787]
by Andrew Spencer from Upper Bighorn Creek, Conejos Co., Colorado, United States (begging call, call, call and 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.