no sexual dimorphism; wingbars, spectacles (California, USA; 2011-01-02)

Plumbeous Vireo
Vireo plumbeus

Native Range: North America and Middle America

Notes: with respect to field identification, North American vireos generally can be divided into two groups: (a) those without wingbars or spectacles; and (b) those with wingbars and spectacles; this western USA species belongs to the latter group; it is closely related to the western Cassin's Vireo, which in turn is part of the broader "blue-headed group" of vireos all of which show wingbars and eye spectacles.

hooked "vireo" bill; white edgings on wings (California, USA; 2011-01-02)
grayish color overall, including on back (California, USA; 2011-01-02)
grayish color overall, white spectacles (Utah, USA; 2013-06-06)