Verdin. These little birds are a common southwestern US species, easy to find, hard to photograph. They like to forage within the foliage of small trees and large shrubs and one seldom gets an unobstructed view of them. I got lucky.
Canon 5Diii, 400 DO, ISO 400, aperture preferred setting, f6.3 @ 1/1600.
That's a very nice shot Steven.