Western Bluebird

Western Bluebird is fairly common in Sonoma County year-round in appropriate habitat, but numbers increase during the winter months through breeding season. Favors oak woodlands that border grassy areas, open grasslands or other open areas with low brush. May be seen in or near lightly wooded environments near water. Also likes parks, cemeteries, farmland, orchards and vineyards--anywhere that trees and open grassy areas come together. Often perches on posts, wires, or on low natural perches before swooping down to capture insect prey, usually near the ground. May be solitary, in pairs, or in small flocks, but most often in flocks. Breeds in much of the county, except in the heavily forested northwest, which lacks the open areas this bird prefers.

The upper parts and throat of the male Western Bluebird are a pale but bright ultramarine blue. The upper breast, sides, and flanks are rust colored. The lower parts are otherwise a pale grey, although there is often a hint of blue just below the rust on the breast. The rust color extends somewhat onto the upper back in the male. Female birds are much less blue--mostly a pale, brown-tinged grey, but with a wash of rust on the breast and flanks and a paler grey throat (photo below). Folded wings are bluish, but female birds may look mostly grey, especially in the winter. Females may show a pale eyering. Juvenile birds are a brownish-grey with white spots (especially on the breast) with blue in the wings and at the rump (photo below).

If the throat is rust colored and the rust extends around the side of the neck (unlikely), you have found an Eastern Bluebird (Sialia sialis)--which would be a first for the county. You're somewhat more likely to find the all-blue Mountain Bluebird (Sialia currucoides), which, although very rare in Sonoma County, has been reported here from time to time (Bolander and Parmeter list nine county records through 2000). In October 2010, a Mountain Bluebird turned up at Point Reyes, in neighboring Marin County. In nearly all cases, however, a bluebird in Sonoma County will be a Western Bluebird.

May be confused with Lazuli Bunting (Passerina amoena), but that bird has a heavy, finch-like bill and white wing bars, lacking in the bluebird. Lazuli Bunting favors higher elevations and more heavily wooded areas than Western Bluebird and tends to stay high in trees. The blue of a Lazuli Bunting is closer to turquoise (tending toward green), whereas the blue of the Western Bluebird tends slightly toward purple.