Plumage and behavior differ greatly between interior and coastal populations. Coastal populations of the western scrub-jays are confiding, tame, and easily seen. Interior populations are more secretive and often are seen darting from bush to bush or are simply heard giving their harsh calls. Pairs of all North American subspecies hold territories year-round. Polytypic. Length 11".
This is a long-tailed jay with a small bill and no crest. Adult: generally bluish above, gray below with a contrastingly paler throat and upper breast, and a variable bluish band on the chest. Juvenile: much grayer overall, showing very little blue on the head. Flight: Usually undulating with quick deep wingbeats.
The subspecies of western scrub-jays form 3 well-defined subspecies groups that may represent separate species: the coastal californica group; the interior woodhouseii group; and the sumichrasti group confined to southern Mexico. Subspecies groups occurring north of Mexico are discussed below. Formerly grouped with Florida and island scrub-jays and considered one species, the scrub-jay.
Call: gives a variety of harsh calls, most frequently a raspy shreeep, often repeated in a short series of shorter notes: shuenk shuenk shuenk shuenk. Interior vocalizations are rougher and lower pitched.
Status and Distribution
Common. Breeding: scrubby and brushy habitats, particularly with oak, pinyon, and juniper; also found in gardens, orchards, and riparian woodlands. Dispersal: largely resident, but prone to occasional irruptions, particularly members of the woodhouseii group. Irruptions often coincide with movements of pinyon jay, Steller’s jay, and Clark’s nutcracker. Vagrant: casual to southwestern British Columbia, eastern Washington, southeastern California, central Kansas. Accidental to southern Manitoba, northeastern Illinois, and northwestern Indiana.
Breeding Bird Survey and Christmas Bird Count data indicate a gradual increase in populations north of Mexico.
—From the National Geographic book Complete Birds of North America, 2006