The Bullock’s oriole is the widespread and common oriole of the west. Polytypic. Length 8.7".
Long wings; relatively short tail; straight, sharply pointed largely blue-gray bill with a blackish culmen; blue-gray legs. Adult Male: black eye line, crown, nape, and back. Bright orange supercilium. Bright orange on underparts and rump. Very narrow black bib. Wings black with very extensive white wing patch on coverts; flight feathers also widely fringed white. Black tail with an orange base to outer rectrices. Female: orange to orange-yellow on head and breast, showing a ghost pattern of male face pattern, with darker eye line and brighter yellowish supercilium. Back gray, below pale whitish gray with darker flanks, white or sometimes yellowish vent. Blackish wings with 2 bold white wing bars, crisp white fringes to flight feathers. Tail grayish yellow. First-fall females slightly duller, more yellowish on breast. Immature male: like female, but by spring shows black lores and bib as well as brighter orange breast. Juvenile: much duller than female, bill pink or orange-pink at base. Wings duller, brownish black with buffier and less well-developed wing bars.
The 2 subspecies are poorly differentiated and thus not field identifiable.
The orange supercilium, black eye line, and solid white wing patch are diagnostic for the adult male Bullock’s. The female and the immature can be confused with a dull Baltimore oriole. Female and immature hooded orioles are entirely yellow below, slimmer, and longer tailed and have a thin, downcurved bill. Hybrids with Baltimore orioles show features intermediate between the species.
Call: a short rattle, given by both sexes; also a sweet but faint kleek, or pheew. Song: a musical, lively series of whistles ending in a sweeter note: kip, kit-tick, kit-tick, whew, wheet. In comparison to the Baltimore oriole’s songs, the songs are shorter, not as melodic, and a lot less variable.
Status and Distribution
Common. Breeding: mainly open woodlands and riparian areas, especially fond of cottonwoods. Migration: spring arrival in south March–April, crosses into Canada by early to mid-May. Adult males southbound beginning early July, females and immatures August–mid-September. Winter: most retreat to Mexico, but a few in coastal urban habitats in southernmost California. Vagrant: casual to the east, particularly in fall and winter.
Survey data showed a gradual and slow decline between the 1960s and 1980s, particularly in the far west of the range.
—From the National Geographic book Complete Birds of North America, 2006