Bullock’s Oriole

The Bullock’s Oriole is a colourfull and characteristic bird of open woodland in western North America. It breeds from south central BC, southern Alberta and west from the prairies in the US. It winters in Mexico.

Adult Male (spring/summer)

Black crown; black eyeline; supercilium and cheek bright orange; orange from cheek extending down to belly, flanks and undertail coverts. Black throat; black nape and back. Rump and uppertail coverts are bright orange. Wing feathers black, edged white; large white patch on wing. Middle tail feather black, the rest orange and tipped black. The tail is long and the bill is thin and pointed.

Adult Female (spring/summer)

Head, uppertail coverts and tail grayish yellow. Nape and back grayish. Throat is often with some black on yellow extending to greenish gray breast and flanks. Wings gray brown with one or two indistinct wing bars.

Juvenile

Resemble adult female but the yellow is brighter and usually lacks black feathers.

General:

Medium size oriole with square tail and straight bill. Length: 17-19cm. Wing: 31cm. Weight: 36grams.

Behaviour:

Strong and direct flight, with complete wing-strokes. Makes short hops, often assisted by wings, when foraging in trees. Can hang upside down, clinging to branches for extended periods of time when foraging for insects or building nest. Often flies to ground to pick up insects. Also forages for nectar and fruit.

Habitat:

Spring and fall migration: found in variety of open woodlands and urban parklands and tall shrub land sometimes in pine, pine-oak, or fir forests. Breeding: riparian and oak, especially where trees are large and well spaced or in isolated occasionally orchard trees usually near water. Nests commonly are placed in isolated trees, at edges of woodlands, along watercourses, in shelterbelts, and in urban parks. Several active nests may be placed in close proximity.

Information:

Bullock’s Oriole was described and named by William Swainson in 1827 on the basis of material collected by William Bullock and his son, also William. In his description, Swainson wrote, “This, the most beautiful of the group yet discovered in Mexico, will record the name of those ornithologists who have thrown so much light on the birds of that country” Bullock’s Oriole is less well studied than its eastern counterpart, the Baltimore Oriole. Constructs a hanging nest of neatly woven hair (especially horse hair) fine grasses, twine and fibers lined with cottonwood or willow cotton and feathers. Clutch size is 2-7 pale blue to grayish white splotched with purple lines.

Similar species:

Conservation Status:

Widespread and common the Bullock’s Oriole’s conservation status is currently listed as Least Concern.

Capture Rates

Bullock’s Oriole breed commonly in the southern interior but rarely in the southwest coastal area of British Columbia. It is a rare visitor to Colony Farm with a few dispersing hatch year birds captured in sumer most years.

Molt Summary:

PF: HY partial-incomplete (Sep-Nov), PB: AHY complete (Aug-Oct). Occurs primarily during migration stopovers sites (esp. HYs) and/or on the winter grounds (esp. AHYs?)

Preformative molt often includes all med covs, 8 – 10 inner gr covs in ~83% of birds 1-3 terts (sometimes s6 and/or s5 and 0 (~11%) to all 12 (~46%) recs. Eccentric replacement <5% of birds with outer 3-5 pp and possibly outermost 1-2 pp covs replaced. More study needed.

PA: Absent-limited (Feb-Apr) with few SYs replacing a few head feathers.

Juveniles like this HY in August show pale grayish brown upperparts, without black and with little or no brownish streaking and pale whitish yellow throats lacking any black.

Juv male = female but may be separated by wing chord if subspecies is known.

I.b. bullockii:

Male: 95mm – 107mm
Female: 90mm – 101mm

The rectrices of the same bird are uniformly juvenal.