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Bullock's Oriole

Icterus bullockii ORDER: PASSERIFORMES FAMILY: ICTERIDAE

IUCN Conservation Status: Least Concern

Nimble canopy-gleaners of open woodlands in the western U.S., Bullock's Orioles dangle upside down from branches while foraging and weaving their remarkable hanging nests. Adult males are flame-orange with a neat line through the eye and a white wing patch; females are washed in gray and orange. In addition to insects, they eat fruit and nectar—a trait some bird watchers capitalize on by offering nectar, jelly, and orange halves in summer backyards. Listen for their whistling, chuckling song in tall trees along rivers and streams.

At a GlanceHelp

Measurements
Both Sexes
Length
6.7–7.5 in
17–19 cm
Wingspan
12.2 in
31 cm
Weight
1–1.5 oz
29–43 g
Relative Size
Larger than a Yellow Warbler; about the same size but slimmer than a Brewer's Blackbird.
Other Names
  • Northern Oriole (in part)
  • Oriole de Bullock, Oriole à ailes blanches (French)
  • Bolsero calandria (Spanish)

Cool Facts

  • Bullock's Orioles often take nectar from flowers, and they will sometimes raid hummingbird feeders for their sugar water.
  • Both male and female Bullock's Orioles sing—the male more sweetly, the female often more prolifically.
  • In the Great Plains, where their ranges overlap, Bullock's and Baltimore Orioles frequently hybridize. The two species were lumped together for a while as the Northern Oriole. Genetic research has since determined, however, that they are not very closely related.
  • The Bullock's Oriole was described and named by William Swainson in 1827, drawing on material collected by English father-and-son naturalists William and William Bullock in Mexico.
  • Bullock's Oriole pairs may nest outside the territory where the male advertises.
  • The oldest recorded Bullock's Oriole was a male, and at least 8 years, 11 months old, when he was recaptured and rereleased during banding operations in Colorado in May, 2007.

Habitat


Open Woodland

Bullock's Orioles breed in riparian and open woodlands, including urban parks. They favor areas where the trees are large and spaced well apart or in isolated clumps. They often nest in sycamores, cottonwoods, willows, deciduous oaks, madrones, and large mesquite trees. Live oaks, pecans, orchard trees, saltcedar and occasionally conifers are also used. This bird gravitates toward larger trees than those used by the Orchard Oriole. They use similar open woodland habitats during migration and winter, and may also be found in pine, pine-oak, or fir forests.

Food


Insects

Bullock's Orioles eat insects and other arthropods, as well as fruit and nectar. They glean insects from leaves, branches and trunks; they also pluck insects from spiderwebs or from the air, and take ripe fruit from bushes and trees. Bullock's Orioles use a method called "gaping" to extract juice from fruit, and also sometimes from tough-skinned caterpillars. Thrusting their closed bills through the skin and into the flesh of the fruit or animal, they then pry their bills open inside and lap up the pooling juices with their brushy tongues. Sometimes these orioles skin caterpillar prey by hitting it repeatedly on a branch. Before eating honeybees, they extract and drop the stinger. Common prey insects include caterpillars, grasshoppers, and crickets. The birds also take beetles, ants, bugs, scale insects, stinkbugs, leafhoppers, treehoppers, and small spiders. Rarely, they eat small lizards. They take nectar from agaves, introduced eucalyptus, and other flowers. Commonly consumed fruits include blackberries, raspberries, cherries, and figs. Nestlings are fed crickets, stick insects, camel crickets, cicadas, moth and butterfly pupae, earwigs, ants, and crane flies.

Nesting

Nesting Facts
Clutch Size
3–7 eggs
Number of Broods
1 broods
Egg Length
0.8–1.1 in
2–2.8 cm
Egg Width
0.6–0.7 in
1.4–1.8 cm
Incubation Period
11 days
Nestling Period
14 days
Egg Description
Pale bluish or grayish white, splotched with purplish brown lines.
Condition at Hatching
Helpless with long, sparse white down.
Nest Description

The female usually weaves the nest, but the male may assist, with one partner working on the inside and other outside, bringing nest material. The project can take up to 15 days to complete. The nest is gourd-shaped and neatly woven from fibers such as hair, twine, grasses, or wool. It's lined with soft materials such as feathers or the "cotton" from cottonwoods or willows. Nest depth varies, averaging a bit less than 4 inches and ranging up to 15 inches. On average, Bullock's Oriole nests are deeper and wider than those of the Baltimore Oriole, though the opening diameter is smaller.

Nest Placement

Tree

The female selects the nest site, typically 10 to 25 feet above the ground in an isolated tree or at the edge of a woodland, commonly near water. The nest is usually suspended from the ends of flexible branches to discourage predators. It is not necessarily situated within the male's advertising territory. Several other active nests may be close by.

Behavior


Foliage Gleaner

Bullock's Orioles glean and probe in trees for insects and nectar, often hanging upside down for extended periods. They make short hops from branch to branch, sometimes flying to the ground to nab insects. Their flight is strong and direct. During migration, they congregate in small, loose, mixed-gender flocks. The male performs a bowing courtship display, hopping from branch to branch and bowing to the female every second or so—all the while singing loudly and exposing his colorful plumage. During nest-building and border disputes, the female may display with quivering wings, holding her body in a roughly horizontal position. Rival males face off at territorial borders and chase each other through tree branches. Bullock's Orioles remain paired up throughout the breeding season but may take new mates in later years. Both members of a pair guard the nest and may mob squirrels, crows, jays, and other predators. Females tend to sing near the nest site, while males often sing elsewhere.

Conservation

status via IUCN

Least Concern

Bullock's Oriole are widespread and common, but populations declined by 29% between 1966 and 2014, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 7 million with 86% spending some part of the year in the U.S., 96% in Mexico, and 3% breeding in Canada. They rate an 11 out of 20 on the Continental Concern Score and are not on the 2014 State of the Birds Watch List. This oriole is locally affected by habitat loss, and possibly by pesticide use.

Credits

Range Map Help

Bullock
View dynamic map of eBird sightings

Migration

Medium-distance migrant. Most winter in western Mexico; a few individuals may be resident in coastal southern California.

Backyard Tips

Bullock's Orioles don't eat from seed feeders, but they do look for sugary foods as they complete their spring migration. A half-and-half mixture of water and grape jelly, blended into a syrupy nectar and set out in a small, shallow container, may attract the birds to your backyard as breeding season begins. They may also visit hummingbird feeders, as long as they provide perches. Birding stores sell oriole feeders that are specifically designed to attract orioles with sugar water. You can also put out orange halves in a shallow dish of water (to discourage ants). Replace the fruit daily to prevent drying or growth of harmful mold. Start putting out food before migrants arrive in your area; if it's not there when they first canvas your yard, they'll keep going. Once the birds have begun nesting, transition from sweets to mealworms. Visit Project FeederWatch for more information on how, what, and where to feed birds in your backyard.

Find This Bird

In the generally arid West, riparian (or streamside) woodlands hold a lot of the songbirds, including Bullock's Orioles. Look for them in cottonwood trees where they forage in the outer branches or build their intricately woven, hanging nests. Orioles are vocal birds; listen for their sweetly whistled notes interspersed with harsh chattering, sung by both males and females. Sometimes they give just the chattering notes as they take flight, and this can help you locate them, too.

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