Bullock’s oriole (Icterus bullockii) is a strikingly colored songbird found in western North America. They have bright orange and black plumage and a distinct call that sounds like a rising whistle. Bullock’s orioles are medium-sized songbirds, measuring around 7-9 inches in length. They have pointed bills adapted for eating insects, fruit, and nectar.
Bullock’s orioles are migratory, breeding in western North America and wintering in Mexico. Their breeding habitat spans west from central British Columbia in Canada south through the western United States to northern Baja California in Mexico. During the winter months, they can be found in western Mexico.
Breeding Range
The breeding range of Bullock’s oriole extends across western North America. Here are some details on where they can be found during breeding season:
Canada
In Canada, Bullock’s orioles breed in southern British Columbia. Their range extends from the Cascade Mountains west to the Coast Mountains and Vancouver Island.
United States
In the United States, Bullock’s orioles breed in the following states:
– California: Throughout the state except for the southeastern deserts. Especially common along the northern coast.
– Oregon: Most of the state except for the northeastern mountains. More common in southwest Oregon.
– Washington: Breeds east of the Cascades but more common west of the mountains.
– Idaho: Southern and western regions.
– Montana: Southwestern corner.
– Wyoming: Western regions.
– Utah: Northern and central areas.
– Colorado: Western half below elevations of 8,000 feet.
– Arizona: North-central areas. Also southeastern canyons.
– New Mexico: Northern two-thirds of state.
– Texas: Mountains of western Texas.
– Oklahoma: Western panhandle.
– Nevada: Most of state except for the far southeast.
– Nebraska: Northwestern corner.
Mexico
In Mexico, Bullock’s orioles breed in northern Baja California. Their breeding range extends from the California border south to El Rosario.
Wintering Range
During the winter months, Bullock’s orioles migrate to western Mexico. Here are details on their winter range:
Mexico
Bullock’s orioles winter in the following areas:
– Along the west coast from Sonora to Guerrero. Most abundant near the Sonora/Sinaloa border.
– The Balsas River drainage of southwest Mexico.
– The Pacific slope of Chiapas.
They are rare to absent from the Yucatan Peninsula and much of northeastern Mexico.
United States
Some Bullock’s orioles overwinter in parts of the southwestern United States, though most migrate further south to Mexico. Areas where they can occasionally be found in winter include:
– Southern California: Small numbers may overwinter, mainly along the coast.
– Southern Arizona: Rare overwintering bird in lower elevations.
– Southern New Mexico: Rare wintering bird in the southwest corner.
– Southern Texas: May overwinter in Rio Grande valley but very localized.
Habitat Preferences
Bullock’s orioles utilize a variety of habitats during breeding and wintering. Here are some of their habitat preferences:
Breeding
During breeding season, Bullock’s orioles are found in:
– Riparian woodlands dominated by cottonwoods, willows, sycamores, and other deciduous trees. They nest in the canopy of these trees.
– Orchards, vineyards, and urban parks with tall trees.
– Open oak woodlands.
– Mountains up to 8,000 feet in elevation.
Wintering
In their winter range in Mexico, Bullock’s orioles inhabit:
– Tropical deciduous forests. They forage in the canopy.
– Shade coffee plantations and orchards.
– Residential areas.
– Palo verde-cactus shrublands.
Migration
During migration, Bullock’s orioles can turn up in any wooded habitat across their migratory route. They are often seen in:
– Urban parks and neighborhoods with tall trees.
– Riparian corridors.
– Oases in the desert.
Population and Conservation Status
Bullock’s oriole populations are generally stable and the species is considered of Least Concern by the IUCN Red List. Here are some key facts about their population status:
Population Estimate
– The global breeding population is estimated at around 13 million birds.
Trends
– Bullock’s oriole numbers declined between 1966-2015, according to the North American Breeding Bird Survey. The population dropped by an estimated 45% in that period.
– However, trend data from 1966-2019 shows more stable populations with no significant increase or decrease.
Threats
– Habitat loss in their breeding range due to urbanization, agricultural expansion, and river flow regulation.
– Pesticides may reduce insect food sources.
Conservation Actions
– Protecting riparian habitats in the western US through habitat conservation plans.
– Promoting shade-grown coffee in their winter range.
– Providing urban greenspaces with native trees.
Conclusion
In summary, Bullock’s orioles can be found breeding across much of western North America and wintering in western Mexico. Their distinctive orange and black plumage makes them a treat to spot during spring and summer in riparian corridors, orchards, and open woodlands throughout their range. Maintaining migratory habitats and native vegetation will be important for the continued conservation of these striking songbirds.