Bullock’s Oriole, Icterus bullockii

Bullock’s Oriole, Icterus bullockii, Male. Photograph taken within a residential community in Alamos, Sonora, February 2018. Photograph and identification courtesy of David F Smith, Alamos, Sonora.

Bullock’s Oriole, Icterus bullockii, Female. Photograph taken within a residential community in Alamos, Sonora, March 2018. Photograph and identification courtesy of David F Smith, Alamos, Sonora.

Bullock’s Oriole, Icterus bullockii. Photograph taken within a residential community in Hereford, Arizona, April 2015. Photograph and identification courtesy of Bob Behrstock, Sierra Vista, Arizona (naturewideimages.com).

Background and Identification

Bullock’s Oriole, Icterus bullockii, is one of two subspecies of Bullock’s Oriole, both of which are found in Mexico. They are a member of the Icteridae Family of Troupials and Allies which includes Grackles, New World Blackbirds, and Orioles. This family has one hundred five individual species placed in thirty genera, and one of thirty-two global species of the Icterus Genus. They feed on arthropods supplemented by berries, fruits, and nectar, and will also frequent hummingbird feeders. Bullock’s Oriole has been poorly studied and very limited information about their behavioral patterns and biology has been documented, but they are known to live up to nine years. They are known in Mexico as Turpial de Bullock.

Bullock’s Oriole is mid-sized in stature for a member of the Icteridae family. They are a sexually dimorphic species, in both plumage and size. Mature males have bright black and orange plumage with a black eye-line and a black chin and center of the throat. Females have a gray body with a yellow head, breast, and tail. They lack black, dull greenish-gray, and yellowish underparts. Their bills are black with bluish cutting edges, their iris is dark brown, their legs and feet are gray or dull bluish gray, and their wings are gray-brown with one or two indistinct wing bars. The juvenile males resemble the adult females.

Habitat and Geographical Range

Bullock’s Oriole is found in open riparian woodlands within cottonwoods, sycamores, and willows, within native grasslands, mesquite thickets, desert scrub, and oak forests at elevations up to 3,000 m (10,000 feet). They prefer habitats with scattered trees and shrubs, particularly in areas near water.

Most populations of Bullock’s Oriole are highly migratory, overwintering in western Mexico and making stops for molting in northern Mexico in the states of Chihuahua, Coahuila, and Sonora. There are also populations with wintering grounds in southern San Luis Potosí and southern Tamaulipas on the Atlantic Slope and south to central Chiapas. The bullockii subspecies is a resident species in certain parts of its range, found year-round in Baja California, northeastern Sonora, northern and eastern Chihuahua, northern central Durango and Nuevo León.

Common Misidentifications

Bullock’s Orioles can be confused with other oriole species, particularly the Baltimore Oriole, Icterus galbula, which has a similar range and habitat preference. However, male Baltimore Orioles have a more solid black head and back, while male Bullock’s Orioles have a black cap and back with an orange face and underparts. Female Baltimore Orioles are also more uniformly yellow-brown compared to the grayish-yellow females of Bullock’s Orioles. Bullock’s Oriole and the Baltimore Oriole hybridize frequently, so much so that at one point they were considered the same species, the Northern Oriole.

Conservation Status

From a conservation perspective Bullock’s Oriole is currently considered to be of Least Concern, with stable, widely distributed populations.