Bird of the Month: Brewer’s Blackbird
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
The bright yellow iris of the male Brewer’s Blackbird contrasts sharply with its glossy black plumage. The female is gray by comparison, but both sexes maintain the confident, strutting air of their walk.
Brewer’s Blackbird is a common bird of the west that is comfortable in close proximity to humans, who can be thought of as this bird’s benefactor. A range of human activities have aided the population growth and range expansion of this opportunistic bird species. Clearing land for development for housing, businesses, and roadways provides open areas which this blackbird exploits. Irrigation of crops and grain feeding of animals on feedlots provide reliable food sources for this and other blackbirds, and over the past century has allowed Brewer’s Blackbird to expand its range about 1,200 kilometers (750 miles) to the east (Martin).
This blackbird is highly social. It nests in loose colonies and in winter joins large mixed flocks with other blackbirds, cowbirds, and starlings. It has a distinctive erect walk on long legs giving it a tall appearance. It is an active bird and good examples of videos and vocalizations of Brewer’s Blackbird can be found at The Macaulay Library.
UNIQUE AMONG BLACKBIRDS
Unlike the Red-winged (Agelaius phoeniceus) and Yellow-headed Blackbirds (Xanthocephalus xanthocephalus), the Brewer’s Blackbird is not a marsh-nesting bird, although it is often associated with marshes. It prefers more open areas. Its longer legs allow for easier foraging in grass and weeds, and it is commonly found on lawns, ballfields, city parks, around human dwellings and areas frequented by humans including shores, meadows, and plowed fields (Kaufman). The length of its legs and an apparent inability to turn them to the side makes it difficult for the Brewer’s to perch on cattails and bullrushes as the other blackbirds can (Orians).
The Brewer’s may nest at the edge of a marsh, but most often the female Brewer’s builds a bulky cup nest in a tree, shrub, or on the ground. Usually, 4-6 eggs are deposited. Incubation lasts about two weeks, and the young will make first flight in another two weeks.
Brewer’s Blackbird
Scientific Name: Euphagus cyanocephalus
Length: 9”
Wingspan: 15.5”
Weight: 2.2 oz (63g)
AOU Alpha Code: BRBL
WELL-SUITED SCIENTIFIC NAME
Brewer’s Blackbird, a mostly western species, shares the genus Euphagus with Rusty Blackbird, a mostly eastern species. Euphagus, from the Greek for glutton refers to the proclivity of these two species to eat a wide variety of items in their diet (Holloway). During the breeding season the females eat more insects to promote egg development and both sexes bring insects to nestlings. Post-breeding and during winter they will add weed seeds, small fruits, grains, and waste feed in stock yards, feedlots, and farms. They prefer to forage in open areas sometimes overturning stones and waste matter to glean insects (Martin).
The species epithet cyanocephalus is from the Greek, kuanos, dark blue, and kephale, head. The breeding plumage of the male Brewer’s Blackbird is quite sleek, and it has a purplish-blue gloss to the head (Holloway). The English common name is an honorific for Thomas Mayo Brewer (1814-1880), a physician and publisher friend of John James Audubon (1785-1851), who named this and other birds for him (Martin).
STATUS AND DISTRIBUTION
Brewer’s Blackbird is considered common throughout its range. The species has a breeding range that includes the western U. S. states and Canadian provinces (Aversa, et al). Individuals that breed in the Canadian portion of the range withdraw and migrate in fall to the southern United States and northern Mexico. In Washington, Brewer’s Blackbird breeds in the lowlands and it is resident along the eastern shore of Puget Sound and in the Columbia Basin.
The Brewer’s eastward expansion as far as Illinois has brought this species into a dynamic interaction with the Common Grackle (Quicalus quiscula), which has been in a countervailing westward expansion. While separated in the past both species have previously enjoyed similar open, grassy habitats. Studies of the interactions between the species in two locations have revealed a competitive advantage for the Brewer’s Blackbird in grassy areas once populated by grackles in Ontario, and decline of Brewer’s Blackbirds in urban, suburban, and farm communities in Colorado where Common Grackles appear to have a competitive advantage (Martin).
Photo credit by Penelope Kipps. References available upon request from amccormick@eastsideaudubon.org.