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Brewer's Blackbird Life History


TownsBrewer’s Blackbirds live across the western half of North America, from below sea level in southern California to more than 8,000 feet in the Rocky Mountains. They occur in a huge variety of natural habitats – grasslands, marshes, meadows, woodland, coastal scrub, chaparral, and sagebrush – as well as many human-created habitats. These include lawns, golf courses, parks, city streets, agricultural fields, and power line rights-of-way.Back to top


SeedsBrewer’s Blackbirds eat mostly seeds and grains, but like many small birds they also eat lots of insects while they’re plentiful in summer – sometimes catching them in midair, or picking them off the backs of livestock. In towns, parks, and outdoor cafés, these birds will eat almost anything that’s not closely guarded. They’ve also been recorded eating small frogs, young voles, and a few kinds of nestling birds ranging from Brewer’s Sparrows to young Ring-necked Pheasants. Around marshes, you may even see them walk on lily pads to hunt aquatic insects.Back to top


Nest Placement

ShrubBrewer’s Blackbirds nest in colonies of a few to more than 100 pairs. After the first few females have chosen nest sites, others arrive and pick among nearby offerings. In some years this means you might find colonies in low shrubs; other years the same birds might nest in treetops. The birds typically nest in shrubs or trees near water, but may also nest in reeds and cattails or, occasionally, on the ground or in tree cavities.

Nest Description

Females build the nest cup from plant stems and a few twigs lined with fine dried grasses, rootlets, and hair. Sometimes they use mud or manure to cement the materials. The whole process takes 5-10 days, and the finished nest is about 6 inches across and 2 inches deep.

Nesting Facts

Clutch Size:3-7 eggs
Number of Broods:1-2 broods
Egg Length:0.9-1.1 in (2.3-2.9 cm)
Egg Width:0.7-0.8 in (1.7-2 cm)
Incubation Period:11-17 days
Nestling Period:12-16 days
Egg Description:Pale gray to greenish white, clouded or spotted with brown, pink, yellow, violet, and gray.
Condition at Hatching:Naked except for sparse gray or black down; eyes closed; weighing about an eighth of an ounce.
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Ground ForagerBrewer’s Blackbirds feed on the ground and usually in the open, but perch much higher, often on telephone or power lines. They often flock with other species, including grackles, Red-winged Blackbirds, cowbirds, and starlings. Male Brewer’s Blackbirds watch over colonies by sitting at guard perches. They meet hawks, owls, gulls, and other predators with an alarm call, diving at and sometimes striking them to make them leave. Paired birds stop associating with each other after the nesting season ends, but typically reunite the next year if both birds return after winter.Back to top


Common Bird in Steep Decline

Although they are common within their range, Brewer's Blackbirds populations declined by approximately 1.6% per year for a cumulative decline of about 57% between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 23 million and rates them 10 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Despite their overall numbers, they are listed as a Common Bird in Steep Decline for species that are still too numerous or widely distributed to warrant Watch List status but have been experiencing troubling long-term declines. Various hazards facing the species include shooting, trapping, and poisoning (measures aimed at protecting agricultural crops), as well as collisions with windows and other structures. But in general, human activities such as agriculture and settlement have created places for Brewer’s Blackbirds to live.

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Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Martin, Stephen G. (2002). Brewer's Blackbird (Euphagus cyanocephalus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Rosenberg, K. V., J. A. Kennedy, R. Dettmers, R. P. Ford, D. Reynolds, J. D. Alexander, C. J. Beardmore, P. J. Blancher, R. E. Bogart, G. S. Butcher, A. F. Camfield, A. Couturier, D. W. Demarest, W. E. Easton, J. J. Giocomo, R. H. Keller, A. E. Mini, A. O. Panjabi, D. N. Pashley, T. D. Rich, J. M. Ruth, H. Stabins, J. Stanton, and T. Will (2016). Partners in Flight Landbird Conservation Plan: 2016 Revision for Canada and Continental United States. Partners in Flight Science Committee.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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