Brewer's Blackbird

Euphagus cyanocephalus
STANFORD LOCATIONS:

Common to abundant resident in a variety of habitats virtually throughout campus.
  
Nest
Location
Nest
Type
Eggs
Mating System
Dev.
Parental Care
Primary &
2ndary Diet
Foraging
Strategy
F
I: 12-14 DAYS
ALTRICIAL
GROUND
SHRUB
 0 - 150 feet
F
4-6 (3-7)
MONOG
(POLYGYN)
F: 13-14 DAYS
MF
SEEDS
FRUIT
FOLIAGE GLEAN
 HAWKS
BREEDING: Shrubby, brushy areas (esp near water), riparian woodland, aspen parks, cultivated lands, marshes, around human habitations. 1, occ 2 broods.
DISPLAYS: Courtship (or threat between birds of same sex): male, occ female, holds bill horizontally or pointed upward, fluffs body feathers, spreads wings, tail, and vocalizes.
NEST: Variably placed; also occ in decid tree, emergent marsh veg; sturdy, of twigs, grass, matrix of mud or cow dung, lined with fine materials.
EGGS: Grayish, marked with brown. 1.0" (25 mm).
DIET: Includes few spiders, also crustaceans, snails; grass and some forb seeds. Young fed 90% insects, spiders. Occ wades to feed.
CONSERVATION: Winters s to s Mexico. Common cowbird host. Increased range and abundance with spread of agriculture; expanding eastward. Often assoc with humans, using urban, suburban, agricultural habitats.
NOTES: Nests in colonies of 3 - 100 pairs. Pairs often rejoin for up to 5 yr. Monogamous females tend to remain monogamous; secondary females of polygynous males tend to remain polygynous but change males yearly. Male occ feeds incubating female. Incubation occ starts before clutch completed, causing hatching to take up to 3 days. Large winter flocks with other blackbirds, esp Red-winged and Tricolored, but greatly outnumbered by them.
ESSAYS: Feeding Birds; Eye Color and Development; Redwing Coverable Badges; Polygyny; Coloniality; Range Expansion.
REFERENCES: Balph, 1975; Furrer, 1975; Horn, 1968; Orians, 1985.

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Except for Stanford Locations, the material in this species treatment is taken, with permission, from The Birder's Handbook (Paul Ehrlich, David Dobkin, & Darryl Wheye, Simon & Schuster, NY. 1988).