Red-winged Blackbird (Agelaius phoeniceus)
   
 
Narrative and Science Lens
  Audubon shows the easily recognized red epaulets of the male Red-winged Blackbird, which can be flashed as a signal or hidden from nearby dominant males. Brown-headed Cowbird females also recognize this species and frequently parasitize their nests. (That is, cowbirds, which don't make nests, often lay their eggs in blackbird nests.) The frequency varies, but may involve up to three-quarters of blackbird nests. Why so many? Cowbird females lay a lot of eggs--up to 36 annually. They lay them early in the day and quickly. Although Red-winged Blackbirds, especially males, protest aggressively when a cowbird approaches the nest, blackbird pairs will not eject a cowbird egg and will foster the resulting nestling. The odd egg out in this photo of a Red-winged Blackbird nest is that of a cowbird.
Courtesy Flugel (Flicker)
Why aren’t the aggressive males more effective at deterring cowbirds? Red-winged Blackbirds are polygynous (males have more than one mate) and may need to defend the nest of more than one female. They also defend against more than cowbird intruders: Up to 50 percent of Red-winged Blackbird nestings carry no genes of the territorial male.

Note that unlike the male Red-winged Blackbird Audubon portrayed, with neat yellow edging to the epaulets, those breeding here--and in much of California--show very limited, if any, yellow. These birds have been nicknamed “Bicolored Blackbirds”, a distinction from Tricolored Blackbirds, a virtually identical sister species except for conspicuous white (rather than yellow) epaulet edging.
 
  Campus Locations
Forages on lawns and occasionally on anthropogenic food waste at patios.Common breeder in the weedy vegetation on the hills near the Dish and near Lagunita, fairly rare as a breeder elsewhere on campus. A few pairs may nest in the small wetland area in the Arboretum south of Campus Drive between Lomita Drive and Palm Drive. During the nonbreeding season, small numbers (and occasionally flocks) may forage throughout campus.
  Campus sustainability
  Springtime mowing of fields, which in the Stanford area occurs for fire suppression purposes, destroys numerous Redwinged Blackbird nests. The typical lack of late-spring rain prevents the vegetation from regrowing to a height suitable for re-nesting so the birds will have lost their nesting effort for the year.
       What you can do
       1. Report any sightings—especially if you see evidence of polygmous behavior (male red-wings frequenting more than one nest; or cowbirds in redwing nests
       2. Record activity--flying, perching, feeding, being mobbing (Stanford joggers as well as crows, ravens, and hawks).
 
  Science
       Essays from The Birder’s Handbook:
            Polygyny; Red-wing Coverable Badges; Visual Displays; Communal Roosting; Sexual Selection; Cowbirds
       References:
           Orians, 1980, 1985; Ewald and Rohwer, 1982; Yasakawa, 1979.
       Videos:
  Art
       Photos:
            Johanna van de Woestijne's photo of a migratory male Red-winged Blackbird in fall plumage perched in sheep’s sorrel (Rumex acetosella)--Shoreline Park, Mountain View, CA. See more of Johanna's photographs.

       Drawings and Paintings:
            Darryl Wheye: Red-winged Blackbird and Brown-headed Cowbird, after Audubon--Too Late
 
  To add to the Science or Art links, submit bird sightings, comment on the exhibit or the web presentation, or ask questions, please use the web forms on the Art at Exits home page.