By midsummer, the streaking on the upperparts of the female Redwing may be practically obliterated. Even on the underparts the whitish streaks become narrower and less conspicuous. The female Tricolor, meanwhile, becomes almost totally black, with streaking remaining only on the throat. In San Diego we can be thankful we don't have to contend with the subspecies of the Redwing in the San Francisco Bay region, mailliardorum , whose females resemble those of the Tricolor far more closely and when worn may not be distinguishable from it from gross appearance alone. Any chestnut in the plumage instantly distinguishes the Redwing from the Tricolored.
Males take two years to achieve their definitive plumage.
First-year males vary greatly in the heaviness of their streaking. Immature males acquire a plumage very like the adults' in their first fall. Entire underparts streaked, more narrowly and softly than on adult female. Entire underparts streaked, including belly, more broadly than in juvenile Redwing Flight feathers on wings narrowly edged dull brown Fortunately, at the time of year when they are most similar, the Redwings and Tricolors are nesting, and their profound differences in nesting biology readily identify them. The Redwing follows a strategy more or less traditional for a songbird, with each male advertising a territory and defending it from other males.