One of the most abundant birds across North America, and one of the most boldly colored, the Red-winged Blackbird is a familiar sight atop cattails, along soggy roadsides, and on telephone wires. Glossy-black males have scarlet-and-yellow shoulder patches they can puff up or hide depending on how confident they feel. Females are a subdued, streaky brown, almost like a large, dark sparrow. Their early and tumbling song are happy indications of the return of spring.
One California subspecies of the Red-winged Blackbird lacks the yellow borders to the red shoulders (epaulets) and has been dubbed the “bicolored blackbird.” Some scientists think this plumage difference may help Red-winged Blackbirds recognize each other where their range overlaps with the similar Tricolored Blackbird.
Information from the All About Birds website, , © Cornell Lab of Ornithology.