A male Brewer Blackbird from Golden Gate Park in San Francisco, California on "display" or "ruffed-out" common prior to copulation.
In a study examining the mating behavior of the Brewer Blackbird, researchers used stuffed specimens (dummies) of its own species to test the effects of form, posture, and color on mating responses. The reactions of females to dummies were largely negative, but males responded vigorously, often mounting the dummy and depositing semen. To obtain a mating response from the male, a dummy must meet certain requirements. Either a head or a tail must be present, but one or the other may be removed without eliminating the response. The wings were not necessary.