This was the first time I have seen Brown-headed Cowbirds doing their courtship display. This was actually a group of three birds, 2 males and a female. One male put on the moves while the other watched. The male would but up its head, fluff up a bit and spread his wings and then bow to the female. While doing this the male would sign and at the end the female would give a brief closing note. Taken near Route 56, west of Worcester Airport, Worcester, Massachusetts.