Brown Headed Cowbirds are a little bit smaller than Cardinals and except mating season they form flocks. These pictures were taken early March of this year and they were still forming a flock when they came to my bird feed stand. They are a little bit noisy and act as if the feed stand is their own property so other birds such as house finches, chickadees, cardinals and even Eurasian Doves tend to avoid joining them. So when these Brown Headed Cowbirds come to my feed stand, no other birds can be seen around there.
The birds on first and second photos are all male Brown Headed Cowbirds and the right side bird of third picture is female Brown Headed Cowbird.