 This highly social and gregarious bird forms the largest colonies of any North American landbird, with a single breeding colony often consisting of tens of thousands of birds.The common name is taken from the male bird's distinctive white stripes on bottom of their red shoulder patches, or "epaulets", which are visible when the bird is flying or displaying.Despite the similar names, this bird is not related to the Old World common blackbird, which is a thrush ("Turdidae").