The tricolored blackbird (Agelaius tricolor) is a passerine bird of the family Icteridae. Its range is limited to the coastal areas of the Pacific coast of North America, from Northern California in the U.S. (with occasional strays into Oregon), to upper Baja California in Mexico. 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. Despite the similar names, this bird is not related to the Old World common blackbird, which is a thrush (Turdidae).