Type: report

Article abstract: The Tricolored blackbird (Agelaius tricolor), a near-California endemic songbird with 95% of its historic breeding range within the state, holds the distinction of forming the largest breeding colonies of any North American songbird since the extinction of the Passenger pigeon (Ectopistes migratirius). Colonies consisting of 300,000 adult birds have been reported in the past (Neff 1937). Its close relationship to the Red-winged blackbird (Agelaius phoeniceus), a solitary, territorial breeder, makes the Tricolored blackbird (or tricolor) a rare and important subject for the evolutionary study of animal social systems, a significant contributor to the phenotypic diversity of California's avifauna (Hamilton 2000, Owens and Bennett 2000), and perhaps no more, a true wildlife "spectacle" (Mittermeier et al. 2003, Hamilton and Meese 2006).