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.
The tricolored blackbird nests in colonies, which makes it susceptible to environmental changes. It originally could be found in the marshes of California, nesting in wetland cattails and bulrushes. Scholars have noted a reduction in freshwater marshes as breeding grounds for the tricolored blackbird. Largely, this is due to human activity, and it’s estimated that between the 1930s and 1980s alone, over 95% of wetlands were disappeared. During this period, the observed tricolor population saw an 89% reduction, while the average colony size saw a 63% reduction. Altogether, the tricolor population dropped from several million to only a few hundred thousand during the twentieth century. Nevertheless, the tricolor was able to adapt in response to these severe landscape reductions. It began to use both native and non-native vegetation as well as agricultural fields as their breeding and foraging grounds. Mega-colonies of the tricolor have begun to form in the San Joaquin Valley’s numerous agricultural fields.