THE DEMISE OF "CALIFORNIA'S" BLACKBIRDS: AN HISTORICAL PERSPECTIVE.
Edward C. Beedy; Beedy Environmental Consulting; 12213 Half Moon Way, Nevada City, CA, 95959; (530) 274-7232; tbeedy@comcast.net;
The tricolored blackbird (Agelaius tricolor) is a near-endemic California passerine that now forms the largest breeding colonies of any North American land bird, after the extinction of passenger pigeon (Ectopistes migratorius) in 1914. Unlike their close relative, the widespread and territorial red-winged blackbird (Agelaius phoeniceus), the tricolored blackbird has a very limited geographic range and is nearly restricted to California - more than 99% of the global population occurs within the state. The number of tricolored blackbirds plummeted during the 20th Century due to a variety of factors including on-going habitat losses through widespread conversion of natural habitats to agriculture and urbanization, pesticide applications resulting in insufficient insect resources, and chronic destruction of breeding colonies by the harvest of their nesting substrates. The conservation of the tricolored blackbird is a matter of increasing concern owing to population declines, and because the species' habit of nesting in large colonies make it more vulnerable to nesting failures that can affect thousands of nests at a single colony. Due to this dramatic decline across the species' range, the California Fish and Game Commission made a final determination to list the tricolored blackbird as Threatened under the California Endangered Species Act in April 2018.
The Anthropocene: Decline & Extinction I