once used for nesting and feeding have been lost to urban and agricultural development. Birds adapted to nesting in agricultural fields have been disturbed by harvesting during the breeding season. Once the tricolored blackbird was placed on the BirdLife Endangered Species list, it officially became a concern both regionally and nationally. The U.S. Fish and Wildlife Service maintained the following "Primary conservation priorities for Tricolor habitat conservation and management" (The Tricolored Blackbird Working Group, 2007): Maintain, enhance, and protect existing habitat suitable for nesting, foraging, and wintering activities; Create and restore additional protected breeding habitats to support nesting and foraging; Identify mechanisms for protecting nesting and foraging habitats; To the extent allowable by law, survey private lands and identify largest and most vulnerable colonies; Encourage private landowners to protect active breeding colonies; and Encourage and enhance active breeding colonies on public lands. In 2018, the tricolored blackbird was listed as a threatened species under the California Endangered Species Act, years after petitioning by the Center for Biological Diversity. References Center for Biological Diversity - Press Release Further reading Book Beedy, E. C., and W. J. Hamilton III. 1999. Tricolored Blackbird (Agelaius tricolor). In The Birds of North America, No. 423 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA. Thesis Orians GH. Ph.D. (1961). The Ecology of Social Systems in the Red-Winged Blackbird (Agelaius phoeniceus) and the Tricolored Blackbird (Agelaius tricolor). University of California, Berkeley, United States—California. Articles (2003). Emergency protection sought for tricolored blackbird. J Wildl Rehabil. vol 26, no 3. p. 36-36. Academy of Natural Sciences of P. (1999). Tricolored blackbird: Agelaius tricolor. Birds of North America. vol 0, no 423. p. 1-23. Cook LF & Toft CA. (2005). Dynamics of extinction: population decline in the colonially nesting Tricolored Blackbird Agelaius tricolor. Bird Conservation International. vol 15, no 1. p. 73-88. Crase FT & De Haven RW. (1977). Food of Nestling Tricolored Blackbirds. Condor. vol 79, no 2. p. 265-269. Crase FT & Dehaven RW. (1976). Selected Bibliography on the Food Habits of North American Blackbirds. U S Fish & Wildlife Service Special Scientific Report Wildlife. vol 192, p. 1-20. Crase FT & Dehaven RW. (1978). Food Selection by 5 Sympatric California USA Blackbird Species. California Fish & Game. vol 64, no 4. p. 255-267. De Haven RW, Crase FT & Woronecki PP. (1975). Movements of Tricolored Blackbirds Banded in the Central Valley