Tricolored Blackbird (Agelaius tricolor)

The Tricolored Blackbird (Agelaius tricolor) has been recognized as a focal species due to its restricted range (entire global population within North America, at least 95% of population located in California with small breeding colonies in Oregon, Washington, Nevada and Baja California), overall severe decline in population beginning before the 1930s, heightened vulnerability due to colonial nesting behavior, and losses of both nesting and foraging habitats. 
Losses of wetlands and upland habitats due to replacement of grasslands or rangeland with vineyards, orchards, and urban development are believed to be responsible for the observed declines in distribution and abundance.  The harvesting of agricultural fields in which Tricolored Blackbirds are nesting also reduces reproductive success through nest destruction.

Sources:

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.

Neff, J. 1937. Nesting distribution of the tri-colored red-wing. Condor 39: 61-81.

Tricolored Blackbird Working Group. 2007. Conservation Plan for the Tricolored Blackbird (Agelaius tricolor). Susan Kester (ed.). Sustainable Conservation. San Francisco, CA.