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.
Date: February 2008
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.
Species Profile from NatureServe
Tricolored Blackbird Agelaius tricolor
Description:A small bird (blackbird). Males are black with red, white-tipped shoulder patches (tips are buffy-white in fresh fall plumage); females are sooty-brown and streaked, with varying amounts of red on the shoulders (NGS 1983).
Life History:Nests April-June. Clutch size is 3-4. Incubation lasts about 11 days, by female (Terres 1980). Both parents feed young. Young leave nest 13 days after hatching. Two broods/year. Nests in large colonies (up to thousands of individuals). An itinerant breeder; 19 of 72 colonies (1991-1994) were active the following year (Hamilton et al. 1995). Of 75 colonies active in 1997, 19 were within 500 meters of colonies active in 1994 (Beedy and Hamilton 1997).
Habitat:
Palustrine Habitat(s): Herbaceous wetland
Terrestrial Habitat(s): Cropland/hedgerow, Grassland/herbaceous Breeding: Fresh-water marshes of cattails, tule, bulrushes and sedges (AOU 1983). Nests in vegetation of marshes or thickets, sometimes nests on the ground. Historically strongly tied to emergent marshes; in recent decades much nesting has shifted to non-native vegetation.
Nonbreeding: In migration and winter also in open cultivated lands and pastures (AOU 1983).
Distribution:
United States: CA, NV, OR
Status:
NatureServe Status: Global Status: G2G3, Global Status Last Reviewed: 03Sep2003, Global Status Last Changed: 03Sep2003, Rounded Global Status: G2 - Imperiled Other Statuses: IUCN Red List Category: EN - Endangered
