Western USA (southern Washington, Oregon, California west of Sierra Nevada, also extreme south-western Nevada) and extreme north-western Mexico (extreme northern Baja California).
Population
Estimated population is 250,000 (2010) and decreasing.
Status EN
Habitat destruction and degradation through conversion to agriculture, combined with low reproductive success in native habitats and complete breeding failure in harvested agricultural fields, herbicide spraying and contaminated water, are the main threats.
For more information see BirdLife International Species Factsheet.
Voice
Male song is a nasal, drawn-out 'guuuaaaak' lasting 1-1.5 seconds. A nasal 'chwuk' uttered in alarm. A 'churr' uttered in flight. A range of other short, nasal call notes are heard.
Similar Species
Males differ from Red-winged Blackbird (Agelaius phoeniceus) in having deeper red epaulets with purer white borders, whereas females have darker brown and less extensively streaked plumage. Both males and females are slimmer-billed and show more square-tipped tails than Red-winged Blackbird (Agelaius phoeniceus). The breeding behaviour of the two species is very different.
References
See References.
BirdLife International Species Factsheet