Brown-headed Cowbird (Molothrus ater) [XC566847]
by Isain Contreras Rodr\u00edguez from Topolobampo, Ahome, Sinaloa, Mexico (alarm call)
Brown-headed Cowbird (Molothrus) [XC624558]
by Thomas Magarian from Smith Bybee Wetlands, North Portland, Multnomah County, Oregon, United States (begging call)
Subspecies
Closely related to Shiny Cowbird (Molothrus bonariensis), and much resembling it in habits, general behaviour and voice. Subspecies obscurus intergrades with artemisiae in Sierra Nevada (California).
Proposed subspecies californicus, described from L Buena Vista (Kern County), in south-central California, is subsumed in obscurus.
The following 4 subspecies are recognised:
obscurus (Gmelin, JF, 1789) - Breeds along Pacific seaboard from southern Alaska southern (east to the Cascades and Sierra Nevada) to north-western and northern Mexico (northern Baja California, also on mainland south to Oaxaca); northern populations migrate to southern parts of breeding range, in Mexico extending to southern Baja Califonia.
artemisiae Grinnell, 1909 - Breeds from western Canada (interior British Columbia east to south-central Manitoba) southern in western USA (eastern from the Cascades and Sierra Nevada) to California, Nevada and New Mexico; migrates south to Mexico (south to Michoacán).
ater (Boddaert, 1783) - Breeds from south-eastern Canada (southern Ontario east to Newfoundland) southern throughout eastern USA to central Texas, Gulf Coast and central Florida, and in eastern Mexico south to Tamaulipas. Winters in Florida and in Mexico south to Oaxaca.
californicus Dickey & van Rossem, 1922 - Southern California to northern Baja and Los Coronados Islands (off north-western Baja).
BirdLife International Species Factsheet