DWARF BROWN-HEADED COWBIRD 453 



Casual records. — Casually in northern and coastal British Co- 

 lumbia (Massett, Atlin, Calvert Islands), and northeastern Ontario 

 (Moose Factory); apparentl} 7- only casual west of the Cascades in 

 Washington (Cape Flattery), Oregon (Mercer Lake; one breeding 

 record from Medford, and California (Farallon Islands). 



MOLOTHRUS ATER OBSCURUS (Gmelin) 



Dwarf Brown-Headed Cowbird 

 HABITS 



This small cowbird is resident in Mexico and the southwestern 

 United States, north to southern Louisiana, southern Texas, south- 

 western New Mexico, southern Arizona, and southern California. 



The molts and plumages of the dwarf cowbird are like those of the 

 eastern bird, and its coloration is similar, but it is decidedly smaller. 

 It feeds on similar food. 



Bendire (1895) writes: 



It can only be considered a summer resident in southern Arizona, although 

 a few appear in winter there, as I shot an adult male on Rillito Creek, near Tucson, 

 on January 24, 1873. It usually arrives from its winter home in southern Mexico 

 about the middle of March, and is then found associating with different species 

 of Blackbirds, especially Brewer's Blackbird, frequenting the vicinity of cattle 

 ranches, roads, and cultivated fields. By April 15 the flocks have scattered, 

 and small parties of from five to twelve may now be seen in suitable localities, such 

 as the shrubbery along water courses, springs, etc , where other small birds are 

 abundant. The character of its food, and its general habits as well, are similar 

 to those of the common Cowbird, which it closely resembles, being only a trifle 

 smaller. In middle Texas the two races intergrade to some extent, and it is 

 claimed both breed there. In the lower Rio Grande Valley, Texas, the typical 

 Dwarf Cowbird is common. 



This cowbird is not supposed to breed above the Lower Austral 

 Zone, but J. Stuart Rowley tells me that he found an egg in the nest 

 of a Cassin's vireo near Lake Arrowhead in San Bernardino County, 

 Calif., at an elevation of about 5,000 feet. 



Nesting. — Friedmann (1929) lists 65 recorded hosts of the dwarf 

 cowbird, mostly small flycatchers, small sparrows, vireos, warblers 

 and other small birds, but the list includes a number of larger birds, 

 such as the Mexican ground dove, scissor-tailed flycatcher, Rio 

 Grande redwing, five orioles, two towhees, two cardinals, both races 

 of blue grosbeaks, summer and Cooper's tanagers, Western mocking- 

 bird, two thrashers, and two thrushes. Bendire (1895) says: "Ac- 

 cording to my observations, the Least Vireo seems to be oftener 

 imposed upon, in southern Arizona at least, than any other bird, the 



