MILLERS BRONZED COWBIRD 457 



Food. — The same authors found milo maize or Egyptian corn in 

 two stomachs examined, miscellaneous seeds in nine and a caterpillar 

 in one. Gilman (1914) says that they "stay around the barnyard 

 where they pick up corn and other grains and scraps from the table 

 thrown to the chickens; and they also remain around the school yard, 

 where they eat watermelon set in the shade for birds of all kinds." 



Behavior. — On this subject Dickey and van Rossem (1938) write: 



Except during the breeding season, red-eyed cowbirds normally wander in large 

 flocks. Occasionally they consort with the grackles, but as a rule each species is 

 likely to keep pretty well to itself. The largest cowbird assemblages noted were a 

 flock estimated at between 400 and 500, which was seen in some bare trees along 

 the road near Santa Rosa on October 24, 1925, and another of about 100 which 

 was beach-combing through the litter of the high-tide mark at Barra de Santiago 

 on April 1, 1927. Groups of less than 50 were decidedly more numerous, and the 

 average fall, winter, and early spring flocks contained 25 or 30 birds each. 



The great disparity in the relative numbers of males and females is noticeable 

 even in the winter flocks, but becomes still more apparent when the spring break- 

 up occurs. About April 1 or even a little earlier, the flocks disintegrate into little 

 bands consisting almost invariably of a single old male and his harem of four or 

 five females. This small group retains its identity as a unit until the following fall. 

 The male is in constant attendance, strutting with shoulder tufts raised and chest 

 puffed out before first one and then another of his flock, who for the most part 

 ignore him completely. 



In southern Arizona, Harry S. Swarth (1929) observed: "Bands of 

 six or eight attended individual horses or steers, often in company 

 with Dwarf Cowbirds, trotting closely alongside the selected animal in 

 order to take advantage of the small patch of shade it afforded, and 

 showing a marked preference for feeding by the animal's head." 



DISTRIBUTION 



Range. — Central Arizona to western Mexico. 



Breeding range. — The bronzed cowbird breeds from central and 

 southeastern Arizona (Wickenburg, Phoenix) and southwestern New 

 Mexico (Guadalupe Canyon), south through central Sonora (Opodepe, 

 Guaymas), western Chihuahya (Durazno), and Sinaloa (Labrados, 

 Presidio) to Nayarit (Tepic) and Colima. 



Winter range. — Winters throughout most of its breeding range 

 north rarely to southern Arizona (Tucson). 



Casual records. — Accidental in southeastern California (Havasu 

 Lake) . 



Migration. — The data deal with the species as a whole. Early 

 dates of spring arrival are: Veracruz — southern Veracruz, April 12. 

 Texas — Mission, April 17. Arizona — Tucson, April 11 (median of 4 

 years, April 23). 



Late date of spring departure: Sonora — Rancho La Arizona, 

 May 7. 



