NORTH AMERICAN BIRDS. 273 



is sparsely spotted. Ten specimens selected at random from a very 

 large series exhibit the following sizes: .8ox.62, .82X.66, .84X.62, 

 .88x.66, .89X.63, .87X.65, .82x.6o, .83X.64, .89X.64, . Sox. 62. A 

 common size is .88 x .64. 



4950. Molothrus ater obscurus (GMEL.) [2580.] 



Dwarf CowMrd. 



Hab. Mexico, and southern border of the United States from Texas to Arizona and Lower California. 



This is a smaller form, inhabiting the southern border of the 

 United States from Texas to Arizona and southward. Its habits are 

 identical with the Cowbird of the East, and the eggs are colored the 

 same, but like the bird, average smaller. Five specimens measure : 

 .77 x .60, .80 x .59, .75 x .59, .70 x .57, .72 x .58. The average size of ten 

 specimens from Arizona is .74x .59. 



496. Callothrus robustus (CAB.) [259.] 



Red-eyed Cowbird.* 



Hab. Eastern and Southern Mexico, Yucatan, and south to Panama; north to the lower Rio Grande 

 Valley in Texas. 



A bronze-colored Blackbird with blood-red iris. Common on the 

 Lower Rio Grande in Texas. Dr. Merrill took specimens at Hidalgo, 

 but they were not so abundant at this point as lower down the river, 

 where they are common throughout the year, a small proportion going 

 south in winter. Those that remain gather in flocks with the Long- 

 tailed Grackles, common Cowbirds, Brewer's, Red-winged and Yellow- 

 headed Blackbirds. 



He found its eggs in the nests of Bullock's, Hooded and the 

 Orchard Orioles, once in the nest of the Yellow-breasted Chat, and 

 Red-winged Blackbird, Scissor-tailed Flycatcher and Texan Cardinal 

 (Pyrrhuloxia sinuata}. The eggs of the Red-eyed Cowbird are plain 

 bluish-green, similar to that in the eggs of the Blue Grosbeak. Dr. 

 Merrill gives the average size of twenty eggs as .90 x .70, the extremes 

 being .95 x .75 and .82 x .65. 



497. Xanthocephalus xanthocephalus (BONP.) [260.] 



Yellow-headed Blackbird. 



Hab. Western North America to the Pacific, east regularly to Wisconsin, Illinois, Kansas and 

 Texas. Accidental in the Atlantic States. 



The handsome Yellow-headed Blackbird is found generally dis- 

 tributed on the prairies in all favorable localities from Texas on the 

 south to Illinois and Wisconsin, thence to the Pacific. A common bird 

 in the West, nesting in May and June. It collects in colonies to breed 

 in marshy places anywhere in its general range, often in company with 

 the Red- winged Blackbird. The nests are usually placed in the midst 



* No. 496 in the A. O. U. Check List is Molothrus ceneus (Wagl.), Bronzed Cowbird. These names are 

 now applied to the western form of this bird from Western Mexico, etc. 



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