78 U.S. NATIONAL MUSEUM BULLETIN 23 7 paut i 



"Pieces of shed snakeskin are said to be a quite common feature of 

 this grosbeak's nests. No such material appeared in the present 

 nests, despite the fact that bull snakes (Pituophis catenifer sayi), 

 garter snakes (Thamnophis elegans vagrans and T. radix haydeni), 

 and prairie rattlesnakes (Crofalus v. viridis) frequent the area. 



Nesting. — The nesting habits of the western blue grosbeak are evi- 

 dently very similar to those of its eastern relative. Airs. Bailey (1928) 

 says that, in New Mexico, the nest is placed in "tall weeds, vines, 

 bushes, willows, and fruit trees" and is "made of grasses and rootlets." 

 She says further: "In twenty-three nests located during a period of 

 five years, twenty-one had snake skin, as a foundation." 



Eggs. — The three or four eggs laid by this grosbeak are indis- 

 tinguishable from those of the eastern race. Measurements of 40 

 eggs average 21.8 by 16.3 millimeters; the eggs showing the four 

 extremes measure 23.9 by 16.8, 21.8 by 17.8, 20.3 by 15.8, and 20.8 by 

 15.5 millimeters. 



The molts and plumages, food, voice, and the habits in general of 

 the western blue grosbeak are similar to those of the eastern bird. 



Distribution 



Range. — Southeastern California, southern Nevada, Colorado, and 

 South Dakota to Costa Rica. 



Breeding range. — The western blue grosbeak breeds from south- 

 eastern California (Coachella, Needles) , southern Nevada (Pahranagat 

 Valley), southern and eastern Utah (Santa Clara River, Boulder, 

 Vernal), central and northeastern Colorado (Sedalia and Yuma 

 County), northwestern and central South Dakota (Belle Fourche, 

 casually, Badlands National Monument, and Pierre), and eastern 

 Nebraska (Lincoln) south to northeastern Baja California (Cerro 

 Prieto), northwestern Durango (Rancho Baillon), southern Coahuila 

 (Hip61ito), and west central Texas (San Antonio, Hidalgo); east 

 to western Kansas and central Oklahoma (Minco, Woods County). 



Winter range. — Winters from southern Sonora (Guirocoba, one 

 record) and Sinaloa south along the Pacific coast of Mexico and 

 Central America. 



Casual record. — Casual in eastern Washington (Spokane) . 



Egg dates. — Arizona: 14 records, June 14 to August 21; 7 records, 

 July 17 to July 27. 



Texas: 20 records, May 15 to July 3; 12 records, May 29 to June 8. 



