55 NORTH AMEKICAN BIRDS. 



that of the Eastern species. He describes it as a curious perfijruiauce, sound- 

 ing as if two birds were singing at once and in different keys. 



IMany of this species remain in Washington Territory during the winter, 

 where Dr. Cooper met with them in December. They associated iu flocks, 

 frequented roadsides and fences, and fed upon insects and berries. 



I))-. Gambel found this species throughout the Eocky Mountains, and always 

 in company with the Sialia arctica, being by far the more aljundant species. 



Dr. Kcnnerly mentions finding this species \-ery abundant during his 

 march up the Kio Grande. Through the months of November, December, 

 and January they were always to be seen in large flocks near small streams. 



The Western Bluebird constructs a nest usually of verj' loose materials, 

 consisting chiefly of fine dry grasses. These are not woven into an elaborate 

 nest, but are simply used to line the hollows in which the eggs are deposited. 

 Near San Francisco Mr. Hepburn found a pair making iise of the nest of the 

 Hirundo imiifrons. On another occasion the Bluebirds had not only taken 

 possession of the nest of this swallow, but actually co\'ered up two fresh eggs 

 with a lining of dry grasses, and laid her o\\n aViove them. 



The eggs, usually four in number, are of uniform pale blue of a slightly 

 deeper shade tlian that of the S. sialis. They measure .87 of an inch in 

 length by .69 in breadth. 



Dr. Cooper's subsequent observations of this species in California enabled 

 him to add to his account of it in his report on the birds of that State. He 

 found it abundant in all the wooded districts, except high in the mountains, 

 and thinks they reside through tlie summer even in the liot valley of the Rio 

 Grande, where he found tliem preparing a nest in February. On the coast 

 they are numerous as far north as the 49th parallel. He found a nest under 

 the porch of a dwelling-house at Santa Barbara, showing that, like our Eastern 

 species, they only need a little encouragement to become half domesticated. 

 Tiiey raise two liroods in a season, the first being hatched early in April. 



At Santa Cruz he found them even more confiding than the Eastern species, 

 building their nests even iu the noisiest streets. One brood came every day 

 during the grape season, at about noon, to pick up grape-skins thrown out 

 by his door, and was delightfully tame, sitting fearlessly within a few feet of 

 the open window. 



In regard to their song Mr. Kidgway states that he did not hear, even 

 during the pairing season, any note approaching in sweetness, or indeed 

 similar to, the joyous spring warble which justly renders our Eastern Blue- 

 bird (S. sialis) so universal a favorite. 



The two Western species of Sialia, though associating during the winter 

 in the region along the eastern base of the Sierra Nevada, are seldom seen 

 together during the breeding-season ; the S. arctica returning to the higher 

 portions of the thinly wooded desert mountains, while the S. mexicana re- 

 mains in the lower districts, either among the cottonwoods of tlie river 

 valleys or among the pines around the foot-hills of the Sierra. 



