THE BIRD BOOK 



766. Bluebird. Sialia sialis sialis. 



Range. — Eastern United States, breeding from the Gulf to southern Canada. 

 Winters in the southern half of the United States. 



These familiar birds build in cavities in trees, 

 usually below 20 feet from the ground, crev- 

 ices among ledges, bird boxes and in any suit- 

 able nook they may discover about buildings, 

 providing that English Sparrows do not molest 



them. They raise several 



broods a year, commencing in 



April when they lay from 



three to six pale bluish white 



eggs (rarely pure white) ; 



size .80 x .60. The cavities 



Of their nesting sites are lined 

 Bluish white with g rasses and feathers 



usually, although I have found the eggs on 

 the unlined bottom of cavities in trees. 



Sialia sialis 



766a. Azure Bluebird. 

 fulva. 



Range. — This pale variety is found in south- 

 ern Arizona and southward. 



Its nesting habits are the same and the eggs 

 are indistinguishable from the last. 



767. Western Bluebird. Sialia mexicana occidentals . 



Range. — Pacific coast from Lower California to British Columbia. 



The Western Bluebird is as common and familiar in its range as the common 

 Bluehird is in the east. It nests in similar locations and its eggs are scarcely 

 distinguishable, although averaging a trifle darker in shade; size .80 x .60. 



767a. Chestnut-backed Bluebird. Sialia mexicana hairdi. 



Range. — Rocky Mountain region from Mexico to Wyoming. 

 The nesting habits or eggs of this brighter colored bird do not differ from 

 those of the last species. 



767b- San Pedro Bluebird. Sialia mexicana anabelce. 



Range. — San Pedro Martir Mountains in Lower California. 

 The eggs of this variety will not in all probability be any different from those 

 of the preceding Bluebirds. 



768. Mountain Bluebird. Sialia currucoides. 



Range. — Rocky Mountatin region, breeding from New Mexico north to Great 

 Slave Lake; winters in southwestern United States and Mexico. 



This azure blue species is common in the greater part of its range and is found 

 west to the Sierra Nevadas in California. Like the eastern Bluebird they nest 

 in holes in trees or anywhere that they can find a suitable cavity or crevice. 

 Their eggs are slightly larger than those of the other Bluebirds and have a 

 slight greenish tint; size .85 x .64-. 



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