BIRDS OF COLORADO. 



103 



558. Zonotrichia albicollis. White-throated Sparrow. 



Migratory; rare. The only records for Colorado of this 

 eastern species are the one shot by C. W. Beckham at Pueblo, 

 October 24, 1886 (Auk, IV. 1887, 120), and the one taken by 

 H. G. Smith near Denver October 5, 1892. (Nidologist, III. 

 1896-7, 76.) Since it has been taken as a rare migrant on the 

 Platte in Wyoming and is known to breed in northern Wyoming, 

 it is probable that more pass through Colorado in migration 

 than would be supposed from the meagreness of the record. 



559a. Spizella monticola ochracea. Western Tree 

 Sparrow. 



Winter resident; common. Spends the winter on the 

 plains and in the lower parts of the mountains. Common to 

 7,000 feet and occasionally to 9,000. Arrives from the north 

 about the middle of October and becomes common early in 

 November. The bulk leave in April and the last by the first 

 of May. The western form is found over all the plains to 

 Kansas. 



560. Spizella socialis. Chipping Sparrow. 



Summer resident, rare; in migration, not uncommon. 

 The typical Chippy of the east comes into Colorado as far as 

 the foothills of the Rocky Mountains. There is no authentic 

 record as high as 6,000 feet. The western variety, arisonce, is 

 the prevailing form at the base of the mountains and for several 

 miles out on the plains. There is need of much more infor- 

 mation as to the relative distribution of the two birds in eastern 

 Colorado. Though not uncommon during migration, the typi- 

 cal form must be quite rare as a breeder. There is indeed no 

 unquestionable record of its breeding in Colorado and it is en- 

 tered above as a summer resident on the strength of its known 

 breeding to the east and the north in Kansas and Nebraska. 

 Arrives in northern Colorado the last of April. 



560a. Spizella socialis arizonae. Western Chipping 



Sparrow. 



Summer resident ; abundant. Especially common along 

 the foothills in migration. Allen and Brewster mention a flock 

 of at least 1,000 birds seen May 13 at Colorado Springs. Not 

 known to breed far out on the plains, but it breeds from the 

 base of the foothills to nearly 10,000 feet. Breeds most com- 

 monly from 6,000 to 7,000 feet. Arrives the middle of April 

 and most go into the foothills by the middle of May. Breeds 

 the middle of June. Leaves the State the latter part of October. 

 Six specimens taken by Capt. P. M. Thorne at Fort Lyon have 

 been identified as this variety, but they are known there only 

 during migration. 



