BIRDS OF BOULDER COUNTY, COLORADO 2O0. 



Zonotrichia leucophrys gambeli, Gambel's Sparrow (5543) 



Winter resident; abundant on the Plains during migration and infrequent 

 in winter. Single birds have been noted in migration in the lower part of the 

 Mountain zone but they appear to be rare outside of the plains. Migrants arrive 

 March 20 and have been noted as late as May 8; in the fall they arrive September 

 10-22 (3 records), and leave by the first of November. 



Spizella monticola ochracea, Western Tree Sparrow (5590) 



Winter resident; abundant on the Plains and occasionally found in the 

 lower part of the Yellow Pine zone. Arrives, October 13-22 (4 records); leaves, 

 March 12 — April 7 (3 records). 



Spizella passerina arizonae, Western Chipping Sparrow (560a) 



Summer resident; abundant in migration and common in summer from the 

 Plains to the lower part of the Mountain zone. Arrives, April 26-30 (4 records) ; 

 leaves, October 1-16 (4 records). Gale recorded a nest on July 8, 1890, at about 

 10,000 feet. Widmann found it from 6,000 to 9,000 feet near Estes Park. 



[Spizella pallida, Clay-colored Sparrow (561)] 



Kellogg (1889) secured a specimen just north of the county in Estes Park, 

 August 10. Also observed by Widmann at the same place in the summer of 1910. 

 Dean Babcock of Estes Park stated that he had seen the species there in 1912. It 

 is, therefore, quite surely a regular migrant in the county and probably a summer 

 resident in restricted localities. 



Spizella breweri, Brewer's Sparrow (562) 



Migrant ; common on the Plains. Henderson took two in September at 10,000 

 feet. It has been seen as early as May 5 and as late as September 25. It has been 

 noted on July 9 and August 6 and may be found to breed sparingly in the county. 



Junco aikeni, White-winged Junco (566) 



Winter resident; common in the Yellow Pine zone and along the edge of the 

 Plains. Arrives, October 17-27 (4 records) ; leaves, March 13 — April 8 (4 records). 

 Cary reported a nest with young birds on June n, 1905, found by Walter 

 Blanchard in the Yellow Pine at about 7,000 feet near Magnolia; this is the only 

 summer record for the region. Gale observed the species at 10,000 feet in migra- 

 tion in April. 



Junco hyemalis hyemalis, Slate-colored Junco (567) 



There are two specimens in the University collection from Boulder, one taken 

 January 8, 1904, by Mr. Juday and one not dated. The species apparently occurs 

 regularly in the state in migration and may have been overlooked in the county. 



