204 UNIVERSITY OF COLORADO STUDIES 



Family ICTERIDAE, The Blackbirds, Orioles, etc. 

 Dolichonyx oryzivorus, Bobolink (494) 



Summer resident; local in the bottomlands on the Plains near Boulder. 

 Arrives, May 24-28 (5 records); latest fall date September 9. Henderson first 

 noticed it in the county in 1904. There seems to be no reason to doubt that it 

 nests, though eggs have not been taken. Widmann noted one male in Estes Park, 

 June 15, 1910. 

 Molothrus ater ater, Cowbird (495) 



Summer resident; common on the Plains, and occurring in the Yellow Pine 

 "up to 8,000 feet or more" (Henderson). Arrives, May 7-10 (3 records); latest 

 fall date available August 21. Gale found eggs between May 31 and July 3 in 

 the nests of Traill's Flycatcher, Thick-billed Red-wing, Brewer's Blackbird, Black- 

 headed Grosbeak, Yellow Warbler and Western Yellow- throat. Widmann 

 observed a male at Estes Park in July, 19 10. 

 Xanthocephalus xanthocephalus, Yellow-headed Blackbird (497) 



Summer resident ; common in the marshes of the Plains. Arrives, April 7-1 7 

 (2 records); leaves, September 12-24 (3 records); the latest date seen is October 

 30, 1910. Eggs have been found between May 10 and June 13 by Gale (8 sets in 

 the University collection are dated May 10, 1886). Professor Ramaley saw one 

 bird at Tolland in Gilpin County (9,000 feet) in August, 191 1, and Gale listed it 

 as a mountain bird, without definite data. 

 Agelaius phoeniceus fortis, Thick-billed Red-wing (498^) 



Permanent resident; abundant in summer on the Plains and common in the 

 marshes of the Yellow Pine and Mountain zones at least as high as 9,200 feet at 

 Eldora Lake and 9,000 feet at Tolland. In winter, flocks of male Red-wings are 

 common on the Plains. Females arrive in migration in March and April and prob- 

 ably leave in October. Eggs have been found between May 10 and June 15. 

 Kellogg found a nest and eggs on June 21 at Estes Park. The subspecific forms 

 of summer and winter birds have not been determined for the county and all are 

 assigned to fortis. 

 Stumella neglecta, Western Meadowlark (501.1) 



Permanent resident; abundant in summer on the Plains, common in the 

 Yellow Pine and infrequent in the lower parks of the Mountain zone (Tolland. 

 9,000 feet). In winter it is common in small bands in the meadows of the Plains. 

 Eggs have been found from May 12 to June 10 (Gale). Kellogg recorded the 

 occurrence of this species above timberline near Estes Park. 

 [Icterus galbula, Baltimore Oriole (507)] 



Gale mentions in his notes under date of June 25, 1884, a nest containing five 

 eggs, presumably found in Boulder County. It is very rare in Colorado and 



