400 Cook, The Birds of Colorado. [^!, k 



153. Hylocichla alicise. CIray-cheeked Thrush. — Very rare; seen 

 only during migration and then very seldom. 



154. Hylocichla ustulata swainsoni. Olive-backed Thrush. — The 

 most common of the thrushes. It places its nest from two to twenty-five 

 feet above ground. 



155. Hylocichla guttata pallasi. Hermit Thrush. — Very rare. 

 Seen only during migration. 



156. Planesticus migratorius. Robin. — Very common. This bird 

 nests almost as abundantly in the deep woods as in the more open and 

 settled portions. Two broods are usually raised. 



157. Sialia currucoides. Mountain Bluebird. — Very common in 

 the open portions of the country but never seen in the heavily wooded 

 sections. Two broods are raised. 



THE BIRDS OF COLORADO — THIRD SUPPLEMENT. 



BY WELLS W. COOKE. 



The original 'Birds of Colorado' was published in 1S97 as 

 Bulletin No. 37 of the Colorado State Agricultural Experiment 

 Station. It was followed a year later by the first supplement as 

 Bulletin No. 44 of the same institution, and the second supplement 

 was published in 1900 as Bulletin No. 56. The original bulletin 

 enumerated 363 species as occurring in Colorado, of which 230 

 were known to breed in the State. The next year the total was 

 increased to 374 and the breeders to 236. The year 1900 showed 

 387 species known to occur in the State, with 243 breeders. 



The present publication withdraws 12 of these 3S7 as having been 

 admitted to the State list on insufficient evidence or as not now 

 considered valid forms. At the same time it recognizes 22 addi- 

 tional species as entitled to a place in the State list. Thus the 

 present known avifauna of Colorado totals 397 species — a number 

 probably exceeded by only two States, California and Texas. It is 

 interesting to note that of these 22 additions, 9 had been mentioned 

 in the second supplement as likely to occur in Colorado, while the 

 other 13 are unexpected additions or arise from the recognition of 

 subspecific forms. The number of species now known to breed in 



