126 BIRDS OF COLORADO. 



is a fair presumption that the Robins of Colorado as a whole are 

 propinqua^ and that a few of those on the plains east of the 

 mountains should be referred to migratoria. It is not possible 

 to make any distinction between the two forms as regards mi- 

 gration and breeding. 



761a. Merula migratoria propinqua. Western Robin. 



Summer resident; abundant. The prevailing form pf 

 western Colorado, though specimens have been taken by Capt. 

 P. M. Thorne at Fort L^yon, and it is known as a rare visitant 

 to western Kansas. Much more common in the foothills and on 

 the western edge of the plains than farther east. Arrives from 

 the middle of March to the middle of April, according to the 

 season, and sometimes a few winter in southern Colorado. Nest- 

 ing begins the first of May and often two broods are reared, the 

 latter early in July. Breeds on the plains and to 11,000 feet. 

 The bulk leave the State late in November. In January, 1897, 

 a few were seen at 8,000 feet among the pines of Boulder County. 



765. Saxicola oenanthe. Wheatear. 



Accidental. A European species, straggling to New Eng- 

 land and once taken by Minot at Boulder, May 14, 1880. 

 (B. N. O. C. V. 1880, 223.) 



766. Sialia sialis. Bluebird. 



Summer resident; rare. The eastern form comes west to 

 the base of the Rocky Mountains, thence westward its place 

 being taken by 5". m. bairdi. According to Capt. P. M. Thorne 

 it nested at Fort Lyon the summer of i'-86. Beckham took it 

 at Pueblo, Aiken in El Paso County. There dre both male and 

 female in the Maxwell Collection, while Mr. Dennis Gale in- 

 forms the present writer that he has several times taken it at 

 Gold Hill fairly within the foothills of the Rockies. Arrives 

 the last of April. 



767a. Sialia mexicana bairdi. Chestnut-backed Blue- 

 bird. 



Summer resident; not common. Comes east as far as 

 Pueblo, where it occurs in both spring and fall migration. Not 

 uncommon along the base of the foothills and breeds from there 

 up the mountains to 9,500 feet. Arrives the last of March and 

 breeds about the middle of May. 



768. Sialia arctica. Mountain Bluebird. 



Summer resident; abundant. The most common Bluebird 

 of Colorado, far outnumbering both the other kinds. Common 

 in migration as far east as Fort Lyon and even to Kansas. Ar- 

 rives in February to the middle of March according to the 



