126 
BIRDS OF COLORADO. 
is a fair presumption that the Robins of Colorado as a whole are 
propmqua^ 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 of 
western Colorado, though specimens have been taken by Capt. 
P. M. Thorne at Fort Lyon, 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 cenanthe. Wheatear. 
Accidental. A European species, straggling to New Eng- 
land and once taken bv 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 A. 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 are 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 
