86 
BIRDS OF COLORADO. 
higher up, but is still common to 10,000 feet. Reaches northern 
Colorado the last of May and nests by the middle of June. 
Eastern Colorado is within the geographical range of C v. 
sennetti^ but it has not yet been reported from the State. 
422. Cypseloides niger borealis. Black Swift. 
Summer resident; abundant, locally. Occurs regularly in 
southwestern Colorado, where it was found by F. M. Drew, who 
says that they come late in June and leave late in September; 
breed from 10,000 to 12,000 feet, and range far above 13,000 
feet. Are very common and always hunt in large flocks. 
(B. N. O. C. VII. 1882, 182 and B. N. O. C. VI. 1881, 85 and 138.) 
Has been taken by Dr. A. K. Fisher as far east as Trinidad. 
(Bendire, Hist. N. Am. Birds, Part II. 175.) 
455. Aeronautes melanoleucus. White-throated Swift. 
Summer resident; not uncommon, locally. Breeds only 
in inaccessible rocks from the lower foothills at about 6,000 
feet to at least 12,000 feet if not higher. Arrives the last of 
March to the middle of April. More common in the southern 
half of the State, but breeds at 7,000 feet on Horsetooth Mount- 
ain a few miles from Fort Collins and passes north into Wy- 
oming. 
429. Trochilus alexandri. Black-chinned Hummingbird. 
Summer resident; not uncommon, locally. Occurs only in 
the extreme western and southwestern part of Colorado, and 
there only in the lower portions below 6,000 feet. 
432. Selasphorus platycercus. Broad-tailed Humming- 
bird. 
Summer resident; common. The most common Hum- 
mer in Colorado. Arrives early in May and breeds from the 
foothills to 11,000 feet. Ranges 2,000 feet above timber-line in 
summer time. Breeds most commonly from 7,000 to 9,000 feet. 
First set of eggs is laid about the middle of June and, at least 
in southern Colorado, two broods are reared. The young from 
the later brood are scarcely out of the nest by the middle of 
August and a few weeks later the birds start southward. Re- 
cords are lacking for the plains region east of the foothills, 
though common clear to the edge of the plains. 
433. Selasphorus rufus. Rufous Hummingbird. 
Summer resident ; not uncommon locally. A western 
species coming into southwestern Colorado, where it breeds 
from 7,000 to 10,000 feet and ranges in summer several 
thousand feet higher. Tolerably common in western Colorado 
and much less common along the eastern slope of the mountains. 
