White-throated Swift 249 
Description.—Sooty black above and below, with w slight greenish 
gloss, a little paler below than above; a velvety-black aroa in front of 
the eye; forehead hoary; bill black, feet dusky purplish. Length 
about 7-0; wing 7-0; tail 2-45, forked about -5; tarsus -5. 
The female resembles the male, but according to Coues has the tail 
merely forked, not emarginate. Young birds are dull black with a good 
deal of white tipping and edging, especially on the rump; abdomen 
and under tail-coverts nearly pure white. 
Distribution.— Western North America, chiefly in the mountains from 
British Columbia to southern California, east to Colorado and Nevuda. 
In winter south to Lower California and Costa Rica. 
The Black Swift has only been met with in the southern part of the 
State where, however, judging from Drew’s account, it is far from 
uncommon at high elevations in the San Juan co. It breeds in the 
cliffs from, about 10,000 to 12,000 feet, and ranges to the highest 
summits. At Howardsville it arrives towards the end of June and 
stays till September. A. K. Fisher told Bendire that he had seen 
a number of these birds above the cliffs near Trinidad in July, 1892. 
These constitute the only observations in Colorado. 
Habits—This species is generally seen in flocks, 
flymg high among the mountains, and only coming 
down near the ground after rain, in pursuit of the small 
flies (Hphemeride) on which they subsist. They are 
stated to be rather less noisy than other species, 
but in no other respect to be remarkable. Anthony, 
who noticed this bird in large numbers near Silver- 
ton, killed some females between June 25 and July 
10th with ova ready to deposit, and had no doubt 
they nested in the cliffs near by. The nest and 
eggs have been taken in similar situations in 
California. 
Genus AERONAUTES. 
Nostrils oval and not concealed; wing with the outer primary a 
little shorter than the next ; tail short, less than half the wing, slightly 
forked and not spiny; tarsus and toes feathered, hallux laterally 
directed, not reversible and jointed above the other toes; plumage 
black and white. 
One North American species only. 
