White-throated Swift 249 



Description. — Sooty black above and below, with a slight greenish 

 gloss, a Uttle paler below than above ; a velvety-black area 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 -u. 



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, esijecially 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 Nevuxia. 

 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 Jvme 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, 

 flying high among the mountains, and only coming 

 down near the ground after rain, in pursuit of the small 

 flies (Ephemeridce) 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, sUghtly 

 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. 



