Bird Life of Yosemite Park. 251 



with their queer hoarse calls and general airs of pro- 

 prietorship and curiosity, will claim the attention of the 

 most casual observer, even though spread out about him 

 stretch measureless leagues of tortured mountain ranges, 

 of bewildering gulfs of granite, of somber forests of 

 pine, and wastes of snow. 



The sheer cliff walls of the Yosemite are the breeding- 

 place of flocks of those peerless aerial voyagers, the 

 white-throated swifts. They are first cousins of the 

 familiar chimney swallovv, so called, of the Eastern States, 

 and are more or less related to groups as widely dif- 

 ferent in habits and appearance as the whip-poor-wills 

 and humming-birds. In coloration the white-throated 

 swift is as unpretentious as the nut-cracker, its upper 

 parts being blackish brown, and its under parts white. 

 The under-tail coverts are dark, however, and the wings 

 are varied, with white patches. The extraordinary thing 

 about the swift is its impetuous flight, its endless rush 

 through the air on rapidly vibrating wings, the velocity 

 of its darting hither and thither after insect prey. As 

 we look up at the dizzy heights of the vertical parapets 

 of granite, we may descry a flock of these accomplished 

 aeronauts, sporting high aloft as care-free as a crowd of 

 children at play, and catch the incessant chattering calls 

 floating down to us as from another world. Their nests 

 are built of sticks, gummed to the cliff walls with their 

 saliva, so their babies are born cliff-dwellers and fledged 

 upon the heights of fear. 



In the Yosemite Valley the cliffs rise so abruptly that 

 birds of the Alpine Zone are brought into more intimate 

 relationship with the characteristic forms of lower levels. 

 It is so easy for birds to fly down from the rim of the 

 gorge to that entrancing valley where they may disport 

 beside the still water in meadows green. Thus the junco 

 or snow-bird (Thurber's junco the books call it) is to be 

 expected at a higher level than the floor of the valley, 

 but cannot resist the temptation to stray into this para- 

 dise. The junco is a member of that large group, the 



