22 BIRDS OF THE ROCKIES 



I was almost thrown into transports at finding the 

 white-crowns, listening to their rhythmic choruses, and 

 discovering their grass-lined nests by the side of the 

 babbling mountain brook. Altitude accomplishes for 

 these birds what latitude does for their brothers and 

 sisters of eastern North America. 



There is almost endless variety in the avi-faunal life of 

 the Rockies. Some species breed far above timber-line 

 in the thickets that invade the open valleys, or clamber 

 far up the steep mountain sides. Others ascend still 

 higher, building their nests on the bald summits of the 

 loftiest peaks at an altitude of fourteen thousand feet and 

 more, living all summer long in an atmosphere that is as 

 rare as it is refreshing and pure. Among these alpine 

 dwellers may be mentioned the brown-capped leuco- 

 stictes, which shall be accorded the attention they 

 deserve in another chapter. Then, there are species 

 which have representatives both on the plains and 

 far up in the mountain parks and valleys, such as the 

 western robin, the western meadow-lark, and the moun- 

 tain bluebird. 



In this wonderful country there is to be observed every 

 style of migratory habit. A twofold migrating current 

 must be noticed. While there is a movement up and 

 down the mountain heights, there is at the same time a 

 movement north and south, making the migratory system 

 a perfect network of lines of travel. Some species sum- 



