UP AND DOWN THE HEIGHTS 23 



mer in the mountains and winter on the plains ; others 

 summer in the mountains pass down to the plains in the 

 autumn, then wing their way farther south into New 

 Mexico, Mexico, Central America, and even South 

 America, where they spend the winter, reversing this 

 order on their return to the north in the spring ; others 

 simply pass through this region in their vernal and 

 autumnal pilgrimages, stopping for a short time, but 

 spending neither the summer nor the winter in this 

 latitude ; still others come down from the remote north 

 on the approach of autumn, and winter in this State, 

 either on the plains or in the sheltering ravines and 

 forests of the mountains, and then return to the north 

 in the spring ; and, lastly, there are species that remain 

 here all the year round, some of them in the moun- 

 tains, others on the plains, and others again in both 

 localities. A number of hardy birds genuine feath- 

 ered Norsemen brave the arctic winters of the upper 

 mountain regions, fairly revelling in the swirling snow- 

 storms, and it must be a terrific gale indeed that will 

 drive them down from their favorite habitats toward 

 the plains. 



Does the avi-fauna of the Rocky Mountain district 

 differ widely from that of the Eastern States ? The 

 reply must be made in the affirmative. Therefore the 

 first work of the bird-student from the East will be that 

 of a tyro the identification of species. For this 



