48 BIRDS OF PREY. 



ceived and soon followed by his ambitious mate, and in a little 

 time, by circular ascending gyrations, they both disappeared in 

 the clear azure of the heavens ; and though I waited for their 

 re-appearance half an hour, they still continued to be wholly 

 invisible. This amusement, or predilection for the cooler 

 regions of the atmosphere, seems more or less common to all 

 the rapacious birds. In numerous instances this exercise must 

 be wholly independent of the inclination for surveying their 

 prey, as few of them besides the Falcon descend direct upon 

 their quarry. Many, as well as the present species, when on 

 the prowl fly near to the surface of the ground, and often wait 

 and watch so as to steal upon their victims before they can 

 take the alarm. Indeed the Condor frequents and nests upon 

 the summit of the Andes, above which they are seen to soar 

 in the boundless ocean of space, enjoying the invigorating and 

 rarefied atmosphere, and only descending to the plains when 

 impelled by the cravings of hunger. 



The Eastern variety of the Red-tail is a common bird through- 

 out eastern North America north to about latitude 49°, and was 

 taken by Dr. Bell at Fort Churchill, on Hudson's Bay. It ranges 

 westward to the Great Plains, where it is replaced by the sub- 

 species krideri. From the Rocky Mountains to the Pacific it is 

 represented by calnnis, and examples of this latter variety have 

 been taken, occasionally, as far east as Illinois. The Red-tail is a 

 summer resident only of the Maritime Provinces, but a few are 

 found in winter in southern Ontario and New Eng^land. 



Note. — Mr. Ridgway now considers Harlan's Hawk to be 

 a variety of the Red-tail, and he proposes to name it Biiteo borealis 

 harlaiii. Its usual habitat is along the lower Mississippi ; but exam- 

 ples have been taken in Illinois, Iowa, Pennsylvania, and Georgia. 



Two examples of Swainson's Hawk {Btiteo swahisoni), a 

 Western species, have been taken in Massachusetts, — one at 

 Wayland in 1876, and the other near Salem in 1878. 



