BIRDS OF COLORADO. 75 



337b. Buteo borealis calurus. Western Red-tail. 



Resident; abundant. Is the common Rocky Mountain 

 form overlapping the range of Krider's Hawk and breeding 

 from the plains to 13,000 feet in the mountains. Is one of the 

 most common hawks of the State through the summer and not a 

 few spend the winter in Colorado. 



337d. Buteo borealis harlani. Harlan's Hawk. 



Winter visitant; rare. One specimen taken by C. E- 

 Aiken at Colorado Springs. (Ridgway, Auk, II. 1885, 165.) 

 One was probably taken by Capt. P. M. Thorne at Fort Lyon. 



339b. Buteo lineatus elegans. Red-bellied Hawk. 



Migratory; rare. Included in the list of Colorado birds 

 on the strength of the following note from Geo. F. Breninger: 

 " I saw one at Table Rock, a full plumaged bird with the breast 

 to me; saw one at Fort Collins. I have handled them here 

 in California and there is not the least doubt in the matter.'" 



342. Buteo swainsoni. Swainson's Hawk. 



Resident; common. More common on the plains than in 

 the mountains. Breeds throughout the State everywhere 

 below 11,000 feet. Begins building its nest the last of April, 

 eggs are laid the middle of May and the young appear early in 

 June. Sometimes very abundant locally. A. S. Bennet of Lay, 

 Colo., says he saw a flock of five hundred July 10, 1889. 



347a. Archibuteo lagopus sancti-johannis. American 



Rough- LEGGED Hawk. 



Winter resident; not uncommon. Arrives from the north 

 in November and remains until March. Is usually found in the 

 lower parts of the mountains and on the plains. 



348. Archibuteo ferrugineous. Ferruginous Rough-leg. 

 Resident; rather common. Breeds both in mountains and 



on plains, but in the winter is mostly confined to the plains 

 and the lower streams below 6,000 feet. Breeds at least as far 

 south as Pueblo and thence to British America. Eggs have 

 been taken in Colorado as early as April 13, and well-grown 

 young by May 24; but three to four weeks later than these dates 

 is the more common time. 



349. Aquila chrysaetos. Golden Eagle. 



Resident; common in favorable localities. In few, if any, 

 parts of the United States is the Golden Eagle more common 

 than in the more mountainous portions of Colorado. They 

 breed from the foothills to at least 12,500 feet. In the winter 

 they wander occasionally over the plains, but are also found in 



