LIFE HISTORIES OF NORTH AMERICAN BIRDS 



OF PREY 



(Part 2) 

 ORDERS FALCONIFORMES AND STRIGIFORMES 



By Arthur Cleveland Bent 



Taunton, Massachusetts 



Order FALCONIFORMES 

 Family FALCONIDAE: Caracaras and Falcons 



FALCO RUSTICOLUS CANDICANS Gmelin 



white gyrfalcon 



Plates 1-4 



HABITS 



The gyrfalcons have always been a very puzzling group; their 

 nomenclature has been confusing, their relationships have never been 

 well understood, and confusion as to the distribution of the different 

 forms has been even worse. Various views on all these points have 

 been expressed by different writers, but none of them are conclusive 

 or wholly satisfactory. Until we have available a considerable series 

 of breeding birds, both adults and their young, collected in various 

 parts of the breeding ranges, we shall never fully understand the rela- 

 tionships of the various forms and their ranges. Most of the speci- 

 mens in collections are late fall or winter birds, which may have wan- 

 dered far from their native ranges. Even summer specimens are not 

 necessarily breeding birds, as immature birds and nonbreeding adults 

 are often widely scattered in summer. We need also a series of young 

 birds in juvenal plumage, taken before, or soon after, the flight stage 

 is reached, to help us recognize with certainty the immature plumages 

 of the different races. 



At one time the white gyrfalcons of northern Greenland were con- 

 sidered as specifically distinct from the gray forms, but it now seems 

 to be generally conceded that all the forms are races of one species, 



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