Subfamily FALCONING. Falcons. 



Genus FALCO Linnaeus. 



Subgenus HIEROFALCO Cuvieb. 



FALCO ISLANDUS Brunn. 



151. White Gyrfalcon. (353) 



One of the largest and most powerful of the Falconina. Feet, very stout ; 

 tarsus, rather longer than the middle toe without claw, feathered fully half way 

 down in front and on sides, with narrow bare strip behind ; elsewhere, seticulate. 

 Wing, pointed by second quill, supported nearly to the end of the third, only 

 the first decidedly emarginate on inner web. Tail, rounded; sexes, alike. 

 roMre;/.— Little different. Wing of male, 13.50-14.50; tail, 8.50-9.50. Wing 

 of female, 15-16 ; tail, 9-10. Adulls: — General plumage of upper parts, barred 

 with dark brown and pale ash, the former predominating, especially on the 

 head and neck ; tail, closely barred with light and dark in about equal amounts t 



