Henninger- Jones — On Falcones of North America. 79 



also rabbits, lemmings, hares, ptarmigans. 



Voice. 

 A piercing, almost thrilling scream, " gyak." 



Nest. 

 On inaccessible cliffs, in close vicinity of breeding water- 

 fowl ; composed of sticks, lined with moss, hay, hairs and 

 feathers. 



Eggs. 

 Laid end of May and in June, 2 to 4 — 60 x 48 mm 59.5 x 

 46.5 mm (Bendire) ; 60.45 x 43.8 mm (Davie) ; reddish white 

 ground color marked with varying shades of red ; texture 

 rough. 



Time, of incubation unknown. 



FALCO RUSTICOLUS [Linu). 



Gray Gyrfalcon. 



Two subspecies are included under this specific heading- 

 Gyrfalco, (Linn.) the Gyrfalcon, and obsolctiis, (Gmel.) the 

 Black Gyrfalcon. 



Geographical Distribution. 



Gray Gyrfalcon: northern parts of the Arctic Region (ex- 

 cept Norway and Sweden), breeding everywhere; occassion- 

 ally south in winter to the Northern United States, British Co- 

 lumbia, Wisconsin. 



Gyrfalcon : northern Europe, and in America from Labra- 

 dor and Hudson's Bay to Alaska. 



Black Gyrfalcon : coast of Labrador south to Canada, 

 Maine, Rhode Island, and New York. 



Measurements. 



Gray Gyrfalcon: Male; length 52.32, wing 35.86, tail 2L67, 

 culmen 2.29, tarsus 6.17, middle toe 5.03. 



Female; length 59.69, wing 40.13, tail 24.77, culmen 2 54, 

 tarsus 6.24, middle toe 5.23. 



