THE GYR-FALCONS. I91 



the chestnut forms small spots and larger blotches. The eggs 

 of the Merlin are often impossible to distinguish from those 

 of the Hobby, and also from those of the Kestrel, though they 

 seem never to vary to a pale form like so many of the Kestrel's 

 eggs do. Axis, i'45-i"6 inch; diam., i"i5-i*25. 



THE GYR-FALCONS. GENUS HIEROFALCO. 



Hierofalco^ Cuvier, Regne Anim. i. p. 312 (181 7). 



Type, H. candicans (Gm.). 



The Gyr-Falcons are giant Kestrels, and in the case of the 

 Saker Gyr-Falcon {Hierqfako saker) and Henderson's Gyr- Fal- 

 con {Hierofaico he?idersoni) the plumage is red and not unlike 

 that of a Kestrel. Both the Gyr-Falcons and Kestrels differ from 

 the true Falcons {Falco), as typified by the Peregrine, in having 

 the outer and inner toes about equal in length, whereas in 

 every true Falcon the outer toe is longer than the inner one. 

 The nostril in the Gyr-Falcon has always a central tubercle. 

 The tarsus is finely reticulate in front, and is not double the 

 length of the middle toe. Although the proportions of the 

 toes are the same in the Gyr-Falcons and the Kestrels, the 

 former have a somewhat less pointed wing, the distance be- 

 tween the tips of the primaries and secondaries being equal to, 

 or less than half of, the length of the tail. 



The true Gyr-Falcons are all birds of northern countries, 

 and occur throughout the whole of the arctic and sub-arctic 

 portions of the Old and New Worlds. The Kestrel-hke Gyr- 

 Falcons, H. saker, H. hendersoni, and H. mexicajius, have a 

 more southern habitat, and carry the range of the genus to 

 Mexico in the New World, and to South-eastern Europe, 

 Central Asia, and India in the Old World. 



I. THE GREENLAND GYR-FALCON. HIEROFALCO CANDICANS.* 



Falco candicans, Gmelin, Syst. Nat. i. p. 275 (1788); Newton, 

 ed. Yarr. Brit. B. i. p. 36 (187 1); Dresser, B. Eur. vi. p. 

 21, pi. 368, 369 (1876) ; Seebohm, Brit. B. i. p. 16 (1883) ; 

 Saunders, Man. Brit. B. p. 331 (1889); Lilford, Col. Fig. 

 Brit. B. part xvii. (1891). 



* This species is called Falco islmtdus of Briinnich by the American 

 ornithologists. The work, however, dates from 1764, and was therefore 

 published before the 12th edition of Linnosus in 1766, which is the recog- 



