1942 THE DIURNAL BIRDS OF PREY 



female reaches twenty-three inches. In the Iceland falcon {F. islandicus) the beak 

 and claws are of a dusky-horn color, and the plumage darker than the last; its 

 ground color being brown in the young and gray in the adult. Moreover, in the 

 adult the flanks have transverse arrowhead dark bars, and the tail is likewise 

 barred; the crown of the head being lighter colored than the back. In young birds 

 the dark markings on the under parts are longitudinal; this change from longitudi- 

 nal to transverse bars being common in the group. The home of this bird is Ice- 

 land, from which a certain number of individuals migrate to the southeast, a few 

 from time to time reaching Britain. The Norway, or true, gerfalcon (F. gyrfalco) 

 is a somewhat larger bird than the last, with the crown of the head as dark as or 

 even darker than the back, and the whole tone of the plumage tending more to 

 brown. It has also frequently a distinct cheek stripe, while the wings are relatively 

 longer, and the tail shorter. This falcon inhabits all Northern Europe and Asia, as 

 well as North America, and migrates southward in winter, although not reaching 

 Britain. It is replaced on the Labrador coast by the still darker Labrador falcon. 

 The habits of all the gerfalcons are probably very similar; although, from the gen- 

 eral absence of trees in its native country, the Greenland species is compelled to 

 breed exclusively on cliffs, while the others often resort to trees. The eggs are 

 usually three or four in number, and are of a creamy-white ground color, blotched 

 with cinnamon or reddish brown. All of them are extremely shy, but display great 

 boldness in defense of their nest, circling round the head of the aggressor with loud 

 screams. When sitting on its nest in the snow, with its white breast toward the 

 hunter, the Greenland falcon will often escape detection. Their prey consists chiefly 

 of waterfowl and ptarmigan. Gerfalcons, and especially the white kind, were form- 

 erly much esteemed in falconry, and commanded high prices; the white Greenlan 

 falcons exported to the Continent being captured in Iceland. Although larger and * 

 more powerful birds, all the gerfalcons lack the supreme dash and " go " of the 

 peregrine, and their former estimation was probably mainly owing to their size and 

 beauty. 



The large and handsome falcon, known as the saker (Falco sacer), a 

 Saker Falcon 



term apparently derived from the Arabic, is a southern form, agreeing 



with the gerfalcons in the proportionate length of its toes and wings, but differing 

 markedly in its plumage. In length the male saker measures upward of eighteen 

 and one-half inches, while the female falls but little short of twenty-five inches. By 

 this large size and the relative length of the claws, the saker may be readily distin- 

 guished from all the other falcons of Europe and Asia. In its ordinary dress, as 

 shown in the accompanying figure, it is further characterized by the upper surface 

 of the tail feathers, instead of being completely barred, having whitish bars on the 

 inner webs, and spots on the outer ones, these spots being especially marked in the 

 middle pair. Then again the cheek stripe, if present at all, is very narrow. The 

 head is pale rufous, sometimes turning nearly white, with narrow black stripes 

 along the middle of the feathers. The general color of the upper parts is pale 

 brown, with the feathers margined with rufous; while the quills are darker brown, 

 with white or rufous markings, and the pale tail ornamented in the manner noticed. 

 The sides of the face and throat are white, while the rest of the under parts are 



