THE ICELAND FALCON. 103 



3rd 6-10 shorter, 4th 20-30 shorter, 5th 45-47 shorter ; 2nd and 

 3rd emarginated outer webs, 1st very abruptly emarginated and 

 attenuated near tip of inner web and 2nd not so abruptly. Rest 

 of structure as Peregrine Falcon. 



Soft parts. — Bill bluish-horn, darker at tip, yellowish at base ; 

 cere, legs and feet yellow in adult, grey in young ; iris dark brown. 

 Characters and allied forms. — For differences of F. r. islandus 

 and candicans see under those forms. Forms of F. rusticolus may 

 be distinguished from F. peregrinus by their larger size, and in 

 most paler coloration and want of definite moustachial stripe. 

 Briefly Gyr -Falcon is usually darker on crown and mantle than 

 Iceland and Greenland, arid is smaller ; some Greenland Falcons 

 are like Iceland but most are very much whiter, these white 

 birds not being found breeding in Iceland. Very dark brown 

 juvenile Iceland and Greenland (H. holboelli Sharpe) are not quite 

 as blackish as darkest juvenile F. r. rusticolus, while both juvenile 

 and adult F. obsoletus (Labrador) seem even darker than F. r. 

 rusticolus, but this requires confirmation. 



Breeding-habits. — -As a rule breeds on ledges of cliffs. Wolley 

 records pair breeding in trees. Nest. — Said to be substantial, built 

 of branches and twigs and occasionally some dead grass in lining. 

 Apparently birds add to and repair nest, which may in first instance 

 have been that of Rough -legged Buzzard or Raven. Eggs. — 

 Normally 4, sometimes 3, once 5, washed yellowish tawny-brown, 

 and spotted darker reddish-brown. Some have quite a pink or 

 purplish tinge, and others show more or less of the white ground. 

 Average of 100 eggs, 58.7x45.6. Max.: 62.6x±6 and 57.3x48.5. 

 Min. : 55x45.7 and 56x48. Breeding-season. — During second 

 half of April, but incubated eggs may be found in May. 

 Incubation. — By hen. Single brooded. 



Food. — In Scandinavia chiefly Ptarmigan (Lagopus mutus), 

 Willow-Grouse (L. lagopus), also Whimbrel, Pigeon and small 

 birds. Mammals, especially lemming, but also squirrel, etc. 

 Distribution. — England. — Very rare vagrant. Two admitted by 

 Saunders : — Adult, Ma vfield (Sussex), Jan., 1845 and young, Orford 

 (Suffolk), Oct., 1867. One Hatfield Broad Oak (Essex), Dec, 1901, 

 and another Thetford Warren (Norfolk) spring, 1883, doubtfully 

 authentic {Brit. B., i, p. 321). 



Distribution. — Abroad. — North Scandinavia and Lapland, stray- 

 ing occasionally to Baltic Provinces, Poland, Germany, Denmark, 

 Heligoland, Belgium, and Holland. Said to have occurred in 

 Iceland, Greenland, and North America, but probably due to error. 



243. Falco rusticolus islandus Brunn. — THE ICELAND 

 FALCON. 



Falco Islandus Briinnich, Orn. Bor., p. 2 (1764 — partim, No. 9 only. 

 Brunnich doubtfully united the white and grey falcons, stating that the 



