106 A PRACTICAL HANDBOOK OF BRITISH BIRDS.' 



Nestling. — (Not examined.) 



Juvenile.- — Some examples as dark as juvenile F. r. rusticolus 

 or F. r. islandus. Otheis considerably whiter on crown ; rest of 

 upper -parts with white or buffish-white edgings and spots and 

 usually bars on scapulars ; tail more widely and evenly barred 

 white ; under-parts more finely streaked dark brown. From such 

 examples there is, as in the adult, complete gradation to individuals 

 entirely white on under-parts or with only a few fine brown streaks ; 

 crown and nape white with dark brown shafts ; mantle, scapulars 

 and wing-coverts white with dark brown shafts and brown streaks 

 usually more or less drop -shaped ; tail white ; wing-feathers as 

 adult white form but usually more barred with dark brown. Such 

 birds are distinguishable from adults by having streaks instead of 

 bars on upper -parts and these are usually paler brown and not so 

 blackish. 



First winter. — Like juvenile. First summer. — The juvenile 

 plumage is completely moulted from June (when bird is about a 

 year old) to December, moult being sometimes nearly complete 

 as early as July. New plumage like adult and moulting specimens 

 examined show that dark juveniles moult into dark adult plumage 

 and whiter juveniles into white adults. 



Measurements and structure— $ wing 360-405 mm., tail 190- 

 225, tarsus 60-71, bill from cere 23-25 (12 adults measured). § wing 

 400-425, bill 25-28 (20 adults measured). Primaries : 2nd longest, 

 1st 15-25 mm. shorter, 3rd 2-10 shorter, 4th 25-30 shorter, 5th 

 45-50 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. 



Breeding-habits. — Necessarily cliff -breeder ; breeding beyond tree 

 limit. No true nest, but as same site is occupied year after year, 

 heaps of pellets and excrement in time form substantial eyrie. 

 Eggs. — Normally 4, sometimes 3 only, and 5 once recorded, closely 

 resembling those of Gyr -Falcon, and in a series darker than those 

 of Iceland Falcon. Average of 90 eggs, 58.7 X 45.7. Max. : 

 63.8 x 47, and 60.7 X 49.5. Min. : 53.5 X 44.5 and 56.9 X 41.4. 

 Breeding-season. — Variable according to locality, but eggs usually 

 in late April or May : in high latitudes not till end May. Incubation. 

 — Chiefly at any rate by female : period about 29 days (Manniche). 

 Single brooded. 



Food. — In Greenland mainly lemmings : also Alpine hare, occa- 

 sionally Ptarmigan, Turnstone, Ringed Plover, Snow-Bunting, 

 and at some eyries mainly Guillemots. In British Isles recorded 

 as taking rabbit, water-vole, Snow-Bunting, Lark, Rock-Dove, 

 Pigeon, waders (Golden Plover, Snipe, Dunlin, Ringed Plover, etc.) 

 and Kittiwake. 



