764 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



measured). $ wing 457-470 (juv. 450-470), bill 55-61. Primaries : 

 1st narrow, pointed and about two-thirds primary-coverts, 2nd 

 and 3rd longest, 4th 15-20 mm. shorter, 5th 45-55 shorter. Rest of 

 structure as in Herring-Gull. 



Soft parts. — Bill (ad.) pale yellow, angle bright vermilion, tip 

 whitish bone-colour, gape vermilion, sometimes small dusky spot 

 near tip of lower mandible, (juv. and 1st winter and summer and 

 2nd winter) brown-black, base of lower pinkish, tip pale horn, (2nd 

 summer) as last but often some orange on angle, (3rd winter and 

 summer) base and tip yellowish-white, more or less blackish in 

 middle with varying amount of orange at angle, (4th winter) more 

 like adult but with some blackish subterminally ; legs and feet 

 livid bluish -flesh, webs pinker ; iris (ad.) very pale lemon, (juv. to 

 2nd summer) dark olive-brown, (3rd winter and summer) dark 

 brown, grey-brown or sometimes buffish -yellow ; orbital ring and 

 eyelids (ad.) vermilion, (juv. to 2nd winter) yellowish-brown, (2nd 

 summer to 3rd summer) yellowish to dull orange. 



Characters. — No subspecies. Large size and heavy bill and black 

 on primaries distinguish it from other British Gulls. 



Field -characters. — Black mantle distinguishes adult from other 

 Gulls except the paler L. f. afflnis and L. f. fuscus from which it 

 differs in its much greater size and flesh-coloured, not yellow, feet. 

 Juvenile is noticeably paler than Lesser Black-backed or even 

 Herring-Gull and is of course much larger. Very infrequent inland, 

 but occurs on all coasts singly or in small numbers at all seasons, 

 one or two being often associated in mobs of gulls that frequent 

 harbours, estuaries and low -lying shores. Cries similar to those 

 of Lesser Black-backed and Herring-Gulls ; at nesting-place the 

 guttural " ug, ug, ug," is deeper in tone than corresponding note of 

 Lesser Black-backed. 



Breeding-habits. — Where numerous sociable in breeding -habits, 

 colonies breeding on tops of stacks, islands, etc., but many pairs 

 may be found nesting singly on islets in lakes, or on coastal cliffs. 

 Nest. — Large, composed of heather, sticks, seaweed, grass, and a 

 few feathers. Eggs. — Usually 2-3, but Pearson once found 5 ; 

 ground-colour usually stone-buff to olive-brown, blotched and 

 spotted dark umber-brown and ashy. Eggs with blue ground not 

 infrequently occur and in Scandinavia an erythistic type is met with. 

 Average of 100 British eggs, 77.29x53.94. Max.: 82.1x53.3 and 

 77x57. Min. : 69.4x49 mm. Breeding -season. — From beginning 

 May to early June in British Isles. Incubation. — By both sexes. 

 Period 26-28 days. Single brooded. 



Food. — Very varied : carrion of all kinds, occasionally weakly 

 ewes or lambs, small mammals (rat, rabbit, mole, voles, etc.), birds 

 (wounded ducks of all kinds, Little Auk, Puffin, Shearwater, Petrels, 

 and smaller birds), also young of many species (Cormorant, Gulls, 

 Ducks), and eggs ; fish (including gurnard, eel, fluke and whiting), 



