752 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



greyish to pale yellow, (3rd summer) as adult ; orbital ring and 

 eyelids (ad.) orange, (juv. to 3rd winter) pink-brown. 



Characters and allied forms. — Adult L. a. cachinnans has 

 yellow legs, for other differences see under that form ; L. a. vegae 

 (Siberia to Commander Is.) has in adult mantle and wing-coverts 

 usually darker as in L. a. cachinnans but crown in winter streaked 

 as in L. a. argentatus and grey portion of primaries even darker than 

 in L. a. argentatus, legs and feet pale yellowish -flesh or very pale 

 flesh ; L. a. atlantis* (Azores, Canaries), adult has yellow legs and 

 mantle and wing-coverts are slightly darker than in L. a. cachinnans 

 but grey portion of primaries is as dark or slightly darker than in 

 L. a. vegae ; L. a, thayeri (Arctic America) is stated to have in adult 

 less black at tips of primaries than L. a. argentatus. Distinguished 

 from L. fuscus adult by pale mantle and flesh-coloured legs, for 

 distinctions of young see under that species. 



Field -characters. — Adult not unlike Common Gull but consider- 

 ably larger ; feet flesh coloured and bill yellow with red spot on 

 gonys. In flight comparatively small white sub terminal wing -tip 

 is a good distinction. Juvenile resembles Lesser Black-backed but is 

 of slightly paler colour. Commonest species on our coasts but less 

 frequent inland than Lesser Black-backed, Common or Black- 

 headed Gulls. Garrulous ; has wailing cries common to many 

 Gulls. A soft " quee-ow " is perhaps a call, whilst at nesting -places 

 a, loud barking " haow, haow, haow " and " ag, ag, ag," seem to 

 imply alarm or defiance. 



Breeding-habits. — Nests usually in colonies on grassy tops of 

 small islands or on face of cliffs, and on Continent also among sand- 

 dunes. Nest — Large, built of any suitable material, grass, sea-weed, 

 heather, etc. Eggs. — Usually 3, sometimes 2 only, rarely 4, ground- 

 colour olive to umber -brown, occasionally pale blue, or greenish, 

 spotted and blotched with deep blackish-brown. In Scandinavia an 

 erythristic type occurs, which is not found in British Isles. Average 

 of 50 British eggs, 69.79x48.34. Max.: 83.4x47.4 and 75.8x54. 

 Min. : 62.3 X 42.7. Breeding-season. — From end April to early June, 

 but most eggs laid in May. Incubation. — Shared by both sexes. 

 Period varies from 24 to 28 days. Single brooded. 



Food. — Omnivorous in its diet : carrion (dead sheep, dogs, etc.) 

 small mammals, such as young rabbits : migrating 'and wounded 

 birds (Blackbird, Lark, Corncrake, Dunlin, etc.) : eggs of coast- 

 breeding birds especially Cormorant, Gannet, Guillemot, and 

 B,azorbill : fish, cast up on shore : mollusca (Mactra, Mytilus, Lacuna, 



* Dr. J. J. Dwight, who described this form (Amer. Mus. Nov., No. 44, 

 Sept. 6, 1922), places it as a subspecies of L. fuscus. The forms of the two 

 species L. argentatus and L. fuscus intergrade both in colour of mantle and 

 pattern of primaries and as we regard cachinnans, with its yellow legs, as a 

 subspecies of L. argentatus I consider atlantis also as a subspecies of L. 

 argentatus. — H.F.W. 



