130 THE GULLS 



marked, or with only one or two bold blotches, is not uncommon. The erythristic 

 type described under the head of herring-gull also occurs in this species, but not 

 in the British Isles, and Dr. Ottosson records a melanistic variety of the egg. 

 (PI. J.) Average size of 50 eggs, 3'04 x 2-13 in. [77'4 x 54*1 mm.]. Both sexes 

 take part in incubation, and the period is given by Faber as 28 days. The 

 breeding season in the British Isles seems to be rather irregular : as a rule the first 

 eggs are found early in May, but Mr. J. J. Dalgleish records a clutch on April 19 

 near Ardnamurchan, and many pairs do not lay apparently till the second or third 

 week in May. Only one brood is reared in the season, but second layings may be 

 found in June. [F. c. R. J.] 



5. Food. The species is omnivorous. Its food is practically the same as that 

 of the herring-gull, except that its greater strength enables it to prey upon larger 

 mammals and birds. (See for details p. 167; also Plate XLVI.) According to 

 Saunders, it will attack sickly ewes and weak lambs, and it makes short work of 

 wounded ducks and game-birds. The young are fed by both parents, but details 

 of the nature of the food given are lacking. Prom a young bird in down an eel 

 18 inches long was extracted ! (British Birds, v. p. 88.) [F. B. K.] 



GLAUCOUS- GULL [Lartis glaucus Briinnich ; Larus glaucus Fabricius. 

 Burgomaster, Iceland scorie (Shetlands) ; Great white-winged gull (Devon). 

 French, goeland bourguemestre ; German, Eis-Move ; Italian, gabbiano glauco]. 



i. Description. This species recalls the herring-gull, but may at once be dis- 

 tinguished therefrom, when adult, by the entire absence of black on the primaries. 

 The sexes are alike, and there is no marked seasonal change of coloration. (PI. 107.) 

 Length 29 in. [736-60 mm.]. The mantle and wings are of a delicate pearl-grey ; 

 the primaries pale grey fading into white at the terminal third ; the rest of the 

 plumage is pure white. The beak is yellow, with a patch of orange on the angle 

 of the lower jaw ; the rim of the eyelid is vermilion, the iris yellow, and the legs and 

 toes are bright pink. The j uvenile plumage is of a pale huffish ash, but the mantle and 

 wings are of a rich cream colour, relieved by loops of dark greyish buff. The greater 

 wing-coverts and quills are of a huffish ash ; the tail cream colour, with darker 

 irregular transverse bars. Immature birds have the head, neck, and interscapulars 

 dull white, with pale brownish ash striations. The scapulars and wing-coverts 

 cream colour, with broad submarginal loops of pale brownish ash. The secondaries 

 are tipped with white, and mottled subterminally with pale brown, the rest of 



