434 



black. 1 The mature markings are gradually assumed, the 

 mottled feathers first disappearing from the back and upper 

 parts of the wings. A second year's bird, showing the 

 dark wings, and still retaining most of the chequered 

 plumes of the under parts, appears on a dull, wintry day 

 almost as dark as a Great Skua. The tail of the Lesser 

 Black-backed Gull remains banded for several seasons, 

 breaking up into mottlings before becoming pure white. 

 The adult plumage is not completed until the fourth year. 



BEAK. Yellow, red at the angle. 



FEET. Bright lemon-yellow. 



IRIDES. Pale straw-colour. 



AVERAGE MEASUREMENTS. 



TOTAL LENGTH 22 in. Female smaller. 



WING 16 



BEAK 2'5 



TAKSO-METATARSUS ... 2'6 ,, 



EGG 2'9 x 1'9 in. 



Allied Species and Representative Forms. L. affinis, 

 larger, with a coarser foot, and with paler back and wings, 

 called the Siberian Kiver Gull, is the Eastern representative. 

 L. occidentalis^ with a very stout beak, and darker back and 

 wings than in L. affinis, inhabits the Pacific Coast of North 

 America. 



GREAT BLACK-BACKED GULL. Larus marinus (Linnaeus). 



Coloured Figures. Gould, 'Birds of Great Britain,' vol. v, pi. 

 55 ; Dresser, ' Birds of Europe,' vol. viii, pi. 604 ; Lilford, 

 ' Coloured Figures/ vol. vi, pi. 25 ; Booth, ' Rough Notes,' 

 vol. iii, pi. 37. 



This majestic bird, the largest of our indigenous Gulls, 



1 This distinction can only be arrived at when the two immature 

 species are examined together in the hand. On the wing it is most 

 difficult to discriminate between them after they have left their breeding- 

 grounds and have taken to the coast. However, in August and early 

 September, young Lesser Black-backed Gulls in dappled plumage may 

 be seen following a parent, or, at all events, an adult of its own kind, 

 and this is, I have found by experience, an opportune moment for 

 securing a specimen of this bird. 



