LESSER BLACK-BACKED GULL. 321 



islands, frequently mixed with a bunch or two of seaweed. On other islands 

 the nests are built on the grass, and occasionally almost hidden in the masses 

 of bladder campion, which grows in great profusion in many places. Three 

 is the usual number of eggs in each nest, but on the Fame Islands they are 

 robbed so repeatedly that when they are at last (it used to be the 18th of 

 June) allowed to finish breeding in peace, very few nests contain the full 

 clutch. The eggs vary much in size, shape, and colour. The shell varies 

 from pale bluish green to almost white, and from greyish bufC through 

 pale brown to dark brown. The surface-spots are rich dark brown, some- 

 times approaching black, and the underlying spots are brownish grey. On 

 some eggs the spots are very small and evenly distributed over the entire 

 surface ; on others they are large blotches and very few in number : they 

 are usually largest and most numerous at the large end, where they often 

 form a semi-confluent zone. In rare instances the spots assume the form 

 of fantastically shaped streaks and blotches. The eggs vary in length from 

 2'8 to 2' 4 inch, and in breadth from 2'0 to 1*7 inch. It is very important 

 that eggs of this species should be carefully identified, as many of them are 

 indistinguishable from those of the Herring-Gull. 



In winter the Lesser Black-backed Gull wanders far from its usual 

 summer haunts ; it becomes a nomad, working round the coast, following 

 the shoals of fish, sometimes visiting inland ponds or following the course 

 of large rivers. 



The Lesser Black-backed Gull is not quite so large as the Herring-Gull, 

 but more than twice the size of the Common Gull or the Kittiwake. The 

 progress to maturity in this group of Gulls is much slower than in the 

 Black-headed Gulls. The adult Lesser Black-backed Gull in summer 

 plumage has the entire head, neck, the whole of the underparts, the upper 

 tail-coverts, and the tail pure white ; the back and wing-coverts are dark 

 slate-grey ; the longest scapulars and the innermost secondaries are tipped 

 with white ; the quills are nearly black, with white tips, and the longest 

 primaries have also a subterminal white spot. Bill yellow, with a vermilion 

 patch on the angle of the lower mandible ; legs and feet yellow ; orbits 

 vermilion ; irides pale yellow. After the autumn moult the head and 

 nape are streaked with dull brown. The adult plumage is not assumed 

 until after the fourth autumn moult. After the third spring moult the 

 absence of the white subterminal spot on the longest primaries betrays the 

 immaturity of the bird ; after the third autumn moult additional signs of 

 immaturity present themselves in a few brown markings on the wing-coverts 

 and tail ; after the second spring moult the absence of the vermilion spot 

 on the lower mandible and the flesh-coloured feet and orbits are further 

 marks of immaturity ; after the first spring moult, which apparently pro- 

 ceeds so slowly that it blends with the second autumn moult, all the signs 

 of immaturity to be found in first plumage are reproduced, except that 



VOL. III. Y 



