108 EGGS OF BRITISH BIRDS. 



THE BLACK-HEADED GULL. 

 (Lams ridibundus.) 



Plate 34, Figs. 1, 2. 



The Black-headed Gull is one of our commonest species. Its 

 colonies are not so large as those of the Kittiwake, but they are 

 much more numerous. It is a resident in the British Islands, 

 frequenting the coasts during winter, but retiring inland in 

 summer to breed in colonies in swamps. It is an inland species, 

 breeding throughout the temperate portions of the Palgearctic 

 region. 



The nests are very slight structures, mere depressions in the 

 spongy ground. Occasionally the eggs are laid on the bare 

 ground, but there is generally a lining of dead grass, sedge, or 

 other weed. 



Very few birds are subject to greater variation in the colour of 

 their eggs than the Black-headed Gull. The eggs vary in number 

 from two to three, and four are occasionally found. Sometimes 

 the eggs in one clutch are very much alike ; but occasionally one 

 of the eggs is quite different from the rest, both in the ground- 

 colour and in the style of spotting. Probably in the latter cases 

 the odd egg has been laid by a different bird. The eggs vary in 

 ground-colour from pale bluish-green to greyish-buff and brown, 

 spotted, blotched, and streaked, in almost every conceivable 

 variety, with surface-markings of dark brown, and with under- 

 lying markings of greyish-brown. On some eggs the spots are 

 much darker than on others, and occasionally, but apparently only 

 where the ground-colour is pale bluish-green, they are absent or 

 nearly so. They differ greatly in shape and size, varying from 

 '245 to 1'95 inch in length, and from 155 to 1"35 inch in breadth. 



THE ADKIATIC BLACK-HEADED GULL. 



(Larus melanocepJialits.) 

 Plate 34, Figs. 3, 4. 



Two specimens of this Gull have been obtained in England. 

 One was shot on Breydon Broads in Norfolk in December, 1886, 

 and another was obtained near Barking Creek in January, 1866, 



