654 GREAT BLACK-HEADED GULL. 



E. long.), an elevated lake in the mountain range between Mongolia 

 and China ; and it is probably found throughout Tibet in summer, 

 as it passes over Gilgit on its way to India, where it frequents the 

 rivers and coasts down to Ceylon and Burma during the cold 

 season. It is unknown on the Arnoor or along the sea-board of 

 China, and Cassin's record from Japan is the result of an erroneous 

 identification. 



Little is known respecting the breeding habits of this bird, though 

 numbers of its eggs have been received through the Moravian 

 colony at Sarepta on the Lower Volga ; these, laid on the bare sand, 

 are 3 in number, and stone-drab in colour, boldly streaked and 

 blotched with umber and black: average measurements 2 '95 by 

 2 in. The cry is described as a harsh and raven-like croak ; the 

 food consists of fish, crustaceans, locusts, reptiles &c. 



The adult in breeding-plumage has the head jet-black ; mantle 

 of a darker grey than in L. ridibundus ; secondaries with broad 

 white tips, which form a conspicuous alar bar ; primaries chiefly 

 white, barred with black from the ist to the 5th and slightly on the 

 6th ; tail and under parts white ; bill orange-yellow, red at the 

 angle and zoned with black ; legs and feet greenish-yellow, webs 

 orange. There is considerable variation in size, and females are 

 often so much smaller than males as to have given rise to the belief 

 that they belonged to a distinct species; length of a male 27 in., 

 wing 19 in. In winter the head is merely streaked with blackish. 

 The young bird is mottled with brown on the upper parts, and 

 the primaries are dusky-brown ; it may be distinguished from 

 members of the Herring-Gull group of the same size by the 7ci/ii/e 

 margi/is to the secondaries, extending for a long way up both 

 loebs ; also by the uniformity in the dark band which crosses the 

 tail, this band being mottled and broken up in other species. 

 The nestling differs from that of almost all the Gulls in being of 

 an unspotted greyish-white above, and clearer white below. 



The Gulls with hoods have been separated from the rest under 

 various generic names. The least objectionable is Chrdicocephalus 

 of Eyton, based upon "coloured hood, small size, and more naked 

 tibia"; but the second qualification does not suit the above gigantic 

 species, for which therefore, Kaup created the genus Ichthyactiis. 

 No term can be more inadmissible than Xeiiia, as it should only be 

 applied to a Gull with a forked tail. 



