NATATORES. 255 



with orange eyelid, and the back and wings pale 

 grey, while all the under parts are snowy white, is 

 one of the most beautiful of all the Gulls. 



In winter the brown head disappears almost 

 entirely, a few spots or streaks only of that colour 

 remaining on the crown, ear-coverts, and nape. 

 The young birds may always be known from their 

 parents by having the grey of the back more or less 

 spotted with brown, the scapulars, particularly, pre- 

 senting a very mottled appearance, and by having 

 the tail, which is square, and in old birds pure 

 white, barred with black at the extremity. 



The Blackheaded Gull differs chiefly from others 

 of the genus in its partiality for fresh water, and in 

 its breeding inland in colonies upon the ground 

 instead of in cliffs facing the sea. Oftentimes the 

 centre of a marsh is selected, where, from the treach- 

 erous nature of the soil, the eggs are comparatively 

 safe. Elsewhere, when discovered, they are eagerly 

 carried off and sold as " Plover's eggs," and, in 

 truth, are very good eating. When visiting a breed- 

 ing station of the Blackheaded Gull during the last 

 week of May, 1864, one or two facts presented them- 

 selves which seemed worthy of note. In the first 

 place none but old birds in full summer dress were 

 breeding ; amongst several hundred I could not 

 detect a single bird in the plumage of the second 

 year. In the next place the period of laying seemed 

 uncertain, varying with different individuals, some 



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