202 Mr. H. Duniford on the Birds of 



another have always been composed of birds of its own kind. 

 Adults^ after once attaining their pearl-grey hood, never lose 

 it, though in winter it becomes rather lighter, and those 

 with white heads are immature birds, which do not attain 

 their full plumage till after their second moult. I have seen 

 many birds throughout May and June of the present year 

 with well-defined dark grey hoods. Some specimens, when 

 first killed, have a delicate faint pink tinge on their under- 

 parts, also observed in L. maculipennis, which, however, 

 quickly fades after death. The colour of the iris varies a good 

 deal in different examples, being pale grey, grey with a tinge 

 of yellow, and grey with a tinge of light wood-brown. This 

 is probably attributable to age. The narrow rim of naked 

 skin round the eye is dark coral-red ; legs and feet the same, 

 but of a duller shade ; beak rather darker than the legs. 



140. Larus MACULIPENNIS, Licht. ; Scl. et Salv. Nomencl. 

 p. 148. 



Common in the neighbourhood, except in the spring. After 

 their second moult they attain adult plumage ; previously to 

 that they very much resemble the young Larus ridibundus. 

 Their times for moulting and changes of plumage are very 

 curious. I have observed and shot adult birds in April, May, 

 and June in what is usually considered winter plumage, viz. 

 with a white head and black spot behind the eye, and from 

 June to October with perfect black hoods. It is impossible 

 to establish any thing like a hard and fast line on this subject ; 

 for I have seen adult birds in the same flock, some with white 

 and others with smoke-broAvn heads. Their moults probably 

 take place in January and February and June and July ; but 

 this doubtless depends a good deal on the age of the bird. 



This Gull was common about Baradero in April ; and one 

 fine warm evening, whilst steaming down the "riacho,"' I 

 saw a curious sight : a considerable flock of Black-headed 

 Gulls were hawking over some low marshy ground with 

 Swallow-like flight, apparently in pursuit of some sort of 

 moth ; for they kept about a foot above the ground, never 

 wandering far from each other. 



