396 ANNUAL. REPORT SMITHSONIAN INSTITUTION, 1924 



half- white bodies, bathed in sunshine and artistically posed, as if for 

 our pleasure and admiration. If there is little sun and no wind, 

 they face in various directions ; there is no uniformity in their ranks. 

 If there is a high wind, however, they turn toward the quarter 

 whence it blows, probably to prevent ruffling of their feathers and 

 cooling of the skin surface. 



There must be a considerable difference between the acuity of 

 vision in gulls. I am not prepared at the moment to discuss this 

 matter, but I have never been able to repeat an experiment I made 

 some years ago on the species — L. ridibundus^ I think — that is 

 abundant on the Lake of Geneva. During excursions to Ouchy and 

 other resorts along the lake shore it was my habit to carry with me 

 a bag of grapes with which to feed the gulls. Parenthetically, all 

 the gulls whose acquaintance I have made are very fond of grapes. 

 I soon found that they would hawk the fruit when thrown one by 

 one into the air. I then tried to find how small an object could be 

 seen and caught in midair by these birds — to discover that the 

 smallest grape in my collection when tossed into the air was re- 

 trieved before it reached the water. I have not been able to repeat 

 that little experiment with any of our western or California gulls. 



Referring once more to the black-headed gulls whose acquaintance 

 I cultivated at Ouchy nearly 20 years ago, they must not be mis- 

 taken for our black-headed or laughing gull {L. atricilla). Both 

 are quite common birds within their respective ranges, but the Swiss 

 species is much smaller and its plumage more charged with black 

 than the American variety. Perhaps I was among the first of those 

 to whom my former teacher in the London Hospital, Sir Frederick 

 Treves, refers in his charming book, " The Lake of Geneva," as 

 visitors "who have so persistently fed these (black-headed) gulls 

 that they are demoralized, and will shortly become, like the pigeons 

 of Venice, a company of tourist-supported idlers." 



As every mother knows, the color of her infant's eyes undergoes 

 changes, more or less marked, during the first year or two after 

 birth; but these alterations are negligible when compared with the 

 eyes of some birds. For example, the very pretty, and often very 

 tame, little red-billed gull (in New Zealand, the mackerel gull) or 

 Larus scopulinus, is born with dark-brown, almost black eyes, and 

 yet by the time it is a year old they have changed almost to a pure 

 M'hite. A similar alteration is noticeable in the iridic coloration of 

 the larger but equally beautiful southern black-backed gull {Larus 

 dominicanus) , that ranges the whole Southern Hemisphere. Both 

 these birds are easily domesticated ; they act as valuable scavengers, 

 and are devourers of caterpillars and other insect pests. It is inter- 

 esting to see them about Australasian harbors and fields, doing their 

 useful work, unafraid of man. 



