458 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 56. 



the back are pearly white, and not pure white as in the larger species. 

 As I observed it this species was wilder, being found more commonly 

 about outlying rocks, while the dominicanus is the familiar visitant 

 of the beaches and fishing camps. The foUow^ing notes refer to Lams 

 dominicanus. 



LARUS DOMINICANUS Lichtensteln. 



THE GAVIOTA. 



The gaviota, or Dominican gull, is so generally distributed over 

 southern seas and so familiar to travelers and seamen that one hesi- 

 tates to imagine that the observations of any but the most experienced 

 ornithologist could add to existmg knowledge regarding it. Never- 

 theless, to exclude the gaviota from the present account would be to 

 leave the picture of bird-life upon the islands too incomplete, and to 

 ignore a most significant element in the bionomics of the bird com- 

 munities. 



Though not equaling most of the other birds of the islands in 

 abundance,value, or interest, the gaviotas form an important element 

 in the aesthetic effect and keep one most insistently reminded of their 

 presence (pi. 55). They frequently follov/ one about, circling slowly 

 over-head and uttering harsh cries. They manifest a greater diversity 

 of habit than any other of the familiar sea birds. Though not 

 strictly gi-egarious, they are often seen in flocks of some hundreds, 

 resting drowsily on some interior flat of guano or sand and appearing 

 like gTOups of white baUs on a dark background. More often they 

 are seen isolated or in groups on some slope commanding a view of 

 the water. Favorite positions are on salient points of the shore or 

 smaU outlying rocks projecting. a little above water. Again they are 

 found far away from the islands, floating on the waves or flying slowly 

 after a vessel watching for offal. 



The gaviotas make four or five different calls: the familiar caw, caw, 

 in flight; the prolonged laugh, ha-ha, ha-ha, ha-ha, ha-ha., ha (or 

 cah-cah), when standing; a softer and shorter ca, ca, ca, ca, (like ca 

 in ''call") repeated rapidly and staccato while flying; and a sort of 

 clucking sound when at rest. 



Near the large fishing camp at Lobos de Tierra, large numbers of 

 the gaviotas regularly congregate to feed on the waste matter at the 

 camp. It was repeatedly observed that while the birds would feed 

 even between the feet of the native fishermen they would fly quickly 

 at the approach of a white stranger. 



Gaviotas are not only scavengers of the beaches and rookeries, 

 but are most pernicious in their depredations upon the nests of other 

 birds. I have seen them taking the eggs and fledglings from the 

 nests of pelicans and piqueros, and even robbing eggs from other 

 gaviotas. They break the eggs at the nest or take them into the air 

 and let them fall to break on the rocky groimd. They will swaUow 



