44 A NATURALIST ON DESERT ISLANDS. 



native of North America, and spends the winter " down 

 south." The point of interest about it is that in the Grand 

 Cayman, where we have found it fairly abundant in any 

 open grassy clearing, it is said to be resident and to 

 breed. Unfortunately, I made no notes on this pomt 

 with regard to the Swan Island bird, but I have a distinct 

 recollection of being told it remamed all the year. If 

 the suppositions in the case of either or both of these 

 islands prove correct, we have here a case of a migratory 

 bird not only extending its breeding area, but becoming 

 non-migratory, and we can see how easy it will be for these 

 insular birds, in the course of time and under changed 

 conditions of climate and food, to become differentiated 

 into new species or sub-species. 



Myrtle-warblers were the first birds we saw after 

 landing. They were flitting about in a clearing made for 

 the wireless telegraph station. We saw several other 

 flocks on the island, but always in similar clearings and 

 near the edges of the woods, and when disturbed they 

 immediately flew for safety to the trees. I am inclined 

 to think that this bird must be more of a seed-eater than 

 any of the large family of wood -warblers {Mniotiltidce) 

 to which it belongs. It can only be a recent addition to 

 the avifauna of Swan Island, for it is not hkely to have 

 been present when every inch of ground was covered 

 with thiok woods. So much, then, for doubtful residents. 



Of the rest of our list, the frigate-birds, and both gannets, 

 are undoubted residents, and we shall have some remarks 

 to make upon them in describing Little Swan Island. 

 No. 7, the little green bittern, also breeds here, and Mr. 

 Townsend considers it to be distinct from species foimd 

 elsewhere, in the West Indies, so that we are left with 

 only two to say anything about. These are the vitelline 

 warbler and the pigeon. 



It would be difficult to mistake any of these birds for 

 anything but residents or aborigines of long standing. 

 They are so tame that it is obvious they have lived 

 here for centuries untroubled, imtil quite recent times. 



