408 Wetmore, Birds of Vieques Island, P. R. [oct. 



passage to the larger island. This same strait, though only from 

 6 to 1 1 fathoms deep, is a barrier to fifteen of the Greater iVntillean 

 forms found on Porto Rico, while of the nine forms that do cross 

 three are of uncertain status as bona fide species for Vieques Island. 



Migration. 



Two of the breeding birds of the island are migratory, viz., 

 Progne dominieensis, and Vireosyha c. calidris. A third, Elainea 

 w. viartinica is believed to be only a summer visitant not a resident. 

 The first two probably arrive in February; the last was not noted 

 until March 25, 1912. 



Among the North American migrant Warblers there was almost 

 constant movement during my visit. These birds always seemed 

 restless and a diurnal migration from east to west along the length 

 of the island was noticed. On March 19, March 27, and again on 

 April 2 true weaves of migration occurred and these birds were 

 exceptionally common and active. Parula and Prairie Warblers, 

 Ovenbirds, Redstarts and Black and White Warblers were all 

 affected in this movement. In each case the bulk of these birds 

 disappeared at once and they were present in their usual numbers 

 during the following days. Vieques Island forms a stepping stone 

 for the individuals that winter in the Lesser Antilles, in their 

 vernal and autumnal flights and many interesting observations 

 might be made here by a resident ornithologist. Many species 

 may be added to the migrants given in the following list, especially 

 among the shorebirds and warblers and stragglers are to be ex- 

 pected in all groups. 



Bibliography. 



In the following books and papers are found the more important refer- 

 ences to the avifauna of Vieques Island. I am indebted to Dr. C. W. 

 Richmond for certain manuscript notes made during the course of his work 

 on the island. 



BOWDISH, B. S. 



1900. Some winter birds of the Island of Vieques. Oologist, XVII, 

 May, 1900, 71-74. 



