274 



Prof. S. F. Bairtl on the Distribution and 



Hirundo luiiifrons. 

 Turdus fiiscescens. 

 Protonotaria citrea. 

 Geothlypis Philadelphia. 

 Oporornis formosus. 

 Helminthophaga peregrina. 



Chrysomitris mexicanus. 

 Euspiza americana. 

 Guiraca ludoviciana. 

 Icterus spvirius. 

 — baltiuiore. 

 Qiiiscalus macrurus. 



One circumstance will attract our attention in examining these 

 lists of North American birds reaching the Isthmus of Panama 

 or passing beyond it as far as Bogota and into Ecuador — namely, 

 that they embrace absolutely none of the species characterizing 

 the middle province,, all belonging to the eastern. It would 

 seem to be the case that the migratory birds of the Rocky 

 Mountain region go only a comparatively short distance south- 

 ward into Mexico, few of them even reaching Guatemala, but 

 preponderating on the west coast. It has already been re- 

 marked that the birds strictly characteristic of the Pacific 

 region of the United States scarcely appear to go into Mexico 

 at all. 



While the number of land-birds reaching the gates of South 

 America, and passing through them, principally along the 

 Andes into central New Granada and Ecuador, is so small, the 

 case is very diflferent with the waders, a large proportion of which 

 are during our winter spread over the entire continent, almost 

 as far as Patagonia. Comparatively few, however, of the 

 Natatores follow them in this journey. 



The following list comprises the principal indications of the 

 winter visitors to the West Indies from the United States, all 

 of them, excepting Nephocoetes niger, belonging to the eastern 

 fauna. 



Other Islands. 



Cathartes aura 



atratus 



Falco anatum 



columbarius . . . . 



Buteo borealis 



pennsylvanicus . . 



Eostrhamus sociabilis 

 Circus budsonius . . . . 



*? 



