10 BIRDS OF SOUTHWESTERN MEXICO. 



" Icterus mesomelas. 

 " Psilorhinus morio. 

 " Momotus lessoni. 

 " Trogon caligatus. 

 " Piaya cay ana. 

 " Conurus aztec. 

 " Chrysotis autumnalis. 

 " Ortalida vetula. 

 " Ortyx pectoralis. 



" Icterus pectoralis. 

 " Calocitta formosa. 

 " Mofnotus mexicanus. 

 " Trogon citreolus. 

 " Piaya mexicana. 

 " Conurus petzi. 

 " Chrysotis finscM. 

 " Ortalida poliocepliala. 

 " Ortyx coyolcos. 



" The preceding remarks apply exclusively to indigenous species. It 

 would be interesting if 1 could record here some facts relative to the 

 distribution of the species which reside in the isthmus in the winter- 

 season, or only during their flight; but this study would require several 

 years of continued observations which were made simultaneously on 

 both coasts. This part of Mexico is, moreover, less favorable than any 

 other for observations of this kind. The shrinking of the continent, the 

 absence of natural barriers, there make the dispersion of traveling-birds, 

 from east to west and vice versa, very easy. Another cause, which must 

 bring several migratory species on the shores of the Gulf of Tehuantepec 

 in winter, is the prevalence of northeast winds in the isthmus. These 

 winds, which blow there with extreme violence from the month of Octo- 

 ber, undoubtedly force a large number of birds that are traveling along 

 the Atlantic shore toward Central America to swerve from this line, 

 and push them toward the opposite coast. An analogous cause, the 

 prevalence of southeast winds from the month of March, that is to say, 

 that the time that the emigrant species return to the north, operates 

 with an inverse action, by bringing the species coming from the south 

 along the eastern shore toward the coasts of the Gulf of Mexico. 1 will 

 limit myself to state here the presence in winter of Dendrceca gracice in 

 the mountains of Tehuantepec, and the extraordinary abundance at the 

 same time of Chondestes grammaca and Euspiza americana on the plains 

 of the Pacific. 



" The shores of the Gulf of Tehuantepec, or, to speak more properly, 

 those of the salt-lakes communicating with the ocean, which extend 

 from Ventosa nearly to Tonala, are inhabited by a great number of 

 aquatic birds. Although belonging, for the most part, to northern spe- 

 cies, it is probable that a large number of them make their nests there. 

 I have found there in August, a time when the migratory birds have not 



