Carriker : List of the Birds of Costa Rica. 327 



On the Pacific coast the same phenomenon is observed among some 

 of the above-mentioned species and others nearly related, but just 

 what these are, I was never able to learn positively, not having the 

 opportunity of collecting in that region at the time of the ripening of 

 the fruit which is said to attract them in large numbers. 



On the Habits of North American Winter Visitors. 



. Strange as it may seem, the North American migrants, upon their 

 arrival in Costa Rica, distribute themselves in a most unaccountable 

 manner. Myiochanes virens and M. richardsoni are to be met with 

 almost anywhere from sea-level up to 9,000 or 10,000 feet on the 

 Volcanoes de Irazu and Turrialba. On the other hand, Nuttallornis 

 is seldom seen below 5,000 or 6,000 feet, and is most abundant 

 between 8,000 and 10,000 feet. Empidonax flaviventris and E. 

 trailli range from sea-level up to 3,500 feet. At least one of the 

 Mniotiltidce, Wilsonia pusilla, is found from near sea-level to timber- 

 line, others from the lowlands up to 4,000 or 5,000 feet, while some 

 are only seen on the central plateau. Guiraca ccerulea seems to be 

 confined almost entirely to the Pacific lowlands. Zamelodia ludo- 

 viciana has only been recorded from the Caribbean slope and central 

 plateau, while Spiza americana ranges from ocean to ocean, up to 

 4,000 or 5,000 feet. Passerina cyanea seems confined to the high- 

 lands. Ducks, some shore-birds, and herons are found at all altitudes, 

 where suitable conditions are to be met with. 



One would naturally look for Nuttallornis borealis at a high altitude, 

 it being a bird of the Canadian fauna, but why should Myiochanes 

 range from sea-level to 9,000 feet, or why should Empidonax flavi- 

 ventris and E. trailli be found in the Humid-Tropic and Sub-Tropic 

 Zones, when they breed over practically the same territory as Nuttal- 

 lornis ? Perhaps by an exhaustive study of the food of these birds both 

 in their breeding haunts and in their winter ranges, a reason might be 

 found for this peculiar distribution, or perhaps it is only another of 

 those inexplicable problems so often met with. 



The migrants in their winter haunts are usually found in localities 

 having the same general character as those which they frequent in the 

 north. Their habits, too, are quite similar, with the exception that 

 they are almost invariably as silent as so many shadows. Never to my 

 recollection have I ever heard a migrant attempt a song, while but few 

 go as far as uttering a feeble chirp, with the exception of Icterus gal- 



