THE ORIZABA (IRQ UP 



A Study of the Influence of Altitude on the Distribution of 



Life 



FROM the dense tropical forests, at the base of Mount Orizaba in 

 Vera Cruz, Mexico, one may look upward toward the equally grand 

 forests of pines and spruces which, 10,000 feet higher, cover the 

 sides of the mountain. 



In the luxuriant vegetation are Parrots, Toucans, Trogons, Motmots, 

 and many other tropical birds; and from their home one may see the 

 zone where Crossbills, Evening Grosbeaks, Juncos, Brown Creepers, 

 and other boreal birds are nesting. Owing to differences in altitude, 

 which are the equivalent of differences in latitude, the three great Life 

 Zones which go to make up the fauna! regions of North America are 

 thus represented in this one group, which may be said to epitomize all 

 the other groups contained in this hall. 



The studies for this view of Mount Orizaba were made at Cordova 

 (altitude 3,500 feet), at the upper border of the Tropical Zone. The 

 primeval tropical forest having long since been cut off in this region, it 

 was necessary to descend to a level of about 1,000 feet, near Motzo- 

 rongo, to secure studies for the forest depicted. The accompanying 

 view of the Rio Blanca was also made near this point, from which Mount 

 Orizaba may be seen in the same relation in which it is here painted. 



The birds contained in this group are representative species of the 

 tropical portions of the State of Vera Cruz. They have been selected 

 to show the tropical character of the bird-life of this region, rather than 

 the bird-life of any particular part of it; and represent but a small part 

 of the avifauna of several hundred species. 



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