1917.] Chapman, Distribution of Bird-life in Colombia. 5 



the origin of species and the distribution of life. It is also hoped that 

 the technical reports on our large collections may be acceptable to the 

 systematic ornithologist. 



Colombia was selected as our first field of operations, not because we 

 believed it to be zoologically the least known part of South America. On 

 the contrary, so far as birds are concerned, the trade in native-made, 

 'Bogota skins' has doubtless resulted in a greater number of specimens 

 being shipped from Colombia than from any other part of South America. 



Colombia was chosen, therefore, because of its proximity, because cir- 

 cumstances ' had already aroused our interest in its avifauna, because lying 

 at the base of the Isthmus of Panama it is also at the. crux of the problem 

 of intercontinental relationships, and because it possesses more diverse 

 physiographic and climatic conditions, combined with a greater variety 

 of animal life, than any other part of South America of similar extent. 



The intensely humid Pacific, and arid Caribbean coasts, isolated Cauca 

 and upper Magdalena Valleys, widespreading Amazonian forests and no 

 less extensive llanos, three distinct mountain ranges and insular mountain 

 mass of Santa Marta, each with four zones of life, give exceptionally wide 

 scope for the manifestation of biogeographic phenomena in Colombia. 



From December, 1910, to April, 1915, we have had from one to six 

 collectors in Colombia, crossing and recrossing the mountains and travers- 

 ing the intervening valleys in pursuance of a carefully planned survey, 

 designed to extend from sea-level to snow-line, and from the Pacific coast 

 to the tributaries of the Amazon and Orinoco. 



At the outset we were impressed by the absolute necessity of determining 

 the level, as it were, at which a species flows before we could hope to dis- 

 cover whence it came and whither it is going. 



A study of the distributional problems presented by Colombian bird- 

 life, based on a collection of specimens from unknown altitudes, would lead 

 to as inaccurate and confusing results as would the study of a collection of 

 fossils from unknown geological formations. 



The differences between the bird-life of the Tropical and Temperate 

 Zones, for example, are equally important whether occasioned by latitude 

 or altitude. No one would think of removing the labels from specimens 

 collected on the Amazon and in Argentina and then writing of them as 

 having all been taken at one locality. But it would be no more improper 

 to do this than to write of the distribution of bird-life in the Eastern 

 Andes of Colombia on the basis of a collection of native-made 'Bogota' 

 skins. 



As a result of our labors, we are now in possession of approximately 

 15,775 birds and 1600 mammals, all carefully labeled with locality and 



