BIRDS THE WORLD OVER 



Introduction 



The exhibits in the Hall of Habitat Groups of Birds (Hall 20) repre- 

 sent birds in their natural surroundings. In some groups attention is 

 focused on a single species, as in the group showing the golden eagle and 

 its nest; in others the scene presents the birds that frequent a particular 

 kind of country, as in the group showing the birds of a marsh in the 

 neighborhood of Chicago. What the observer sees, as he looks into an 

 exhibit, is what he would see if he were in the field at the locality repre- 

 sented, and were fortunate enough to be there at exactly the right time. 



Walking through the hall is like embarking on a journey by magic 

 carpet, travelling from continent to continent and visiting desert, moun- 

 tain, and forest. The birds one sees are the realistic products of the 

 taxidermist's treatment of skins and feathers; the habitat includes the 

 accessories — the leaves, branches, grass, and earth in the foreground, 

 which may be in part artificial, and the painted background. Studies 

 have usually been made and material collected on the spot, and the 

 whole is as true to life as the scientist and the artist can make it. 



Kinds of birds differ from place to place, but birds are not spread 

 haphazardly over the globe. The ranges of the diff'erent species, and the 

 genera into which they are grouped, and the families into which the 

 genera are grouped, present definite patterns when drawn on a map. 

 These patterns are mainly in accord with present-day geography, but 

 are influenced by past geological changes and differences of climate and 

 vegetation. 



Birds probably originated in the warmer parts of the globe, some time 

 before the end of the Jurassic Period, 155,000,000 years ago. As they 

 evolved and differentiated, they spread over most of the world and be- 

 came adapted to local conditions. This was and is a continuing process, 

 part of the whole process of evolution. Land birds, for instance, reached 

 some areas by land connections, over such bridges as that which crossed 



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