UN habliat 

 oiMiileHes 



OF YELLOWSTONE AND 



GRAND TETON NATIONAL PARKS 



By natural selection, variousspeciesof birds have adapted to life in a variety 

 of natural environments. Habitat requirements evolved over long periods 

 and were influenced by factors such as geographic isolation and availability 

 of food and cover. 



Habitat requirements vary with each species. Some species adapt to a wide 

 variety of environmental conditions, while other species have very specific 

 requirements. Natural communities or complexes are populated by species 

 occupying every available niche within the community. However, these 

 environmental complexes seldom have definite boundaries. Transitional 

 areas between these complexes often support a greater number and variety 

 of birds than their adjacent complexes. 



The ranges and habitats of birds are slowly, but continuously, undergoing 

 changes as a result of competition and interaction with other species and 

 other organisms (including man), natural succession and climatic changes. 

 More than 225 species of birds have been recorded in one or more of the 

 habitat complexes in Yellowstone and Grand Teton National Parks. The 

 following descriptions of bird habitat complexes was designed to serve as a 

 general guide to bird distribution in the two parks. 



