Figure 12 — Over half of the original wetlands in the United States have been converted to agriculture and 

 other uses. 



ment such as urbanization has also displaced native connmunities. The net result of 

 both extensive and intensive land development is that species least adaptable or 

 unable to adapt to these changes (e.g., large predators and forest interior birds) have 

 become restricted in their distribution. The loss of natural habitats is one of the 

 primary causes of both modern extinctions and endangerment of species. 



— During the past century, 40 taxa of North American fish have become extinct, 19 

 of them since 1964. 



— Seven species and subspecies were removed from the Federal endangered and 

 threatened species list in the last 10 years because of extinction. 



— Over 200 species and subspecies are no longer being considered for Federal 

 protection because they are believed to be extinct. 



— Data on trends in species populations indicate that there are significant numbers 

 of species with declining populations. For example, ducks, forest interior birds, 

 and Pacific salmonids are exhibiting long-term declines. 



— Wildlife management has resulted in numerous successful population 

 recoveries, including deer, elk, pronghorn, Canada goose, and wild turkey. 



— Colonial wading birds (e.g., egrets and herons) have made substantial 

 population recoveries since the beginning of the century. 



17 



