Ch. 3— Wetland Values and the Importance of Wetlands to Man • 53 



Figure 5.— General Pattern of Duck Distribution in North America 



SOURCE: M. Wellef, Freshwater Marshes: Ecology and Wildlife Managemenf (Minneapolis, Minn.: University of Minnesota Press, 

 1981). 



dicated on figure 5, are coastal saltwater and fresh- 

 water tidal marshes, inland freshwater marshes, and 

 bottom land hardwoods that are used as overwinter- 

 ing and stopover areas by migratory waterfowl dur- 

 ing their biannual migrations (33). Shrub swamps 

 are used only to a limited extent by waterfowl, and 

 bogs and mangroves are used only sparsely (81). 



While diets vary with any species and locality, 

 depending on food preferences, availability, and 

 the time of year, wedand vegetation generally com- 

 prises a significant component of the diet of ducks, 

 geese, and swans. A major distinction between feed- 

 ing habits can be drawn between "dabbling," or 

 surface, ducks and "diving" ducks, or pochards. 



