In ducks the parent-child relationships are short, and family traditions are thus weak. 



Redhead ducklings, such as these, are often abandoned by the 



mother several weeks before they can fly. 



the young mature later in the summer, thus enjoying a shorter period of 

 breeding-ground experience their first year. Moreover, they are much less 

 tolerant of variations in the nesting cover, and they do not pioneer into a 

 region for several years because of the slower development of a suitable 

 habitat. When water comes to the dry prairies of Saskatchewan, or when a 

 new lake is established, Mallards and some other river ducks are often there 

 as nesters the very next year, but the arrival of the diving ducks is delayed 

 until their nesting cover has become established. In 1945 the surface water 

 remained on the farmlands of the Portage Plains and Red River Valley 

 through the spring and summer for the first time in at least a decade. Mal- 

 lards and Pintails and, less frequently, Shovellers and Blue-winged Teal 

 settled down on these areas, and breeding pairs were scattered over country 

 that had seen no nesting ducks for several waterfowl generations. None of 

 the diving ducks moved to these new waters, which were lacking in emer- 

 gent vegetation. In the same way, large numbers of Pintails invaded south- 

 western Saskatchewan, where there was an abundance of new water in the 

 spring of 1952 (Gollop, Lynch, and Hyska, 1952). Bue, Blankenship, and 

 Marshall (1952) have shown how the waterfowl advanced to occupy the 

 new stock-watering ponds of western South Dakota. In such range exten- 



229 



