November^ 1944 



Bellrose: Duck Populations and Kill 



349 



-80 



-60 

 -40 

 -20 



WATERFOWL 

 CENSUS 

 ILLINOIS RIVER 



1941 



NO CENSUS 



T 



AUGUST 'SEPTEMBER 



OCTOBER ' NOVEMBER DECEMBER 



JANUARY 



Fig. 14. — Polygons, based upon number of birds per acre of water surface in the Illinois 

 River valley in 1941, showing the chronology of flight of 12 species of waterfowl in relation to 

 the hunting season. 



