November, 1^44 



Bellrose: Duck. Populations and Kill 



345 



Table 7. — Per cent of entire fall flight, per cent of total bag, and mortality quotient 

 (indicating relative mortality from hunters) for each of the important duck species 



or groups in the Illinois River valley, 1942. 



Species* 



Per Cent of 



Flight During 



Entire Fall 



Per Cent of 



Total 



Bag 



Mortality 

 Quotient 



Mallard and black duck 



Pintail 



Green-winged teal 



Blue-winged teal 



Widgeon 



Gadwall 



Shoveler 



Lesser scaup 



Ring-necked duck 



Canvasback 



Redhead 



Ruddy duck 



84.98 

 1.18 

 0.03 

 1.22 

 0.99 

 0.04 

 0.03 



10.14 

 0.55 

 0.47 

 0.01 

 0.36 



75.12 

 6.16 

 1.48 

 2.54 

 1.98 

 1.20 

 0.94 

 5.29 

 2.31 

 1.78 

 0.41 

 0.79 



0.88 

 5.22 



49.33 

 2.08 

 2.00 



30.00 



31.33 

 0.52 

 4.20 

 3.79 



41.00 

 2.19 



100.00 



100.00 



♦Certain species omitted because of lack of sufficient data. 



fowl season in 1942. This extension 

 in the season placed the mallard and 

 black duck under greater shooting 

 pressure in 1942 than in any other year 

 of this study, table 8. Other species 

 were not materially affected adversely 

 by the lengthened seasons, according 

 to the comparative data in table 8. 

 Whereas this table discloses an almost 

 uninterrupted rise in the shooting pres- 

 sure on mallards and black ducks during 

 the 5 years of this study, it indicates 

 that no such trend has occurred in other 

 species. 



As a group, diving ducks were under 

 more shooting pressure in recent open 



seasons than were dabbling ducks, 

 table 8. Figs. 10-15 disclose that most 

 of the diving ducks arrived after Octo- 

 ber 16, and that most of them departed 

 southward by December 16; thus, most 

 of the migration occurred during the 

 hunting season. 



There is comparatively little differ- 

 ence in the shooting pressure on most 

 species of diving ducks; as fig. 10 shows, 

 the species migrate at almost the same 

 time. Shooting pressure was unusually 

 high on the ruddy duck in 1938 and 1939 

 when the population was relatively low. 



Shooting pressure on most of the duck 

 species varied from year to year during 



Table 8. — Shooting pressure quotient for important Illinois River valley ducks, 1938- 

 1942; derived by comparing vulnerability quotient of species (5-year average) with 



mortality quotient for 5 separate years. 



♦Figures for ring-necked duck omitted, 1938 and 1939, and figures for redhead omitted, 1938-1942, because of 

 insignificant population and kill data. Figures for widgeon and gadwall for 1938-1940, calculated as explained in 

 text. 



