November, 1944 



Bellrose: Duck Populations and Kill 



359 



expression was that the half hour before 

 sunrise shooting was very detrimental 

 to hunting. 



Some hunters who expressed a prefer- 

 ence for shooting hours of sunrise to 

 sunset explained that waterfowl oc- 

 curred on their property only at sunrise 

 and sunset. The principal reason ad- 

 vanced by hunters for ending shooting 

 daily at 4 p.m., C.S.T., was that it kept 

 waterfowl from being "burned out" of 

 a region. 



Have longer shooting hours resulted 

 in a greater kill of waterfowl ? Shooting 

 hour regulations are difficult to evaluate 

 because of the influence of such other 

 variables as length of season, population, 

 weather and food conditions. Length 

 of seasons has changed with shooting 

 hours; so in order to reduce the influence 

 of varying lengths of seasons, as well as 

 variations in the duck flight, the per- 

 centage of the 5-year duck population 

 present during the open season of each 

 year has been compared with the per- 

 centage of the 5-year kill, table 10, to 

 give an index of the shooting pressure 

 resulting from various shooting hours. 



The highest index numbers indicate the 

 greatest shooting pressure and kill. 



Because of better hunting conditions 

 in certain years than in others the data 

 are inconsistent, but they show no evi- 

 dence that larger kills were made in 

 seasons of sunrise or sunset shooting 

 than in seasons of shorter shooting 

 days. The index figure for 1940, when 

 sunrise shooting was permitted, was the 

 same as for 1939, with 7 a.m. shooting, 

 table 10. In 1941 and 1942, with sun- 

 rise shooting, the shooting pressure, a 

 measure of the comparative kill, was 

 actually less than that with 7 a.m., 

 C.S.T., shooting in 1938 and 1939. 



Effect of Bag Limit 



In recent years, several biologists 

 have questioned the value of bag limit 

 as an effective measure jn restricting 

 the total 'game kill. 



Fig. 22, based on data assembled by 

 Dr. Yeatter and Dr. Thompson, shows 

 for most years from 1885 through 1938 

 the average daily bag of Duck Island 

 Preserve members and the observed bag 



50 



45 



40 



NO LEGAL BAG LIMIT 



tr 35 



iij 



30 



25 



20 



10 





r 



o> 



LIMIT 



1885 1890 



1895 



1900 



1905 



1910 



1915 



Fig. 22.— Average daily duck bag made by members of the Duck Island Preserve near Ban- 

 ner, Illinois, during certain periods from 1885 through 1938 in relation to the bag Hmit ob- 

 served by the club. 



