11. On the Upper Mississippi Refuge, it required an average 
of 3.94 hours of hunting per duck bagged, while near the Gardner 
Unit of Mark Twain, it required 7.35 hours of hunting per duck. 
For the entire area, an average of 4.95 hours of hunting was re- 
quired per duck bagged. 
12. Mallards comprised the bulk of the kill over the entire 
area checked, ranging from 40.30% of the checked kill on the 
Upper Mississippi Refuge to 95.21% near the Louisa Unit of Mark 
Twain. For the entire area mallards accounted for 62.90% of the 
checked kill. Most of the blue-winged teal and wood duck harvest 
occurs during the first few weeks of the season; other species are 
harvested quite uniformly throughout the season, except that 
goldeneyes and scoters show up in the late part of the season. 
13. A table of vulnerability was worked out for hunting 
conditions found in the area under study. Mallards, which were 
present in nearly the same percentage in the population and the 
checked kill, were assigned a rating of 1, and all other species 
were compared to this. 
14. Crippling loss varied from 25.27% near Keithsburg Unit 
to a loss of 6.34% near Gardner Unit. The Upper Mississippi 
Refuge averaged a loss of 20.94%. The overall average was 15.37%. 
There was some correlation between the hours required per duck 
and the crippling loss; that is, where more time was required per 
duck, the crippling loss was lower, and where fewer hours were 
required per duck bagged, the crippling loss was higher. This 
may reflect the effort expended to recover birds knocked down, 
the number of opportunities for crippling, or the type of hunting 
cover. 
15. The average annual kill from the area checked was 
203,815 ducks (including crippling loss). The average actual 
bag was 165,190 ducks per year, and the average crippling loss 
was 38,625 ducks per year. 
16. Although mallards constitute the bulk of the kill with 
an average kill in excess of 100,000 birds, there are 19 species 
of ducks commonly harvested along the Mississippi River. 
17. Presunrise hunting was twice as effective per unit of 
time as was later shooting. Presunrise crippling was 43% higher 
per unit of time than in later shooting, but the rate of crippling 
was actually less because of the greater number of birds taken 3 
during the presunrise period. _ 
18. Of the 251,876 hunters checked over the 15-year period, 
45.31% failed to bag game on the day they were checked, 10.44% 
succeeded in taking four or more ducks (depending on limit), 
17.72% succeeded in taking three or more ducks, 30.03% took two 
or more, and 24.66% took a single duck. 
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