north of the Wisconsin River, while it becomes progressively 
less further down river. Thus, crippling -loss is probably also 
related to comparative density of cover in the areas being hunted, 
for heavy cover makes recovery of downed birds more difficult. 
In many areas of Mark Twain Refuge, blinds are situated where 
ducks knocked down fall into open water making recovery relatively 
easy. 
A comparison of crippling loss by area and year is shown in 
table 27. 
Estimated total kill by hunting 
Over the past 7 years an average of 203,815 ducks have been 
killed each year on the areas checked. This figure includes 
birds brought to bag as well as those lost as cripples. The 
Upper Mississippi Refuge alone averages a kill of 153,475 ducks 
each year, including 121,050 bagged and 32,425 lost as cripples. 
Table 28 shows the 7-year average figure of birds killed by area 
checked. 
Table 28 - Average Annual Kill 
Average annual Average annual AVERAGE ANNUAL 

Area bagged crippling loss TOTAL KILL 
Upper Mississippi 121,050 32 ,4e5 153,475 
Equa 8,640 1,290 9,930 
Keithsburg 2 ,895 980 3,875 
Gardner 2,360 160 2,520 
Batchtown 14,110 1,880 15,990 
Calhoun 16,135 1,890 18 ,025 
AVERAGE . 
ANNUAL KILL 165 ,190 38 ,625 203,815 

Total kill (bagged plus cripples) for each area checked, by 
year, is shown in table 29. (Table 30 shows average annual harvest, 
by species, for each area checked.) 
Presunrise data 
There has been much speculation as to the effect of this addi- 
tional half-hour of shooting, both as to hunting success and 
43 
