Illinois the knocked-down cripple loss is about 30 per cent of the number of ducks bagged, or 
about 9 per cent of the total population. It is known that at least a small proportion of these 
cripples recover; it is also known that, of the ducks shot at but apparently unharmed, many are 
Table 14.--Ratio of cripple loss to bag loss in ducks shot at private hunting clubs and 
at public shooting grounds in Illinois, 1938-1945. 
Number Crippled 
Ratio of Cripple Loss 
Place of Hunting Number Bagged to Bag Loss 
Private hunting clubs- 568 17.6:100 
369 18.2:100 
Public shooting 556 37.7:100 
Aer SS 612 40.5:100 
so severely wounded that they soon die. These two factors tend to counterbalance each other, 
and, in the absence of more detailed information, the cripple mortality rate used is that ob- 
tained by appraising the reports of hunters. The cripple loss of 9 per cent added to the pro- 
portion of mallards bagged, 32 per cent, brings the calculated total annual shooting losses of 
Mississippi flyway mallards up to 41 per cent of the population in the period 1939-1947. 
The annual mortality rate of five year-classes of mallard drakes banded as adults 
at Lake Chautauqua averaged about 40 per cent, table 2. The year-of-banding mortality rate 
for males banded as juveniles was about 55 per cent, table 1. Since age ratios of male mallards 
in the Mississippi flyway, 1939-1947, show that juveniles comprise about half of the male fall 
population, then the annual mortality loss in the male population would be about 48 per cent. 
The mortalities in the femalé population and the entire population would be somewhat higher. 
If shooting losses annually account for 41 per cent of the mallard population, and 
if the annual mortality is 48 per cent of this population, then natural losses would amount to 
only 7 per cent. Man is responsible for part of the losses usually classed as natural. Inves- 
tigations on lead poisoning of ducks by James S. Jordan and the senior author, both of the 
Natural History Survey, tentatively indicate that annually 6 per cent of the mallard population 
in the Mississippi flyway die from this cause. Thus, man appears to be directly or indirectly 
responsible for most of the yearly mortality losses among Mississippi flyway mallards. 
Our hunting-loss calculations have produced a maximum figure that is probably too 
high. An upward distortion in this figure could well have resulted from the high compensation 
figure (for non-report of bands) in deriving it. 
The black duck has relatively lower hunting losses but higher total annual mortality 
rates than the mallard. Calculations based upon the same crippling rate and the same band-re- 
turn rate for the black duck as for the mallard show that annual shooting losses for the black 
duck averaged about 34 per cent and natural losses about 20 per cent of this population. 
From duck species that undergo above-average shooting losses, we turn for com- 
parison of natural versus hunting losses in the blue-winged teal, a species that probably has 
smaller hunting losses than any other popular game duck. 
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