Year-of-banding recoveries of blue-winged teals ranged from 1.4 to 3.6 per cent, 
table 12, and averaged about 2.45 per cent. Since many band recoveries from shot ducks come 
from south of the United States, where the incentive to turn in bands is probably not so great as 
in the United States, the proportion of bands not reported is probably higher in the blue-winged 
teal than in the mallard. However, lacking specific data, we have used the same correcting 
factor as was used for the mallard--190 per cent. This brings the yearly hunter-bag of blue- 
winged teals up to about 7 per cent of the total population of this species. The calculated 
cripple loss, 30 per cent of the number of blue-wings bagged, or 2 per cent of the total popula- 
tion, would increase the total annual shooting loss to 9 per cent. 
The yearly mortality rates for the first 5 years following banding averaged about 57 
per cent for blue-wings, table 7. The shooting mortality accounted for only 9 per cent of the 
population, leaving 48 per cent of the blue-wings' annual mortality to be accounted for by 
natural causes. Although the shooting mortality rate is considerably lower in the blue-wing 
than in the mallard, the over-all mortality rate is higher in the teal. 
It seems significant that, although the shooting mortality rate is lower in the black 
duck and the blue-winged teal than in the mallard, the over-all mortality loss is greatest in the 
blue-winged teal, next so in the black duck, and least in the mallard. It is apparent that shoot- 
ing losses do not account for all the differences in mortality rates among the three species 
of ducks. 
Could the mallard ever have had an appreciably lower total mortality rate than it had 
for the period 1939-1947? No wild game bird species so far studied has such a low total mor- 
tality rate, even ring-necked pheasant populations, completely or partially protected. Song 
birds, much less productive than the mallard, have comparable annual mortality losses. 
What has enabled the mallard to undergo heavy shooting losses without suffering 
higher over-all mortality rates? 
Every wildlife population lives in an environment of limited carrying capacity. If 
hunters take the excess population, then the lower population density that results makes the re- 
maining individuals less subject to predation, disease, food shortages, and other factors that 
contribute to natural losses. 
It seems reasonable to us to assume that, in the mallard, heavy shooting losses 
have largely replaced natural losses that would otherwise have occurred to enable the popula- 
tion to live within the limitations of its environment. The mallard population has an internal 
elasticity that allows most of its components, including those that make up natural loss and 
shooting loss, considerable stretch or shrinkage. But the extent of stretch or shrinkage is 
limited, and the natural loss can never shrink to zero. Some natural loss must be expected, 
and the shooting loss cannot entirely replace the natural loss. 
The conjecture that game bird populations possess internal elasticity is substantiated 
by Bump et al. (1947), who found that although hunting took 17 per cent of the ruffed grouse fall 
population in New York study areas, the gun increased the total mortality rate by only about 8 
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