Flyway probably were higher than they should have been. True age 
ratios in the kill of these four species, therefore, probably were 
slightly lower for the mallard and considerably lower for the pintail. 
Canvasback age ratios are not comparable to those of the pintail and 
mallard because most of the canvasbacks in the sample were taken 
during migration. Stewart, Geis, and Evans (1958) found that early 
in migration, immature canvasbacks tended to be taken in relatively 
greater proportion than adults. Thus, the canvasback age ratio was 
biased more in favor of immatures than were the age ratios of other 
species that not only migrate through the Flyway but also winter 
there. Since the age ratios in shot samples are higher than the true 
ratios, because of the greater vulnerability of immatures, it is 
reasonable to conclude that redheads, mallards, canvasbacks, and 
pintails had very unsatisfactory production in 1959. 
A large part of the population of these species breeds in the 
southern prairie provinces, where there was a severe drought during 
the 1959 breeding seasono 
Among those species for which there were samples of 100 or more 
wings, the highest age ratios were for greater scaup, bufflehead, 
green-winged teal,and American widgeon. Since these species tend to 
be far-northern breeders, it seems likely that they experienced more 
normal conditions than the four species discussed above. 
The significance of the age ratios for the various species will 
be much greater when comparable data are available from future years. 
Mallard 
lo. Variation among States 
Mallard age ratios in the wing collection are shown in Table 33. 
Mallard age ratios differed among the States in a recognizable pattern. 
Age ratios in the top two tiers of Mississippi Flyway States increased 
steadily from west to east. Age ratios from west to east in the north- 
ern most tier of States were: Minnesota, 1.20 immatures per adult; 
Wisconsin 2.13; and Michigan 2.56. In the next tier of States, the 
series was: Iowa, 0.53; Illinois, 0.64; Indiana, 1.46; and Ohio, 1.55. 
In all other States of the Flyway, mallard age ratios were consistently 
low, approximately 0.5 immature per adult. It seems likely that 
differences in mallard age ratios among States reflected the extent 
to which the mallards harvested in each State were produced in drought- 
stricken portions of the breeding range. The States in the north and 
east tended to have higher age ratios than those in the west and south. 
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