8. sex ratios: A normal sex ratio is one in which the 
number of males and females is approximately equal. Species which 
are monogamous must have a normal sex ratio if they are to produce 
offspring with greatest efficiency. Wild ducks are believed to be 
monogamous. The sex ratio in most species of ducks is known to be 
more or less unbalanced in favor of the male. While the effects of 
an abnormal sex ratio are unknown, it is logical to assume that such 
@ condition is unhealthful to the species. 
To manage waterfowl successfully, we must learn (1) the 
sex ratio in the various waterfowl species and (2), if this ratio is 
abnormal, how the condition can be correctcd. 
Our 19S8" findings in one species, the malltard, are given 
jm table 5. 
HAbpLe S.—-—Sex ratio, in mallerds, Illinois Valley, 1958. 
Number Inspected PermiCent 
Period Drakes Hens Drakes 
October 15-31 lah B2 48 
November 1-15 68 69 50 
November 16-28 _ LOS « der 62 
Total 541 269 56 
Let ues suppose that 1b is desirable Go lcorreet i nemsiex 
ratio in mallards. It will be noted in table 5 that there was an 
excess of hens over drakes early in the season and that the opposite 
was true late in the season. Perhaps a later hunting season would 
tena to discriminate against males, thereby helping to balance the 
Sen) ratio. 
go. Weights; The belief has sometimes been expressed that, 
Since the cessation of legal baiting, ducks passing through Illinois 
are in danger of starvation. We examined over 2,000 ducks in 1938 
and found that only ducks with shot wounds showed signs of starva- 
tion. Most of the lightweight ducks were found to be late-hatched 
fuvenites. Their lack of weight could not be attributed to scarcity 
of food; they were merely light-framed individuals. A summary of 
mallard weights taken in 1938 is given in table 6. 
