estimate of relative recovery rate in 1962 
is too low because of inadequate and un¬ 
representative Canadian bandings that 
year. It is estimated, on the basis of 
banding stations in the United States (Ad¬ 
ministrative Report 46), that the actual 
relative recovery rate is probably be¬ 
tween 1.4 and 1. 8. If it is assumed that 
the actual rate is intermediate between 
these values (1. 6), the age composition 
of the mallard population was 0. 8 im¬ 
mature to adult in 1962 and 1. 0 im¬ 
mature to adult in 1963. This is a sub¬ 
stantial improvement but it still does not 
reflect a production ratio characteristic 
of a rapid rate of increase in the 
population. 
Black duck age ratios 
The observed black duck age ratios in 
the Atlantic Flyway kill were higher in 
1963 than in 1962. In 1962, there was an 
observed age ratio of 1.32 immatures to 
adult, while in 1963, it was 1.51. The 
highest age ratios were in the New Eng¬ 
land States and lowest in the southern 
part of the Flyway. 
In the Mississippi Flyway, there was 
a continued decrease in the age ratio in 
the black duck kill. The ratios declined 
from a high of 2. 04 in 1961, to the 
present low of 1.11 immatures to adult. 
There was a progressive decrease in age 
ratios from north to south among those 
States where estimates were made. The 
continental age ratio of black ducks 
showed little change from 1962 (table 
D-21). 
Adequate preseason banding data are 
essential in order to interpret black duck 
age ratios in the kill. As pointed out in 
Administrative Report 27, there is a 
strong suggestion that the annual vari¬ 
ation shown in the age composition of the 
kill in the past may have been caused by 
changes in differential vulnerability. 
Black duck preseason banding data are 
too meager to allow an estimate of the 
age composition of the population with any 
precision. Again, there is a suggestion 
that the improvement in the age ratio in 
the kill shown in the Atlantic Flyway was 
due, at least to some extent, to a change 
in differential vulnerability. Comparable 
banding stations in this Flyway indicate 
that the relative recovery rate in 1963 
was higher than that in 1962. Thus, the 
improved age ratios in the Atlantic Fly¬ 
way may reflect increase in the likelihood 
of immatures being shot rather than im¬ 
provement in the age composition of the 
preseason population. 
Blue-winged teal age ratios 
Because of the current interest in the 
blue-winged teal in the Mississippi and 
Central Flyways, only those two Flyways 
were tabulated. The other two Flyways 
were used only in the computation of 
weighted ratios for the entire United 
States. 
In the Mississippi Flyway, the ratio 
of immature to adult blue-winged teal in¬ 
creased 90 percent from 1962 to 1963 
(1. 65 to 3.13). The ratio of immatures 
to adults increased 153 percent in Min¬ 
nesota and 136 percent in Michigan. 
Age ratios are shown for those States 
in the Central Flyway from which a 
sample of 20 or more wings were ob¬ 
tained, The Flyway weighted average 
increased from 2.11 in 1962 to 2. 69 in 
1963. The combined weighted age ratio 
for the Mississippi and Central Flyways 
increased from 1. 24 in 1962 to 3. 04 in 
1963 (table D-22). 
The blue-winged teal and cinnamon 
teal could not be separated by wing char¬ 
acters and were combined for the purpose 
of calculating a continental weighted age 
ratio. The 1963 observed ratio in the 
continental kill was 2.41 immatures to 
adult as compared with 1.40 for 1962. 
This represents an increase of 72 
percent. 
Despite the large number of blue¬ 
winged teal banded preseason in 1963, 
recovery rates were so low that harvest 
rates for immatures and adults could not 
be measured with sufficient precision to 
accurately determine the age composition 
of the preseason population. For ex¬ 
ample, the pre season banding data sug¬ 
gest that immatures were over four 
times more likely to be taken than 
adults. This implies an age ratio in the 
34 
