not aged as accurately as were other species, because the tertial 
feathers were missing from many of the wings. 
Blue-winged Teal 
Table 43 shows the regional variations in age ratios of blue- 
winged teal. In the northern tier of States there was a progressive 
increase in the age ratios in samples from Minnesota through Wisconsin 
and Michigan, in much the same manner as was observed for the mallard, 
except that age ratios generally were higher for the blue-winged teal 
than for the mallard. Presumably the reasons for the regional differ- 
ences are the same as for the mallard, i.e., blue-winged teals shot 
in Minnesota came from an area more adversely affected by drought 
than did those taken in Michigan. Samples from the second tier of 
States had an unweighted average ratio of 1.6 immatures per adult in 
contrast to 1.8 in samples from the northernmost tier. Since these 
are unweighted averages, the low ratio of the Minnesota sample received 
undue weight. The trwage ratio in the northern tier of States very 
probably was substantially higher than 1.8. Only 25 blue-winged teal 
wings were received from Missouri, Tennessee and Louisiana, of which 
23 came from Louisianas The age ratio was remarkably low, 0.1 immature 
per adult. Since the validity of the age criteria used to determine 
age of blue-winged teal from wings has not yet been established for 
birds collected late in the season, the great drop in the age ratio 
could mean that errors were made in the interpretation of the wings 
collected late in the-seasone Louisiana bag checks, however, also 
showed a very low age ratio, 0.08 immatures per adult. Only 15 imma- 
tures were found among 200 bluewings aged and sexed by cloacal exami- 
nation (Smith, 1960). This strongly suggests that the age determinations 
based on wings from bluewings taken late in the season were reliable. 
Age ratios in samples from Minnesota and Wisconsin were examined by 
time periods to see if changes occurred during the season (Table 44). 
In both States, age ratios on opening day were higher than they were 
during the remainder of the first week of the season. This tendency 
was more pronounced in Wisconsin than in Minnesota. After the first 
of the season, age ratios increased in both Minnesota and Wisconsine 
This is reasonable, since adult blue-winged teal, particularly males, 
apparently migrate earlier than immatures. Sample sizes after the 
first week were very small, howevere 
When blue-winged teal age ratios are compared with those of other 
species (Table 32) it should be realized that, because of the very 
distorted sex ratio among adult bluewings, the age ratio tends to be 
inflated. Apparently, a large proportion of the adult male bluewings 
migrate out of the United States before the hunting season begins, 
and hence do not appear in the hunting kill. This results in an 
-31- 
