Table 1. Sample counts on the sex-ratio of pintails in post-breeding season 
gatherings at Delta, 1950 
. 
al 
? 
~ 
1 
* 
b 


Percentage 
Date Drakes Hens of hens 
June 13 52 24 . 32 
14 68 19 22 
15 60 : 18 23 
16 73 : 26 26 
19 70 20 22 
20 93 26 22 
23 104 ,, 34 25 
= ee ee SS 
Total ’ 520. 167 _ Av. 24 
Conclusions 
From the graphs in Figure l, it is apparent that mallards and pintails began 
nesting in 1949 during the week of April 15-21 but that in 1950 they began about two 
weeks later. There is some indication that in these two species the season was extended 
at the end by approximately the amount it was delayed at the beginning. 
In the case of the blue-winged teal, a later nesting species, the delay was one 
week only. With this bird the season was apparently extended the amount it was delayed. 
Thus it would appear from these data that for the Delta region the lateness of 
the season did not seriously reduce nesting opportunity. For these early and compar- 
atively rapid-developing species the season was not so late that large numbers of young 
would be unable to fly at freeze-up time. 
For adult hens which have to moult after the young are grown, however, it 
may mean a moulting period so short that they will not have time to grow new primaries. 
Large numbers of pintail hens were seen in mixed gatherings just as the 
nesting season came to a close (as determined in Figure 1). Sample counts on one area 
showed that from seven counts, 24 percent of the birds were hens. These hens were 
apparently unsuccessful nesters who were no longer trying to renest, as all successful 
hens should be with broods or on nests. 
