472 
Bulletin No. 162.—1915. 
In more than half the cases enumerated above, the surviving 
member of each pair of squabs failed to reach maturity; since both 
therefore died before six months of age, they in no way influenced the 
sex proportions in Group D. Summarizing those cases in which one 
member of the bisexual pair of nestlings died before six months and 
the other exceeded that period we find a total of 68 examples, — 31 in 
which the male died and the female survived, 37 in which the female 
died and the male attained the adult stage. While the number of 
female deaths in Groups A, B and C is here somewhat larger, it should 
be borne in mind that the number of cases is relatively small, and 
that we are dealing only with bisexual broods which happened to meet 
these conditions. So far as the above figures go, therefore, they seem 
to show that there is no marked tendency for one sex to be weaker than 
the other in bisexual broods, and there is only slight indication that 
male survivors may exceed female survivors in reaching the adult 
stage as here defined. 
Table 1 .- —Composition of population and number of deaths with respect to sex in the 
different age periods. 
Age period. 
Population. 
Deaths. 
Per cent, of 
population 
which died. 
Ratio of 
(ff deaths 
to 100 9 
deaths. 
dd 
$9 
C 3d : 100 9 ? 
dd 
99 
dd 
99 
A. 
866 
810 
106.9 
115 
114 
13.3 
14.1 
100.9 
r?. 
751 
690 
107.9 
228 
193 
30.4 
27.7 
118.1 
c. 
523 
503 
105.0 
135 
142 
25.8 
28.2 
95.1. 
D . 
388 
361 
107.5 
388* 
361* 
100.0 
100.0 
107.5 
The distribution of deaths with respect to age and sex (using 
the age-groups which have been defined) is shown in Table I, the 
♦This doc? not mean that all these birds were yet dead at the time of tabulation, but when their 
death occurs it will of course be in this period. 
