Sex Ratios in Pigeons. 
507 
Summary, 
Below are summarized the principal conclusions of the present 
report. Although some of them may here be stated in a rather 
general form, it is to be kept in mind that they are based wholly 
on the data which have been presented, and no claim is made for 
their generality beyond this. Nevertheless it is our opinion that 
they are built on a broad enough foundation to render very probable 
their general application to domestic pigeons. 
Sex ratio. 
1. The normal ratio of the sexes of pigeons hatched is 105 males 
to 100 females (p. 465). 
Death rate. 
2. The death rate of squabs is especially high for the first two 
or three days after hatching, and at about 10 to 15 days of age 
(p. 470). 
Differential mortality. 
3. When the two squabs are of distinctly different size before 
the banding age (10 to 15 days) the larger squab is more often a male 
than a female (p. 467). 
4. The death rate for the two sexes, in bisexual broods, is essen¬ 
tially equal (p. 471). 
5. There is no marked tendency for one sex to be weaker than 
the other in bisexual broods, and there is only a slight indication that 
more males than females from such broods survive to adult life— 
placed at 6 months (p. 472). 
6. A consideration of the ratio of males to females in each of the 
age groups defined does not indicate a high relative mortality of 
i 
females in the ages preceding the adult state (p. 473). 
7. There is a high mortality of both sexes during the first two 
or three years of their adult life, and this is especially high in the 
females between the ages of one and two years (p. 476). 
