508 
Bulletin No. 102. — 1915. 
8. The higher mortality of females at early adult ages, together 
with the higher proportion of males hatched (105 : 100), may be 
in large part responsible for the prevailing notion of a considerable 
excess of male pigeons in adult populations and seems to furnish 
real substantiation for this notion. The fact that males are generally 
more easily recognized than females probably adds to this impression 
(p. 477). 
Ratio of bisexual to unisexual broods. 
9. The number of unisexual broods, in which the squabs are either 
both male or both female, somewhat exceeds in our records the bisexual 
broods (one squab of each sex), but the odds against the numbers 
obtained representing a potential equality are very slight. These 
facts are directly contradictory to the statements that the two eggs 
usually produce a male and a female squab (p. 487). 
10. Considering only the unisexual broods, the number of “both 
males” to ‘‘both females” is practically equal (p. 487). 
Sex with respect to order of laying. 
11. A comparison of the numbers of each sex hatched from first 
eggs and from second eggs respectively, shows no tendency for the 
former to produce exclusively males and the later females, but as 
a matter of fact more males than females are hatched from both 
(p. 487). 
Time of laying. 
12. The mean time of laying of the first egg is about 5 P. M., and 
of the second egg about one o’clock of the afternoon of the second 
day following (p. 489). 
13. The mean interval between the laying of the two eggs is 
practically 44 hours (p. 490). 
14. The mean time between the laying of the first and second 
eggs decreases progressively in the months from February to July, 
inclusive (p. 491). 
