Sex Ratios in Pigeons. 
467 
liable to perish.” Cuenot (1899, p. 491) is the only author we have 
found who gives any actual data on this point. He states that while 
there may be some truth in the assertion it certainly is not general, 
for he examined two young pigeons which were less vigorous than 
their mates, and which the breeder assured him for that reason were 
females; in reality one was a female, but the other was a male. In 
another case he dissected two squabs from the same nest, one of which 
was very vigorous and should have been a male, the other was less 
developed, and therefore should have been a female; but this time 
both were females. 
On this point we have 60 cases to report. These records were 
made at Wisconsin by Mr. F. J. Kelley, who has kindly tabulated 
them for us. They show the relation of sex to the relative size of the 
two squabs at the time of banding, which means at the age of 10 to 
15 days. The cases recorded include only those in which there was a 
fairly well-marked difference in size, and in which the squabs had 
remained in the same nest and under the same conditions so far as 
could be told. The data may be summarized as follows: 
Larger squab cf, smaller squab 9.23 cases. 
cc 
CC 
9, 
CC 
cc 
d. 
. 4 
cases. 
a 
cc 
d, 
CC 
cc 
d . 
.13 
cases. 
cc 
cc 
9, 
cc 
cc 
9.. 
.16 
cases. 
CC 
cc 
Unknown, 
cc 
cc 
cf. 
. 2 
cases. 
CC 
cc 
CC 
cc 
cc 
9. 
. 1 
case. 
cc 
cc 
9) 
cc 
cc 
Unknown.. 
. .1 
case. 
Total sexes- 
-large squab 
— 
36 d'd 
I 
21 99 
small squab 
— 
19 dd 
• 
40 99 
55 d'd : 61 99 
These data certainly seem to lend considerable support to the 
idea that the larger squabs are in a significant majority of the cases 
males. A consideration of cases in which one squab died before 
banding shows less striking results. The argument in this case 
would be that the female squabs are smaller and less vigorous, more 
