Sex Ratios in Pigeons. 
481 
at the time of fertilization of the egg. Furthermore, it is difficult 
to conceive by what sort of mechanism a relationship of this sort 
could be effected, especially when we consider the irregularities which 
may occur in the egg laying of the pigeon. While it is true that they 
ordinarily lay two eggs at each nesting, it is not at all uncommon among 
domestic pigeons for the hen to lay only one, especially towards the 
beginning or end of the season; and there are occasionally females 
which seldom or never lay more than one egg at a sitting. On the 
other hand, according to various authors (see, for example, quotation 
from Aristotle, p 478) they may occasionally lay three or even four 
(Wright, 1879, p. 33). Tegetmeier (1868, p. 10) asserts, however, 
that they never lay more than two eggs in a nest “unless, from the 
absence of a sufficient number of male birds, two hens pair and make 
a nest, when four are laid, which of course are sterile, and after being 
sat upon for the usual period are deserted.” We have had cases of 
three eggs, but none in which we could be absolutely certain that the 
third egg was laid by the same bird, though the cicumstantial evidence 
to that effect was strong. In at least one case the third egg hatched 
normally. 
Certain birds, at least, that normally lay clutches consisting of 
a considerable number of eggs, may be induced to continue laying 
for a longer or shorter time if the eggs are removed as laid. This 
is the case with most of our domestic poultry, such as the ordinary 
hen, duck, goose, turkey, and so on. The classical example of a non- 
clomesticated bird which has often been made to produce an unusual 
number of eggs in this way is the Flicker (Colaptes auratus). The 
usual clutch of the Flicker is from 6 to 9 eggs, but much larger 
numbers may be obtained if the eggs, or all but a “nest egg,” are 
removed as laid, the largest record being of 71 eggs laid in 73 days, 
beginning about May 6th. Burns (1900, p. 45) has given a summary 
of such cases for the Flicker, and also for a number of other wild 
birds. With pigeons, however, removal of the first egg is ineffective 
in inducing the female to lay any more than two at a time; nor 
have we yet found any method by which this result may lie brought 
