502 
Bulletin No. 1G2.—1915. 
Length of Time Pigeons will Incubate when Eggs do not 
Hatch* 
It has been claimed by Raspial (1897, 1907) that Turtle doves and 
pigeons have a very nice adjustment to the normal period of in¬ 
cubation of the eggs, and that if these do not hatch at the proper 
time the parents will abandon them at once. In his earlier paper 
he reports the case of a female Turtle dove [“Tourterelle vulgaire 
(Turtur auritus ) ”] which twice had infertile eggs and abandoned them 
on the eighteenth day. He argues that since “about 18 days, ” is the 
period of incubation of the domestic pigeon, it is probably the same 
in all of the Columbidae, and this case accordingly proves that the 
dove “had a very exact notion of the period of incubation and 
the futility of sitting longer”! As a matter of fact the period of 
incubation of the Ring dove (Turtur risorius) is only about 15 days, 
and it is probably shorter in all the smaller doves than in the pigeon. 
In the second paper he refers again to the Turtle dove and adds the 
case of a homing pigeon which four times abandoned its eggs on the 
eighteenth day, the eggs in each case being infertile. He says it 
is then the knowledge by the female pigeon [Why the female alone, 
since both sexes take part in incubation?] of the time that should 
elapse for the eggs to hatch, that enables her to abandon them when 
they are infertile. Considering the extreme delicacy of the sense 
which Raspial claims to have shown “enables the Turtle dove to 
perceive when a profane hand has, during her absence, touched her 
eggs or young, and which leads to her abandoning them without 
pit}',” it is to him “astonishing that she has not the faculty of 
recognizing sooner that the life is not developed in so intimate a 
product of her generative organs, and that it is necessary for the 
whole period of incubation to elapse for her to comprehend the 
inutility of her efforts.” He is furthermore surprised to find this 
phenomenon in birds of the same family, but living under such 
different conditions, the one in captivity, the other free. He points 
out that in contrast to pigeons the domestic fowl has lost this “notion 
