BIRDS SPECIAL HABITS OF INCUBATION 287 



one of the number perceives a carcass and begins to de- 

 scend, the next adjacent vultures would see the descent of 

 the first one, and follow him as a guide, while the next in 

 the series would follow these in the same way, and so on. 

 Coining now to special instincts relating to incubation 

 and the care of offspring, a correspondent writes : 



Last spring I had a pair of canaries, in an ordinary breed- 

 ing cage (with two small boxes for nests in a compartment at 

 one end). In due course the first egg was laid, which I inspected 

 through the little door made for that purpose. The next day I 

 looked again ; still only one egg, and so for four or five days. It 

 being evident, from the appearance of the hen, that there were 

 more eggs coming, and as she seemed in good health, I supposed 

 she might have broken some ; and I took out the box, and exa- 

 mined it carefully for the shells (but without pulling the nest 

 to pieces), and found nothing, until towards the beginning of 

 another week I went to take the one egg away, as the hen 

 seemed preparing to sit upon it. There were two eggs ! The 

 next morning, to my surprise, she was sitting upon six eggs ! 

 She must therefore have buried four of them in the four corners 

 of the box, and so deep that I had been unable to find them. 

 At first I thought that she had done so merely from dislike at 

 their being looked at, but on reflection it has occurred to me 

 that she did it that all might be hatched at the same time (as 

 they subsequently were) ; for she was perfectly tame, and would 

 almost suffer herself to be handled when on her nest. Wild 

 birds never seem to conceal their eggs before sitting; but then 

 (having more amusements than cage birds) they do not revisit 

 their eggs after laying, until they have laid their number, 

 whereas a caged bird, having nothing to divert her attention 

 from her nest, often sits on it the greater part of the day; 



I am not aware that this curious display of forethought 

 on the part of a caged bird has been hitherto recorded, 

 and seeing, as my correspondent points out, that it has 

 reference to the changed conditions of life brought about 

 by domestication, it may be said to constitute the first 

 step in the development of a new instinct, which, if the 

 conditions were of sufficiently long continuance, might 

 lead to an important and permanent change of the ances- 

 tral instinct. 



I have several interesting facts, also communicated to 



