NOTES 



BEHAVIOR OF THE YOUNG BIRD IN BREAKING OUT 



OF THE EGG 



WALLACE CRAIG 



The University of Maim 



The older naturalists, especially Reaumur, made some careful 

 observations on the behavior of chicks in breaking out of the 

 egg. Their observations are summarized in one 1 of Rennie's 

 excellent little books. The main facts are these. The chick 

 chips the egg a little at a time with its bill, and as it does so it 

 turns around inside the egg-shell, the axis of its rotation being 

 precisely the long axis of the egg. The consequence of this 

 turning is that the tip of the bill, chipping the shell as it goes, 

 describes a very exact circle around the large end of the egg, 

 and thus the large end of the shell is cut off. The time which 

 it takes to finish the cutting is very variable. When the opening 

 has been extended nearly or quite around the egg, the chick 

 pushes in such a way as to separate the two sections of the 

 shell and tear any shreds of membrane which may have been 

 holding them together. Thus the little bird effects its escape. 



From the fact that pigeons' eggs are invariably opened by a 

 cut which neatly encircles the large end, we should infer that 

 the young pigeon opens its egg in the same manner as does 

 the young chick. And this conclusion is confirmed by the 

 following observations on two young doves (Turtur risorius). 

 The accounts are transcribed from my notes. 



"No. 46, April 19, 1 91 1. 8:30 A. M. My wife found egg 

 chipped and called me to see it. While we watched it, the young 

 chipped the egg about one-third the way round (120 ) in about 

 ten 'minutes. '■-. The young made a strong movement, then rested 

 for several seconds, then made another strong movement, and 



1 [Rennie, James. Published anonymously.] The Domestic Habits of Birds. 

 London, Charles Knight, 1833. 



296 



