INSTINCTS AND HABITS IN CHICKS 7 



together without marked activity in other regions of the organ- 

 ism, so the chick during the first few hours after exclusion may- 

 be seen to work its mandibles in a similar way without disturb- 

 ing its sitting posture. The pulses of activity, embryonic and 

 post-embryonic alike, are often accompanied by loud chirping. 



One might expect to find more unmistakable evidence of a 

 pecking reaction while the chick is yet within the egg. There 

 is an impression abroad that the chick pecks its way out of the 

 shell. When the position of the head in the embryo is taken 

 into consideration, one can see two reasons why most of the 

 movements of the head are lifting movements, and not pecking 

 reactions: (i) the lifting mqvement tends to free the head and 

 neck from their folded position, and (2) pecking would seem 

 to be a difficult matter with the head folded down on the breast 

 in this wise. Besides, the lifting reaction does actually break 

 shell and tear confining membranes, and so is effective in releas- 

 ing the chick. It may be found that the chick does not peck 

 its way out of the shell. However, the matter will need more 

 careful study. For hours I have watched chicks laboring in 

 the egg to discover a clear case of the pecking reaction. At 

 times, before the egg has been broken in two, one does see short, 

 quick, forward thrusts of the bill followed by working of the 

 mandibles. And chicks only a few hours out of the egg may 

 be observed repeatedly executing what might be called a pecking 

 reaction " into the air," followed by clapping together of the 

 mandibles. The following note describes the reaction more 

 adequately: " Chicks after exclusion, on becoming aroused from 

 a dormant period, often open bill with a chewing motion and 

 sometimes thrust the bill forward sharply into the air even 

 without fully opening the eyes, no object, apparently, being 

 pecked at. Noticed a number of times." 



The following activities, generally recognized as instinctive, 

 were observed within the incubator on the first day, before 

 the chicks were completely dry: Preening the down of the 

 neck, wings, and breast; flapping of wings; chirping; walking; 

 pecking; lying on side and stretching out legs (in the rays of a 

 16 c.p. electric lamp); following a moving object with a motion 

 of the head; and chirring. Scratching, twittering, and wiping 

 of the bill have been noticed on the second day when the chicks 

 were taken out of the incubator for the first time and placed on 



