NESTING ACTIVITIES OF NODDY AND SOOTY TERNS. 83 



were made (6 inches or so per day) the nests were either abandoned when 

 moved 4 feet or less from their original position, or the eggs were rolled back 

 as fast as they could be moved forward. 



Note. — This moving of the egg back to the original position of the nest has been men- 

 tioned before in connection with other experiments. It might seem to involve very com- 

 plex processes, memory of the relative position of the egg and nest and an attempt to restore 

 their relation. I watched the entire procedure in a dozen or more instances and beheve 

 that there is httle implicit behavior involved in it. The bird, returning to the empty nest, 

 misses the egg, looks about, and catches sight of it a few inches away. She starts towards it 

 rapidly, but goes more and more slowly as she approaches, sometimes turning back before 

 reaching it. Perhaps after several such hesitating starts she gets close to the egg, stops as 

 soon as she can reach it with her beak, and rolls it back under her body. In this way the 

 egg is moved for 2 or 3 inches at each trip from the old nest site to the egg. That it is 

 moved in the direction of the old nest site seems to be the result of the fact that the bird 

 always faces away from the latter as she approaches the egg. There is no real evidence of 

 implicit behavior in this case, even of a delayed reaction in which orientation is held as the 

 egg is moved. 



In all its activities, where reaction to a new situation is involved, the beha- 

 vior of the birds has a peculiarly impulsive character. One group of stimuli 

 seems to gain momentary control and determine the bird's reaction in spite of 

 contradictory elements in the situation as a whole. If a chick is taken from 

 its nest and put down among strange adults they are at once attracted by its 

 cries and crowd around it. Several of them attack it and immediately others 

 rush forward to defend it. The fight becomes general and may give the chick 

 a chance to escape. After a time some of the adults are driven away and 

 leave the victors to strut about. If one of these catches sight of the chick, he 

 attacks it and the fight is soon renewed. I have seen the same bird alternately 

 attack and defend a chick through a number of fights ; the sight of the strange 

 chick calls out movements of attack; the sight of an adult attacking a chick 

 calls for defense of the chick. Young chicks, when attacked by adults, either 

 feign death or sprawl about helplessly, without being able to escape. In the 

 latter case they sometimes force their way under the body of the adult. When 

 this happens it practically always produces a marked change in the behavior 

 of the adult bird. His aggressive attitude drops away suddenly, he shuffles 

 about for an instant, looks down at the chick, tucks it under him with his 

 beak, and assumes the brooding position. If he is at some distance from his 

 nest this brooding reaction is of short duration; he soon grows restless, gets 

 up and turns around several times, and finally returns and attacks the chick 

 with renewed savagery. 



The same lack of coordination in reactions to complex situations is seen in 

 the choice between two nests, in the re-orientation in the path to the nest, and 

 in the reaction to changes in the appearance of the path. The reactions are to 

 separate groups of stimuli and there is clearly no analysis of the situation as 

 a whole. The birds do what a man would only consider doing under like 

 circumstances; that is, they carry out in overt activity many of the same 

 processes which in man are restricted to the language mechanism. In sub- 

 jective terms, they show little or no evidence of "ideational processes" in 

 their activities. 



