77/t' Behavior of Noddy and Sooty Terns. 243 



after this age this process is easier with them than is the case with the 

 noddies of a corresponding age. In the case of the sooties, as was not the 

 case with the noddies, the mere sight of the food will cause the bird to open 

 its beak. Light contact will likewise cause beak to open. Once the food 

 gets into the mouth the rhythmical movements of swallowing follow per- 

 fectly. 



Some locomotion is possible. They take a few wobbly steps with wings 

 down and legs wide apart. Fairly well coordinated swimming movements 

 are present, but the heavy down with which their bodies are covered soon 

 causes the birds to become water-logged and they consequently sink. As the 

 salt water begins to enter the mouth the bird raises its beak higher and 

 higher and shakes out the water vigorously, crying lustily the while. 



One of these young birds had not emerged from its shell ; only its beak 

 and the base of the beak protruded (eyes being covered by a membrane). 

 Almost any call from me would cause this bird to " peep." Small minnows 

 were offered and swallowed. The contact of the minnows caused the beak 

 to open. I removed the shell ; the bird made adaptive movements as if com- 

 pleting the process itself. After removal the bird was very insecure in its 

 movements. 



Second day: 



The difference in growth is remarkable. Locomotion must have im- 

 proved 100 per cent in the 12 hours. Birds can waddle around rapidly and 

 maintain upright position fairly well. They follow moving objects with the 

 head and eyes quite easily. Will dodge very quickly if hand is suddenly ex- 

 tended toward them : Some tendency present to nestle under one another, 

 under my hands, and under the folds of the cloth. Birds are beginning to 

 peck at one another, the raw wings being the spot usually attacked. 



Feeding is quite easy. Moving the finger, fish, or bits of straw rapidly 

 across the beak will cause the beak to open wide. Whole minnows are 

 swallowed with ease. The birds sleep a great deal of the time. The adult 

 birds flying over the experimental cage and calling are invariably answered 

 by a " peep " from the young birds. Even on the second day feeding is an 

 active process with them. A fish dangled in front of them will cause them 

 to strike at it. If the beak fastens upon the fish in the center of the body 

 the young bird by a peculiar shake and twist of the head will suddenly right 

 the fish and swallow it head first. It is safe to say that at the end of the 

 second day the young sooty is sufficiently developed to take any fish from 

 the beak of the parent which is likely to be found there. 



Even at this early age the birds are found pecking at one another's 

 mouths or at a piece of food which another is swallowing. Pecking at one 

 another in a way forceful enough to suggest the beginning of the enor- 

 mously important fighting instinct was, however, not noticed up to this time. 

 Any signs of fear which might have been present the first day have entirely 

 disappeared by the end of the second. 



Third day: 



The birds have begun to run toward me when I approach them and call. 

 They will lustily answer my " peep " at any hour of the day or night. 



The fighting instinct appeared to-day in almost completed form. Two 

 of my young birds faced each other and began striking simultaneously. A 

 hold is taken on the bodv and maintained with grim determination, the 



