The Behavior of Noddy and Sooty Terns. 239 



ing. With birds in captivity the visual stimulus alone is not sufficient to pro- 

 duce all the movements necessary to feeding. They do not raise their heads 

 and open their beaks wide as do the young sooties. The food has to be 

 placed on a level with the head, then at gentle tapping, the beak begins to 

 open. There grows up a very rapid tendency on the part of the bird to 

 work a fish into such a position that it can be swallowed head first. I 

 found that their aim in pecking was not very accurate. Even after they 

 are stimulated to begin striking at the fish with open beak they will strike 

 above or below it, nor do they open the beak commensurateh' with the size 

 of the fish. Apparently both sensory and motor sides of this visual-motor 

 reaction need strengthening. Whenever the bird is disturbed, or when it is 

 being fed, it continually emits the above plaintive little note. It is instantly 

 hushed if the hand is placed over it. It huddles under the hand, turning, 

 however, so as to keep the head and beak out (a characteristic reaction when 

 under the breast of the parent). Coordination in walking is apparently 

 little further advanced. 



Third day: 



The birds eat more freely, but their appetites are in marked contrast to 

 the sooties of the same age. The movements of the noddies in taking food 

 from me are still not perfectly coordinated. They are better able, however, 

 tiian a sooty correspondingly young to swallow a minnow taken crosswise 

 mto the mouth. The birds are still very quiet. In the early morning, while 

 the young sooties kept in captivity are raising a noisy chorus, not a sound 

 comes from the noddies. 



The birds were tried again in the water. This time the leg movements 

 were fairly perfect. The head and neck were kept well above water and 

 they managed to swim until the down became soaked. When the bird 

 began to sink and water was taken into the mouth, disgorgement took place. 

 A good deal of increase in strength was noticed in the movements of the 

 wings, neck, and legs. Birds were observed pecking both at the ground 

 and at one another, but as yet no fighting was noticed. 



Fourth day: 



The birds are eager for their food. Feeding from me, however, is still 

 not perfectly done. My finger is often pecked at in place of the fish. They 

 peck more frequently at one another, and I noticed for the first time one 

 pecking at the fish another was trying to swallow. When one bird is fed at 

 the edge of the box, the others immediately begin to crowd up near my 

 hand. Either there is a following instinct being exhibited here, or else an 

 association has been formed. 



The birds were taken to the sand and put down. They moved about 

 very slowly. I separated them about 15 inches. In 10 minutes all had 

 collected into one group and stood huddled together. Up to the present 

 time there is no association established between a call on my part and a 

 hastening toward me or an answering call on theirs. The sooties very soon 

 learned to answer my call by running toward me and giving vent to a 

 lusty " peep." 



Their sleeping attitudes were observed for the first time. They lie 

 with the ventral surface of the breast down ; head stretched out and turned 

 to one side, sometimes both legs stretched out, sometimes only one. They 

 were noticed to-day preening their feathers by movements characteristic of 

 the adult. This was a very complete act. 



