The Behavior of NoJdy and Sooty Terns. 245 



Sixth day: 



There is slight improvenieiit in getting to the top of the box. The birds 

 are still very clumsy, but are becoming more and more eager. 



Seventh day: 



Birds eager for breakfast. Two walked up the platform before the fish 

 were shown"! Two others came up as the first two were being fed. Live 

 fish were given them to-day. The birds' movements are wonderfully fast. 

 The e.xtremely rapid movements of the fish are not faster than the action 

 of their beaks.' There is little improvement in discrimination tu be noticed. 

 To-day, while I was feeding some of the birds, I felt a tug from behind, 

 and on turning around, I found that one of them had swallowed about 3 

 inches of my handkerchief and was straining every muscle to force the rest 

 of it down ! 



At the second feeding on this day one bird ran immediately up the plan^ 

 and three others followed. When fish were presented these four birds be- 

 gan fighting vigorously. By the time they were fed. all of the other birds 

 had clambered to the top. 



The young birds were offered lemon peel to-day. It was snapped up 

 bv all the young birds eagerly. They continued to snap and swallow the 

 lemon rind' for three to four trials, and refused thereafter to open the 

 beak for it. 



Fighting is furious and prolonged. The }Oung birds are exact replicas 

 of the old in this respect. All that is necessary to start a fight is for one 

 bird to come within striking distance of another. 



Eighth day: 



The association of walking up the plane to feed was perfect in all of 

 the birds by the end of the last feeding on this day. They, however, had 

 not vet learned sufficiently well to feed without assistance from me. 



The voung birds began to-day to dig holes in the sand, using exactly the 

 same movements which are employed by the adults in digging the nest, 

 except that the young birds do not shape the hole with the breast as the 

 adults do the nest. By digging such a hole, the bird secures a surface which 

 is damp and cool. The holes are usually dug near some solid object, whether 

 because of greater coolness there, or through some thygmotactic tendency, 

 I am not able to state. 



A new instinctive reaction was observed to-day which is continued from 

 this time on. A bird standing still will suddenly hop an inch or two in the 

 air and come down in the same spot. As it descends it flaps its wings. 

 The value of this reaction in strengthening the wing muscles is apparent. 



'An old sooty with a broken wing, which had learned to come to the experimental 

 cage when the young birds were being fed, was carefully watched to-day. Live fish 

 were put down before it in a shallow dish. The bird would catch the fish near the 

 middle of the body and by a quick flirt would bring the fish around head end first 

 before swallowing'it. This bird's movements were extremely quick. If I offered it 

 a fish after it had been sufficiently fed, it would strike at the fish, take it in the beak, 

 and then let it fall. Young birds were seen to do this early. The old bird would 

 eat any variety of small fish but reiected sticks, grass, etc., after taking them into the 

 beak. Lemon rind was offered. The bird took it into the beak but quickly rejected 

 it. Would not take it a second time. 



