2^6 Papers from the Marine Biological Laboratory at Tortugas. 



Ninth day: 



I began feeding the birds in Porter's^ simple maze. The description of 

 their behavior in learning this maze will be given further on in the paper. 



Detailed records of the development of these birds were kept until they 

 were 30 days of age, but on account of the great similarity of these later 

 records to the above, I shall not cite them in detail. Experiments on learning 

 to discriminate were made from day to day, but all such tests gave results 

 very similar to those which have already been described. After the birds had 

 learned to pick up the fish from a dish, it was possible to put seaweed, grass, 

 bits of coral, etc., in with the fish. At first these were taken eagerly, but 

 after a few trials the birds would learn to take the fish and leave the debris. 

 Discrimination, however, never became very accurate. When very hungry, 

 the bird would attack objects other than the fish. I think this is but natural, 

 since the young bird feeds entirely from the beak of its parent until it is 

 able to fly and fish for itself. They certainly get nothing there which would 

 tend to develop discrimination. 



It may be of interest in this connection to say a few words about the 

 way the young birds in the field and those in captivity spend the greater part 

 of their time. I have already remarked upon the fact that there are no signs 

 of play. This was as nearly true of the birds in the field as of those ob- 

 served in captivity. The only reaction which it is at all possible to consider 

 a playful one is the one already mentioned, namely, the frequent hopping up 

 and flapping of the wings. There is a question in my mind here as to 

 whether after all Gross's theory of play fits the facts in any other genus 

 of animals so well as in the case of mammals. Certainly the facts which 

 I could gather with reference to both the noddy and the sooty terns do not 

 lend support to his theory. These birds certainly lead an instinctively com- 

 plex life. Surely the picking up of a live fish darting over the surface of the 

 water is as complex an act as the catching of a mouse. 



The greater part of the time is spent in doing absolutely nothing. The 

 birds will lie outstretched in their sand-holes, getting up at times to stand 

 stockstill for an hour or more, or to doze with head bent down. At inter- 

 vals they peck at their feet and occasionally preen their feathers. In the field 

 the routine is broken by the call from the parents which have returned to 

 feed the young. At other times the young bird gets hungry ; at such times 

 it begins to cry lustily and to go up to the parent (which is likewise standing 

 or fighting in the neighborhood) and begs for food by " peeping " and by 

 striking at the parent's beak. Getting nothing, the bird will wander oft" for 

 10 to 15 feet into the shade and lie down again. Frequently it engages 

 in fights with other young birds. Occasionally it will attack an adult noddy 

 which has dropped down to gather sticks. The young sooty never attacks 

 an adult sooty. 



' Op. cit., p. 253. 



