234 A'Ac'-*' from the Marine Biological Laboratory at Tortugas. 



If the behavior of this bird be contrasted with that of others whose nests 

 had been disturbed (p. 225), it will be found that his readjustment to the 

 nest in a new situation was very much more rapid than in the case of the 

 former. Apparently, a partial but incomplete visual association had been 

 established between the nest and the box. It is clear in this test that if rec- 

 ognition of the nest is not accomplished entirely by means of visual data, such 

 data can nevertheless play the fundamental role under certain conditions. 



E.XPERIMENT V. 



A heavy focusing cloth of rubber was placed over the box, leaving only 

 the entrance, which was west, uncovered. The egg could be seen dimly, but 

 the rest of the box was extremely dark. In order to see the egg the bird 

 would now have to approach the nest and go very close to the door. 



Result: Bird apparently frightened at the dark object as a whole. Hov- 

 ered over the box, but would not alight. Finally alighted and went up to 

 within one foot of the entrance and" peered in. His reactions were very 

 curious. Went over to east corner of cage, peered at the covering, then 

 backed off. Approached the entrance and peered in. Started in, but his 

 courage deserted him. He did not go round and round as formerly. This 

 probablv was because the visual stimulus of the egg was cut of. He finally 

 poked liis bill into the door, pulled his head back, then began a curious pro- 

 cedure of flying 10 feet away and flying back to the nest, rejieating this in 

 rapid succession. In conscious terms, this behavior suggested that the origi- 

 nal orientation was in some way recognized by the bird as being wrong, and 

 that bv leaving and again approaching the bird sought to secure better orien- 

 tation' This lends support to my statements above that if the stimulus to the 

 nest depends upon visual factors the latter must be complex. The bird then 

 came to the door, stood near it, poked head in and withdrew it, repeating 

 this 15 times without moving from his position. At the end of half an 

 hour he entered and stayed for a moment, but rushed out again. Entered 

 two or three times againi but would not remain. At the end of 45 minutes, 

 after many such timid entrances, the bird walked in and sat down in com- 

 fort. I scared him away. He returned immediately and brooded the egg. 

 He had become entirely adapted to the changed conditions. 



These experiments, inconclusive and unsatisfactory as they are, never- 

 theless show that a definite question has been raised concerning the modus 

 operandi of nest recognition and nest orientation, which is entirely open to 

 experimental treatment. They likewise show that the nest locality, what- 

 ever may be the stimulating factors present, may be used at will as a stimu- 

 lus in controlling the reactions of the birds. 



SOME PRELIMIN.'\RY EXPERIMENTS WITH NODDIES UPON THE 

 LEARNING OF PROBLEM BOXES. 



A few experiments similar to the above were tried on the noddies. A 

 cubical box, 45 cm. to the side, made of wire mesh (12 mm.), was inverted 

 over the nests of noddies built near the ground. A 9 by 12 cm. opening was 

 inserted in one side of the box on a level with the top of the nest. The 



