The Behavior of Noddy and Sooty Terns. 233 



west and fought the wire for 3 seconds, liesitated at the north, then dashed 

 round to the cast and into the opening. Time, 0.13 minute. 



Opening was then turned south (the bird usually alights at the south). 

 Result: First trial: Ran into opening before I could move away from the 

 nest : not the slightest useless movement. .Second trial : Ran into box be- 

 fore I could time him. I repeated the above tests on the female with 

 similar results. 



If the behavior of the birds under the conditions of the above test is 

 contrasted with the behavior of the rat under conditions of a similar test, 

 one is struck by the very great rapidity with which the birds make these 

 adjustments. Turning the box as was done above and presenting it to the 

 rat would have caused him the greatest difficulty. I conclude from this that 

 the bird makes these adjustments largely on the basis of visual data, whereas 

 in all probability the rat makes the same adjustment by means of kinesthetic 

 data.' 



Experiment IV. 



After these animals had been accustomed to having their nest cov- 

 ered with this box for some 2 or 3 weeks, it occurred to me that if the 

 recognition of the nest is accomplished largely by means of visual data, 

 they ought to react to the box, even though it were moved from place to 

 place without being disturbed very markedly by the change so long as it 

 was not carried outside of their range of vision from the point where they 

 alight. The box was first moved 88 cm. due north (entrance west as usual), 

 while the egg and nest were left in the old position. 



Result: The bird (male) sat on the egg immediately without so much 

 as looking at the box, which was in plain sight 88 cm. to the north. After 

 sitting on the egg for a moment, the bird became imeasy, left the egg and 

 went over to the box and entered it, and then returned to the egg. He 

 repeated this procedure three or four times. On the last two trips, after 

 entering the box and not finding the egg, went round and round the box. 

 \M:ile he was doing this the female, which was standing on guard nearby 

 (up to this time inactive, however,) rushed over to the egg and covered 

 it. The male came back and drove her away and remained in comfort 

 on the egg. 



I then went to the box, scooped out a nest in the ground inclosed by it, 

 and put in an egg from a nearby nest. Result : Returned and sat on his own 

 egg, but craned his neck and peered at the box, showing evident signs of 

 " interest " in the box. 



I next removed his own nest, leaving the box as in the above test. Re- 

 sult: Bird ran first to box, then back to old position of nest. He turned 

 round and round in this spot, attempting to find egg. He then dashed for 

 the box, entered and sat on egg, but was not quite comfortable and kept 

 peering out the door and into the corners of the box. He then got up, 

 walked around the cage once or twice, came back to the egg and adjusted 

 it, and sat down in apparent comfort. Time for this readjustment : 0.66 

 minute. 



^ Watson. John B. Kinesthetic and Organic Sensations, etc. Monograph Snppl. 

 Psy. Rev., No. 33, p. 85. 



