The Behavior of Noddy and Sooty Terns. 253 



being cast over many of the pathways; consequently the results are more 

 or less vitiated by this circumstance. I determined, however, to test the 

 birds under these conditions. The birds were kept in the room for 45 

 minutes before being tested in the maze. They were quite lively and hungry. 

 All other conditions of the test were the same as in daylight. The be- 

 havior of the sooties is shown in the following: 



Sootv I : Started the short way as usual, but the deep shadows seemed 

 to deter'him. Turned into E and came to O by the longer route. Time: 

 1.50 minutes. 



Sooty II: Bird ran quickly completely around II. Came out and ran 

 rapidly to L. Was deterred as in above case, ran into I and on into Z, came 

 back to L and ran the full length of L and J\I and then went out the short 

 way through S to O. Time: 2.66 minutes. 



'Sooty III : Ran out rapidly from H into I and then into Z, then turned 

 and went into R and then into E and ran up and down the alley R and E 

 three times. On the last trip passed on through F and G to O. Time : 2.80 

 minutes. 



Sooty IV (female) : This bird behaved very peculiarly. She spent 15 

 minutes in H. Came rapidly out to L, turned in there and ran the full 

 length of M, came back and ran up I into Z, then back down I and poked 

 head into R. Shadows there apparently disturbed her and she turned back 

 into L. Dug a little hole there in the sand and after standing furtive and 

 alert for 10 minutes, went to sleep. Total time under observation : 45 min- 

 utes. No success. 



It is perfectly clear from the above test that the birds can run the maze 

 in a faint light. Whether they can run it without error in the given illumi- 

 nation can not be decided until we can eliminate the shadows which were 

 mentioned above. 



On account of the unsatisfactory nature of this test the noddies were 

 not tried in the same way. 



The next night I tried the birds with the maze in total darkness. The 

 birds were carried in as usual and left in the maze room for half an 

 hour before being tested. An electric contact and signal had been arranged 

 to warn me when the bird stepped upon the inclined plane at 0. Great 

 care was taken to remove all tracings from the sand so as to get a complete 

 record of the trial movements of the birds. 



The results of this test are curious. Each bird was left in the maze at 

 its respective trial for 30 minutes. No signal reaching me, I then went in 

 with my lantern. Not a single bird had moved from its tracks. Each 

 had stood motionless at the point in // at which 1 had set him down. As 

 soon as light was brought into the room the bird began " peeping " and 

 moving. 



It is clear from these tests that the light conditions acli^'ity in these 



