250 Papers from the Marine Biological Laboratory at Tortugas. 



than is the case with the birds observed by Porter. The reason for this 

 is quite clear when one recalls that the sooties will stand perfectly still 

 sometimes for an hour or more. Most of the time consumed by the birds 

 was spent in idling at H or in standing in some other part of the maze. 

 I have compared my record of " errors " with that given by Porter, and 

 find that if anvthine: the number of errors made bv the terns is less than 



I 2 3 A 5 6 V 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 35.26 27 28 29 30 31 32 33 34 



Trials 



Fig. 3. — Curve showing average time of four sooties in leaving Porter's simple maze. 



that made by many of Porter's birds. Porter records 3.5 errors for the 

 vesper sparrow ; 91 errors for the cowbird ; 7.5 for English sparrow F 5 ; 

 58 to 45 errors for English sparrow M 6; 121 errors for English sparrow 

 F 7 ; and 1 1 errors for English sparrow M 8, as being the total number 

 of errors made by his birds in their first two trials.^ It would be abso- 

 lutely impossible for the young terns, with their idling habits, to make, 

 within the time-limit shown above, anything like the number of errors which 

 some of Porter's birds made in the time shown in their records. 



If the time for idling, which is a characteristic mode of behavior and is 

 not due to a lack of hunger, were taken out the curve as shown above would 

 be much smoother and would lie very much nearer to the base line. If 

 the latter part of this curve be compared with the corresponding portion 

 of a similar curve obtained from the rat in learning the Hampton Court 

 maze,- its extreme irregularity as compared with the rats' curve will at once 

 become noticeable. The terns never become the automata which the rats 



* What do " errors " mean in such cases as these ! 

 " Watson, J. B. Op. cit., p. 100, curve iii. 



