The Bcliavior of Noddy and Sooty Terns. 241 



One interesting fact, which bears out the contention of Lloyd Morgan, 

 became increasingly apparent. The birds at first show no discrimination 

 with reference to the objects at which they peck. I cite one instance in 

 detail: One bird defecated upon a white surface. A second bird ran up, 

 struck at the fecal matter, and got a quantity of it in its mouth. Movements 

 characteristic of " disgust " took place. The bird finally shook the material 

 out. A little later the same bird came up to the fecal matter again, struck 

 it this time lightly, and again shook its head and wiped its beak. About 

 30 minutes later this bird approached it a third time. Bird shook its beak 

 violently before it came within half an inch of the object and turned away 

 without further noticing the fecal matter. Two days later, in a similar 

 situation, bird again was stimulated by fecal matter, but turned away before 

 striking it. Many others of the birds were stimulated by this material, but 

 while thev were often at the point of striking at it, they always inhibited 

 the movement so that the fecal matter was never taken into the mouth. 

 Thev had in all probability already made the discrimination. 



On the thirteenth day a rather interesting association was set up by one 

 of my birds. In the bottom of the box (14 inches in height) in which I was 

 now keeping the birds, an old pair of trousers had been thrown with one leg 

 extending over the edge of the box. One bird climbed up the trouser-leg 

 and jumped down to freedom. This bird began scrambling out of the 

 box as fast as I could replace it. None of the other birds imitated this one 

 or ever escaped from the box by this method. 



Sixteenth day: 



A rather interesting development of the pecking reaction was noticed 

 to-day. Small twigs of cedar, matches, etc., were pecked at by the birds 

 and retained in their beaks. They made no efforts to swallow the sticks, 

 but would walk around the room with them with head extended, a complete 

 replica of the adult noddy throughout its nesting season (see p. 200). The 

 birds were tested on cooked " Cream of Wheat." They struck at it eagerly 

 at first, but soon learned to reject it in a manner quite comparable to the 

 learning of the rejection of fecal matter. 



Nineteenth day: 



There is a very noticeable increase in the ability to use their wings. 

 They are beginning to flop the wings and to use them in obtaining equilib- 

 riurn. They use them quite noticeably now when jumping down from a 

 height. The characteristic movements of wing and leg of the adult when 

 dozing on a limb in the sun were noticed for the first time. The wing 

 turned to the sun is drooped so as to shield the body, while the opposite leg 

 is stretched out, the body being supported by one leg. 



Beginning on the i6th day^ and during the rest of my stay on the island 

 the birds were fed only in the maze. At this age it becomes possible to use 

 food as a stimulus in controlling their reactions. The statement of the be- 

 havior of these birds in learning the maze will be given later on. 



The young birds in the field are slightly more developed at 19 days of age 

 than the birds held in captivity. I captured 3 of these birds at about this age, 



' The nodding reaction (p. 196) was noticed first in a perfect form on the 27th 

 day. Two birds were fighting; after a vicious thrust No. i backed away from No. 2 

 and nodded vigorously. Fighting adults often do the same. 



17 



