THE REACTIONS OF BIRDS TO SOUND STIMULI 215 



was by no means as responsive (on this date) to any sounds 

 from the tent as to the very faint lisping sounds with which 

 the young asked for food. 



July 21, 8:30-10:45 a. m., 1:20-2:30 p. m. One of the 

 nestlings was lying in the nest, when I entered the tent, with 

 its head raised and bill opened so that the lower mandible lay 

 on the edge of the nest. I clapped my hands several times at 

 considerable intervals, and each time the young bird responded 

 by raising its head nearly to a vertical position and closing the 

 bill slightly. When a parent returned I repeated the experiments 

 of the day before, and again I found that the reactions were 

 greatly inhibited when the bird was at or near the nest, and 

 that the bird when at the nest seemed to pay much more 

 attention to the sounds made by the young than to any sounds 

 I made. In the afternoon I repeated experiments on the nest- 

 lings, but the only response obtained was similar to the one 

 just described. 



July 24, 8:05-11 a. m. During the first fifteen minutes of 

 the period the young were very quiet. I observed that whenever 

 I made any sudden loud noise, one of the nestlings invariably 

 raised its head, opened its eyes, and (apparently) watched the 

 tent for a few seconds. If the sound were repeated, it did not 

 show any further alarm, but merely continued to watch the 

 tent for a somewhat longer period than if the sound were not 

 repeated. I also noticed that the nestlings never seemed to 

 be aware of the approach of the parent, whether it ran or flew 

 to the nest-side; and it was my experience that its flight was 

 very noisy, with loud whirring of the wings, when it approached 

 the nest. In direct contrast to this was the case of some cedar 

 waxwings which came to my attention during the summer; 

 here the nestlings seemed always to be aware of the parent's 

 approach at a distance, and for some time were in a state of 

 expectancy. 



Except in the cases mentioned in the preceding paragraphs 

 I was never able to obtain any marked response from the nest- 

 lings to sudden and loud sounds. This seems to me to be 

 directly contradictory to a statement of Lloyd Morgan (Animal 

 Behavior, p. 49) to the effect that young birds " show signs of 

 alarm at any sudden and unaccustomed sound." After I had 

 been in the tent twenty minutes and the young birds had become 



