214 ROLAND F. HUSSEY 



as if for food; and I noticed that in this connection such sounds 

 as rustling paper or birch-bark were stronger stimuli than were 

 sharper sounds such as tapping or chirping. When the parent 

 returned it stood in the nest over the young, and was continually 

 on the alert. The usual sound stimuli were tried — tapping, 

 whistling, clapping the hands, etc. — and the usual reactions 

 were secured. Interrupting a sound by another of a different 

 sort produced vigorous reactions twice in three trials. For the 

 first time since July 10 the bird seemed to be made uneasy by 

 the sound of my pencil; when I started writing it gave a slight 

 reaction, and again when I stopped writing. This was the 

 first day since July 10, however, when the wind was blowing 

 from the tent toward the nest. 



When I made my first photographic exposure this morning, 

 the parent on the nest had ceased momentarily to watch the 

 tent and was bending over the young. The sound of the camera 

 aroused it to watchfulness again. Subsequent releases of the 

 camera shutter did not seem to attract the bird's attention 

 at all. 



July 20, 9:10-10:50 a. m. While the parent was absent I 

 tried the effect of a loud whistle blast on the nestlings. At 

 the first trial one of them raised its head, but five subsequent 

 trials produced no effect. 



When a parent returned I made some experiments to determine 

 to what extent reactions were inhibited when the bird was at 

 the nest. While it was approaching the nest and when within 

 a few inches of it, I tried various sounds, but without effect. 

 When this bird had finished feeding the nestlings, I gave a 

 loud whistle blast, and the bird started visibly. Later, when 

 a parent approached the nest again, and was still five or six 

 feet away, I tapped my note-book cover with my pencil, with 

 the result that the bird turned and ran off some fifty feet. When 

 it returned a minute later I repeated this experiment, and the 

 bird flew away and was gone several minutes. After several 

 feedings I made some further experiments, with the following 

 results: when the parent was coming to the nest and was 

 within a few inches of it, or when at the nest-side and engaged 

 in feeding the nestlings, it seemed to pay little or no attention 

 to sounds from the tent; but after the young were fed and the 

 nest was cleaned, it seemed always to notice them. Yet it 



