6o Journal of Comparative Neurology and Psychology. 



The next utterance to be differentiated is the kah, and its origin 

 resembles that of the alarm-note in that at first it is given in the 

 sibilant baby voice yet with the rhythm and inflection of the adult 

 cry, under the same circumstances as the adult cry, and apparently 

 with the same meaning. Two young birds, of different broods, began 

 to give this call on the twenty-seventh day. Another brood of two 

 birds began, apparently, at exactly the same age, for I find in my 

 notes that on the twenty-seventh day they "have an intermittent call. 

 I|- is in the same tone as the ordinary squeak of the young and hence 

 resembles the contented chirnip of a chicken. It seems to be given 

 when the birds are moving about and sociaVe." This call is given 

 in nearly all the many circumstances in which the adult kah is given, 

 but it is not so commonly uttered upon merely alighting on a percli. 

 It is heard in general, as quoted above, "when the birds are moving 

 about and sociable," and it is heard particularly when the bird charges 

 upon another one, in which case the kah is often followed by the 

 bowing-coo. Like all other utterances given in the baby voice, this 

 kah may be imitated by whistling the letter S loudly through the 

 teeth ; the following notations will funiish a guide in such imitation. 



N0.29 



12* 



S 



#^ 



N0.30. 



^111111 



Time : 5 crotchets per second. 



The change of voice. — By the term "change of voice" is meant the 

 change from the high-pitched sibilant voice of the young to the more 

 grave and sonorous tones of the adult. It seems well to introduce this 

 topic here because, while the change of voice affects not only the 

 alarm and the kah but also the coo, which will not be treated until 

 later, yet in the coo it is complicated by the simultaneous occurnmce 

 of great changes in modulation, Avheroas in the alarm and tlic kah 

 the change in pitch is the only change which occurs. 



The change in pitch does not occur by a gradual deepening of the 

 baby voice; the voice "breaks," just as it does in a thirteen or four- 



