98 EVOLUTION OF BIRD- SONG 



it repeats this note many times in succession, and thus 

 produces a rattle not unlike the rattling alarm of 

 the robin. The young robin, when about to be 

 fed by its parent, frequently repeats its call-squeak, 

 which is merely an immature utterance of the call- 

 squeak of the adult ; and when food is being given 

 to it by the parent, a curious repeated sound, like 

 the word cah whispered very loudly, is also heard. 

 When the young redstart is fed these two sounds 

 are heard, in tones so like to those of the robins, 

 that I have several times mistaken the identity of 

 the birds which uttered them. The telescope 

 enabled me to arrive at a correct conclusion on the 

 matter. In the adult redstart the sharp click of 

 alarm is generally preceded by the single utterance 

 of a short upwardly-slurred whistle, somewhat louder 

 than, but otherwise like, the alarm and call-note of 

 the young and adult chiffchaff and the full-grown 

 and adult willow -warbler. It may be whistled 

 thus: 



The wide range of this cry, which I have heard 

 uttered by redstarts at Stroud, Dean Forest, New 

 Forest, Oxford, and other places, and the fact that 

 it is an alarm- cry, are of value as linking the 



