VA RIA TION IN BIRD- VOICES 1 57 



whitethroat, greenfinch, all become prolonged as the 

 season of song advances ; though this feature, of 

 course, is not restricted to the breeding season in all 

 these species, for the adult robin and starling, at least, 

 recommence their notes early in August, while the 

 skylark, wren, and hedge-sparrow sing sometimes in 

 autumn. 



In treating of imitation, I shall have something 

 to say about local variations and what caused them ; 

 I will, therefore, not now say more than that the 

 local variation mentioned by Bechstein and by Mr. 

 Ward Fowler, as occurring in the yellow-hammer 

 and the chaffinch, may be clearly traced in some 

 other species. 



It should be remembered that there are variations 

 in the rate of uttering notes, as well as in their 

 actual pitch, a feature especially noticeable in the 

 robin's lit it it alarm. There is often an extra- 

 ordinary extent of diversity in the utterance of 

 this alarm, and of the accent accorded to the notes. 

 I once attempted to record this exclamation, as sung 

 by a robin, and wrote large dots for loud notes, and 

 small dots for soft ones, and left spaces to indicate 

 the amount of time elapsed between them. Each 

 line represents one utterance of the alarm, and 

 should be read from left to right. 



