420 THE ZOOLOGIST. 



are absent, as compared with a dry climate, are those where the 

 high notes are introduced. I do not mean that the song is not 

 as beautiful ; for I have listened to Wrens in Donegal singing 

 quietly, whose notes, certainly not many, for fulness and rich- 

 ness of tone, were equal to the finest notes of the Blackcap. 

 The same phenomenon applies to the song of the Whitethroat. 



Different species appear to be subject to this climatic 

 influence in different degrees of intensity. For instance, the 

 variation to be found in the song of the Buntings is very small ; 

 I found great difficulty in detecting any variation at all in the 

 song of the Yellow Bunting. The same thing applies to the 

 song of the Tits, the Coal Tit having the least variation. On the 

 other hand, the variation in the song of the Warblers — Wren 

 and Blackbird — is most marked, that in the Whitethroat and 

 Sedge-Warbler being very striking. 



These facts seem to point to the variation being propor- 

 tionate to the development that has taken place in the song 

 of a given species, and I think it can be readily understood that 

 the most highly developed, and, therefore, most sensitive, musical 

 instrument would most probably be subject to this climatic 

 influence in the greatest degree. 



There is another phase of bird song which might be confused 

 with this dialectical change, namely, the song of the immature 

 males. The males of probably all species do not get their full 

 song for some years, in the same way that they do not really get 

 their full plumage — I think it very probable that the two corre- 

 spond ; but this song of the immature males differs rather in 

 the direction of fulness and richness of tone than in any actual 

 change of the song, and is very easily distinguished from this 

 ' dialectical change. 



My observations in a damp climate have always been made 

 either in March or July. I think that a close study of the 

 migratory species on their arrival in this country would, by 

 settling certain difficulties, throw some light on the whole 

 question. Is this change to be found immediately on their 

 arrival, or does it increase as the season advances ? Is it per- 

 manent, or only temporary ? The difficulty, as I mentioned 

 previously, is that it is impossible to compare notes with anyone 

 making similar observations, and it is also obvious that it is 



