November, 1922. The Irish Naturalist. 1 17 



BIRDS' SONG. 



BY J. P. BURKITT. 



This paper is a further study in continuation of two 

 previous articles.^ These studies of the seasonal course 

 of the song of some species and of many individuals, may 

 or may not produce anything of value or even of interest ; 

 but as hardly anyone is likely to take the pains, even if 

 he had the opportunity, to make almost daily notes 

 throughout the whole season, involving subsequently a 

 laborious abstracting of the notes, I feel the results had 

 better be recorded. Others may be able to make use of 

 them or to make comparisons. Individual members of a 

 species vary no doubt in song characteristics, but that taken 

 on the whole they follow a wonderfully similar course 

 seems more clear the more they are studied. Any generalisa- 

 tion about a species herein may be taken to represent as 

 faithfully as I can the great majority of its members. For 

 example I try to avoid such traps as that of a few strong 

 singers giving the erroneous impression that the song is 

 general. 



The theories put into my mind from the result of 

 observation run as folio w^s through the season. I have 

 mentioned them less coherently before. However far 

 they may be true, at any rate they afford a point of view 

 to connect the seasonal observations on various species. 



1. Mating generally puts a brake or stopper on song. 



2. Hence a declension of song for first nests and broods. 



3. But song is carried on more or less by un-mated 



birds. 



4. After the first brood there is a recrudescence of song. 



5. The later song lasts in the season the later the 



breeding lasts. 



6. There may be {a) no breeding, or (h) not much, 



after the second song, especially in Ireland where 

 such song ends sooner. In case [a) I called it 

 residual song (supra, p. 121). 



^ Irish Nat, vol. xxx, 1921, pp. i-io and 113— 124. 



A 



