308 Capt. H. Lynes on the Geographical Distribution 



the colour-differences being obvious at first glance, all three 

 birds have the bill quite remarkably robust, larger in every 

 dimension than in any of some thirty P. c, collybita examined 

 alongside them. 



Here^ then, we have the Canarian bird differing in certain 

 habits and in form from its typical species, while in a 

 certain district (restricted, but to what extent we know not 

 yet) intermediate between their breeding-areas, are breeding 

 ChifFchafFs with habits resembling the former, but with the 

 typical form. 



An interesting line of thought is thus provided. 



There are many good reasons for thinking that the '^habit" 

 of song ^ may be correlated with others, such as ''migratory 

 movement^' — in fact, these south European, and particularly 

 the Gibraltar, Chiffchaffs are generally quoted as being 

 '^ resident " or " sedentary^' (although, as I propose to point 

 out later, I believe this to be mere guesswork). It is, 

 moreover, an observed fact in Nature which provides 

 interesting reflections on the inter-relationship of variation 

 in " habit " and variation in " form." 



Darwin (Orig. of Sp. p. 220) says ''It is, however, difficult 



to decide whether habits change first and structure 



afterwards, or whether slight modifications of structure lead 

 to changed habits — both probably occurring simultaneously .'■' 



Anticipating, for instance, what requires the accumulation 

 of a vast amount more fact before the truth can be arrived 

 at, it is conceivable that here is an instance of what may be 



* Professor Newton (Diet. Birds, p. 893) says : " A curious question 

 wliicli has yet attracted but little attention is whether the notes 

 of the same species of bird are in all countries alike. From my 

 own observations I am inclined to think not, and that there exist 

 ' dialects,' so to speak, of song {cf. Gloger, J. fiir Orn. 1859, p. 398 ; 

 Allen, Bull. Mus. Comp. Zool. Harv. Coll. ii. pp. 166, 167)." 



Eliot Howard (Brit. Warblers, p. 20) points out certain differences 

 in song among Warblers and Chats in different localities and suggests 

 that '' there is a possibility, even a probability, perhaps, of some con- 

 nection between type of song and climate." 



Witherby (' Ibis,' 1905, p. 186) notes the remarkable difference 

 between the song of the Wood-Warbler in Algeria iu April and that of 

 our British Wood-Warblers. 



