BRITISH WARBLERS 



degree of perfection in which we now perceive them, we shall 

 find that the task is neither so simple nor so easy as it may at 

 first appear to be. In a problem, too, of this description, it 

 is well to remember that simple principles of explanation are 

 to be preferred to complex, and in this instance a simple one 

 is at hand, namely, that the imitations have been acquired 

 by each individual during its own lifetime. How far is this 

 explanation satisfactory ? It is unquestionably true of a 

 number of cases. The Blackcap replies to the "jug" in the 

 Nightingale's song, repeats the song of the Eedstart, or 

 answers the "chuckle" of a Blackbird. In fact, numerous 

 instances could be given of a member of one species producing 

 an immediate representation of the song of one of another; 

 but this is really unnecessary, since it is well known that birds 

 kept in confinement have an innate proclivity for copying the 

 sounds they hear. But this does not exhaust all the possible 

 methods, neither do I think it explains all the phenomena 

 with which we are brought face to face upon closer examina- 

 tion. There are some grounds for believing that part of the 

 imitations may be congenital, the acquired imitation of the 

 parent being transmitted to the offspring. Needless to say, 

 the evidence I have hitherto been enabled to obtain bearing 

 upon this point is far from being complete ; a human lifetime 

 is too short for the accumulation of the necessary facts ; con- 

 certed observation on the part of a number of naturalists can 

 only justify a conclusion, but I place it upon record, hoping 

 that it may be the means of inducing others to investigate 

 what I think may prove a source of knowledge so far as this 

 much-debated controversy is concerned. 



I have already mentioned that the colouring of the imma- 

 ture males on their arrival in this country in the spring is not 

 so intense as that of the older birds, and that some of them 

 still carry the brown- tipped feathers on their head; conse- 

 quently, it is by no means a difficult matter to distinguish 

 them. They are just as vigorous singers, although their song 

 is not so perfect, and their power of imitation is considerable, 



32 



