LESSER WHITETHROAT 
Thus far we have a clear case, since we are more or less 
guided by actual experience, but the subject now enters a 
more difficult and at the same time more speculative stage. 
I have referred to the great divergence in the song of the 
Lesser Whitethroat in Hungary, when compared with that 
in our Midland counties, and what we have to consider more 
particularly is how this change has been brought about. 
For this purpose it will be sufficient to confine ourselves to 
this one species, although it must by no means be thought 
that this is an exceptional case; other instances could be 
given showing quite as remarkable a variation. Now the 
influence of climate is no doubt considerable, but it is 
incredible that it can be so potent as to cause an immediate 
transformation each recurring season in the song of each 
individual migrant upon arrival at its destination; for this 
would not only imply an alteration upon its finally reaching 
its goal, but a continuous process of change from the moment 
it left its winter home. 
The Lesser Whitethroat, like the majority of our summer 
migrants, winters in Africa, and in the spring migrates north- 
wards to its breeding territory, in some cases passing over a 
ereat portion of Europe on its way thither; consequently we 
should have to assume that in every country, in almost every 
district, through which in its wanderings it would be com- 
pelled to pass, it would be gifted with a different voice and 
a different song, which is beyond belief. And if it be asked 
whether it is not possible that the change is produced 
gradually throughout the season, we can, fortunately, be 
guided in our reply by actual experience ; for it is an observ- 
able fact that no appreciable change does take place during 
the season; the song of the Lesser Whitethroat is the same 
both as regards type and tone upon the first day of its arrival 
as it is one or two months later, excepting as regards the 
eradual deterioration in quality, which is common to all 
species whose vocal powers are highly developed, and is a 
different matter. If, therefore, we are right in concluding 
19 
