INTRODITCTORY. 



IX 



conditions unsuitable for the presence of one or other 

 race of birds. 



The vast increase of population, and the scientific 

 farming which drains every marsh and substitutes for 

 every bosky nook a rigid bank and paling mathemati- 

 cally drawn, are the chief causes of the decrease — both 

 in species and individuals — which has taken place in the 

 manufacturing districts ; but it is astonishing how many 

 birds still flourish among the teeming millions which 

 dwell there, and should it be possible for air and water 

 to become more pure, there is no doubt that, except in 

 the immediate vicinity of buildings, little further 

 diminution would occur. 



The way in which birds are driven away by the 

 extension of buildings, and by the conversion of a rural 

 into an urban locality, may well be instanced by the 

 case of Peel Park, Salford, which is one in point. Mr. 

 John Plant has kindly permitted me to use his notes, 

 which have been carefully kept since 1850, and which 

 show the following results : — 



Mr. Plant considers that the main causes are, not so 

 much simply the presence of more people and greater 

 disturbance by them, as the destruction of natural food, 

 and loss of protective foliage from the vitiated atmo- 

 sphere ; and he makes the melancholy prophecy, that, if 



