PREFACE 



THE animal life or fauna of a country is no fixed unit 

 of occupation, established and unchanging, but, endowed 

 with the plasticity of life, it carries in itself the imprints of 

 many influences which have played upon it throughout the 

 ages. The lectures contained in the following pages were 

 planned to unravel one important set of such influences those 

 which radiate from the acts of Man so that it might be 

 possible to trace the different ways in which Man's power 

 has worked and is working, and to realize to what degree 

 a fauna of to-day owes its character and composition to his 

 interference. 



With this end in view it was necessary to select a particular 

 fauna of manageable compass, where the inquisition into 

 Man's influence could be pushed to the furthest limits ; and 

 several facts pointed to the fauna of Scotland as best suited 

 for the purpose. Nevertheless, I have not hesitated to refer 

 to examples of Man's influence in other countries, wherever 

 particular types have been strikingly illustrated, or where 

 influences are seen at work which help to explain effects of 

 causes long lost to sight in Scotland, or where, as in the case 

 of counter-pests, modern science has created new kinds of 

 interference which sooner or later are likely to be adopted 

 in this country. 



A result of this enquiry has been to emphasize the in- 

 stability and changefulness of a fauna, and a word may be 

 said as to the general place of Man's influence in the sum 

 of change. Two types of changefulness affect a country's 

 animals one temporary in. incidence and local in effect, a 



