28 HISTORY OF THE EUROPEAN FAUNA. 



an extent as to become a burden and pest to the 

 country. It may be remembered though, that, owing 

 to the complete absence of small carnivores, which 

 act with us as a check upon the too rapid increase of 

 this rodent, the speed with which it established itself 

 in the new surroundings is not so very surprising. 



Many of the English settlers in the New World felt 

 that America lacked the presence of our familiar 

 birds. The homely sparrow was therefore brought 

 over, with the result that the Agricultural Department 

 of the United States is now devising means for its 

 destruction, so rapid has been its increase. 



Similarly, the inhabitants of Jamaica, annoyed by 

 the great profusion of rats in their island, sent over to 

 India for a number of mongoose. These have deci- 

 mated the rats since their arrival, but they have 

 multiplied to such an extent as to be a serious 

 menace to the native fauna. 



To give an instance nearer home, the Capercaillie 

 (Tetrao urogallus) was successfully introduced into 

 Scotland in 1837. From its different centres of 

 distribution it is spreading in all directions where 

 sufficient cover is obtainable. But this case differs 

 from the others very materially, in so far as this bird 

 was formerly a native of Scotland, and only became 

 extinct during the last century. 



However, although there are many examples of un- 

 doubtedly successful introductions by human agency, 

 quite as many, or perhaps more, unsuccessful ones 

 might be quoted. In fact, it is by no means easy to 



