INTRODUCTION 17 



element, either for good or for evil, profiting 

 readily by the former, and being adversely affected 

 by the latter, even to the extent of more or less 

 rapid extinction. Numerous instances might be 

 given to illustrate how readily certain species have 

 profited by the decrease, say, of their natural 

 enemies, or the initiation of easier conditions of 

 existence ; and, on the other hand, how disastrous 

 have been the effects of similarly changed conditions 

 acting in a directly opposite manner. We have, 

 for instance, much cause to regret the rapid 

 increase of the House Sparrow, partly due to the 

 wholesale slaughter of birds of prey, and partly 

 to the exceptional facilities for shelter, abnormal 

 reproduction, and the constant and abundant 

 supply of food, due to the march of modern 

 civilisation and the spread of agriculture. We 

 have equally to regret the disappearance from our 

 avifauna of such species as the Great Bustard and 

 the Crane. Bird lovers may well deplore the final 

 disappearance of such magnificent species from our 

 islands, due indirectly, to some extent, to the changed 

 conditions of the century now drawing to a close, 

 but more to the growth of sport, the increase of 

 gunners, armed with more deadly weapons, and 

 the rapid multiplication of the avaricious class of 



