284 CAUSES OF MIGRATION AMONG QUADRUPEDS. 



waters. The great migrations of the buffalo to which 

 Mr. Pike alludes and which formed such wonderful 

 spectacles in former days, probably arose from both 

 these causes, while the still more marvellous migrations 

 of the springbok, in South Africa, were undoubtedly 

 due to the failure of the water supply and the drying 

 up and withering of the vegetation. In equatorial 

 regions, again, very often it is the fly which drives 

 everything before it, as effectually as the descent of 

 the arctic snows. But it is probable that wonderful 

 as these migrations of mighty herds of game animals 

 certainly are, they really, if we look at the matter 

 aright, are far surpassed as curious natural phenomena, 

 by the still more remarkable migrations of birds which 

 literally seem to traverse the broad surface of the earth, 

 by land and sea, from the equator to the poles. 



The migrations of animals can almost always be 

 traced to some self-evident cause, such as the imper- 

 ative necessity for a move, created by some of the 

 causes we have mentioned above ; and in our sections 

 on forest and jungle shooting, and hunting and 

 stalking on plains, we hope to be able to quote a 

 number of striking examples of such cases. But 

 the causes which impel the migrations of birds 

 are much more complex in their origin, so that it is 

 not always easy to assign a reason which accounts 

 satisfactorily for the immense flights periodically un- 

 dertaken by some of these frail and tiny creatures. 



Why should the swallow, for instance, which is seen 

 throughout the winter in the interior of Africa, at the 

 Cape of Good Hope, Australia, New Zealand, etc., 

 suddenly wing its way as far north as Lapland and 

 even to the stormy coasts of the arctic seas? The 



