CHAPTER XII. 



ON MIGRATION. 



I HAVE already remarked that there is almost always migration 

 going on amongst our feathered tribes, sometimes on a large, but 

 generally on a small scale ; sometimes across the sea and for long 

 distances, but more often from one inland district to another, or 

 from the interior of our island to the sea coast. And the principal 

 motive which impels this so frequent movement, and urges the 

 restless flocks to pass on to pastures new, is not altogether, as 

 many suppose, the inclemency of weather, or the extremes of heat 

 and cold, but the profusion or the scarcity of the food upon 

 which their very being depends. See the countless troops of 

 little warblers which as soon as the warm days of spring waken 

 vegetation, and quicken into life the insect hordes arrive on 

 our shores, and soon spread themselves over this island, revisit- 

 ing each its own old haunt of former years, the. native place 

 where it was reared, maybe ; or mark the vast flocks of birds 

 which, taking leave of us in the spring, penetrate to distant 

 northern lands, there to spend the short but brilliant summer 

 within the Arctic Circle ; and in either case their arrival coincides 

 with the development of countless myriads of insects which are 

 absolutely essential to the very existence of their young. None 

 but those who have visited those northern lands can have any 

 notion of the immense quantities of gnats and mosquitoes which 

 literally cloud the atmosphere ; and, revelling in perpetual sun- 

 shine, with no chills of night to check their increase, they make 

 the most of the few months of continuous daylight, and abound 

 in the greatest profusion. To the unhappy traveller, indeed, 



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