THE MIGRATION OF BIRDS 



tired and feeble after their long pilgrimage. Sometimes in 

 autumn migratory birds appear in unwonted numbers, having 

 been detained by contrary winds or rough weather till the 

 flocks assumed enormous dimensions — all waiting for the 

 first favourable moment when the journey can be resumed. 

 Many birds, eminently solitary in their habits at all other 

 times, become gregarious or sociable during the periods of 

 mio-ration. Hawks and Falcons often unite into flocks to 



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migrate ; so do Woodcocks, Snipes, and Owls. 



Migration is of many kinds, and almost every species of 

 bird is subject to its influence more or less. In some countries 

 the great migration takes place to and from the mountains to 

 the plains ; in others many birds journey from the coasts to 

 inland districts, or from the wide ocean to the land, or from 

 the woods to more open localities. This may readily be 

 observed, even in our own land. The Meadow Pipit and the 

 Twite migrate from mountain to lowland according to season ; 

 the Dunlin and the Golden Plover may be cited as instances 

 of birds migrating from the coast to inland moors ; the 

 Guillemot and Puffin, the Gannet and Cormorant, from the 

 sea to the rocks and islands. Even such birds as the Black- 

 bird and the Eobin change their ground a good deal with the 

 changing season ; and most other species do the same. 

 Some species that are regular migrants in the north of 

 Scotland are residents in the milder climate of England. 

 Birds too are very apt to increase their range if circum- 

 stances are favourable. The Rook is gradually spreading 

 northwards and westwards with the planting of trees ; so 

 too is the Missel-Thrush ; and as many wild districts come 

 under the reclaimino: hands of the aoriculturist, various 

 smaller birds increase their range, at the expense of their 

 shyer and larger congeners, to whom reclamation and im- 

 provement from man's point of view means banishment and 

 ruin from theirs. Excess of population also causes birds 



