154 RURAL BIRD LIFE. 



Britain he will, supposing him to have some little know- 

 ledge of ornithology, perhaps notice that but very {^\^ 

 species are perfectly stationary. The major part, then, 

 are of more or less migratory habits. Some migrate to 

 distant countries for the purpose of rearing their young ; 

 others, though their young are reared around us, still 

 with unerring certainty leave our shores in the autumn 

 months. Many visit us for a short time in the winter, 

 to escape the inclement elements in their northern 

 haunts ; while yet again numbers only visit us at inter- 

 vals long and far between, but for what purpose we are 

 as yet in ignorance. Probably the spring migration of 

 birds is performed for the purpose of rearing their off- 

 spring in places specially adapted to the purpose, while 

 the autumn movements are chiefly influenced by the 

 supply of food and the state of the elements. But in 

 the case of the Tree Pipit and many other species these 

 remarks will scarcely apply. We must, therefore, view 

 the migrations of many species as requisite to the pre- 

 servation of the balance of Nature and the equal distri- 

 bution of the feathered tribes throughout the earth. 



Thus in the far north the elements and scarcity of food 

 drive all, or nearly all, species to temperate climes, 

 where they can spend their winter in comparative ease 

 and safety. But it will be seen that did no birds 

 migrate from temperate climes, as our own for instance, 

 birds would be far too abundant and unequally dis- 

 tributed. Therefore, as if to balance this great influx 

 of birds fleeing from the rigid winter of the north, many 

 birds in temperate climes retire still further south, to 

 regions where an opposite season prevails to that of the 

 country left, and where the presence of birds is needful. 

 In the spring the northern birds retire northwards, and 

 the temperate birds leave their southern haunts, now 



