NUMBER XXII 

 THE MIGRATION OF BIRDS 



MIGRATION is a regular annual flitting 

 between summer quarters and winter quar- 

 ters, between a breeding or nesting place and a 

 feeding or resting place. And one of the big facts 

 is that birds always nest in the colder area of their 

 migratory range. 



For the Northern Hemisphere bird-migration is 

 the rule, not the exception, but it differs greatly in 

 its range. In many parts of Scotland the curlews 

 pass at the beginning of winter from the exposed 

 moorland to the neighbourhood of the seashore, 

 where it is easier to procure food. This is migration 

 with a short range. It may be contrasted with that 

 of the Arctic tern which the /Scotia explorers found 

 " wintering " in the Antarctic summer in 74 S. lat. 

 the greatest of all known migratory ranges. 



The birds of any country in the Northern Hemi- 

 sphere can be grouped, from the migration point of 

 view, into five sets : 



(1) There are the summer visitors, such as, in 

 Britain, the swallow, swift, cuckoo, nightingale, and 

 so on through the long list (mostly insectivorous, 



144 



