372 THE STRUCTURE AND LIFE OF BIRDS chap. 



They have extended their breeding-grounds from 

 Siberia to eastern Europe. But though they have 

 moved their summer residence so far west, in winter 

 they still return to their old haunts in the Malay 

 Archipelago, though Africa is more accessible and, 

 we might imagine, equally suitable. 



When we descend to the details of this part of the 

 subject, it is easy to ask questions which it is impos- 

 sible to answer. For instance, why does the Common 

 Snipe frequently remain to nest in Britain, the Jack 

 Snipe never ? Why do Fieldfares never make our 

 island their nesting-place, while their near relatives 

 the Thrush and the Blackbird are mainly resident here ? 

 The Gray Plover and the Golden Plover present us 

 with a similar problem. In thinking of these diffi- 

 culties we must always bear in mind that there is 

 still much to learn about the lives even of those birds 

 with which we are most familiar 



Hoiv migrants find their way. 



In the whole subject of migration, in many ways 

 so mysterious, there is no such mystery as this. 

 Formerly it was supposed that the old birds guided the 

 young, but it is now known that the young birds start 

 on their adventurous voyage alone, their parents 

 following after an interval. 1 The bachelor birds that 

 migrate early cannot act as guides, since, though they 

 set out about the same time as the young birds, they 



1 Old Bernicle Geese, however, have been seen guiding 

 parties of young on leaving the Hebrides. Gray's Birds of IV. 

 Scotland, p. 349. 



