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 diff- 
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 
How 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 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 W. 
Scotland, p. 349. 
