SUMMER AND WINTER MIGRANTS 103 



bird than the linnet. Although, as I have re- 

 marked, a certain number of these birds breed 

 annually in Scotland and Ireland, the larger 

 proportion leave us in the spring for the cooler 

 climates of Russia and Scandinavia. When it is 

 considered how apparently little difference exists 

 between some of our winter and summer migrants 

 as regards their covering, it is somewhat puzzling 

 to account for the reason why one bird should 

 prefer a cold climate to a warm and temperate one. 

 The siskin is an instance of this. It is apparently 

 not more warmly clad than the linnet or redpole, 

 yet no sooner is the spring advanced than it 

 leaves us for Russia. The bramble finch is 

 another instance of this peculiarity ; much the 

 same may be observed of the redwing and field- 

 fare. Of course there is a reason why these birds 

 should leave us at the approach of spring, and 

 we may conclude that they elect to migrate at that 

 period partly because the supply of food, such as 

 the berries which are abundant during the winter 

 months, has become exhausted. All the same, 

 there are many seasons in which this description 

 of food is scanty, and therefore more quickly 

 consumed. I do not think that, when such is the 

 case, the migration of these birds takes place at 

 any earlier date than in those years in which it 

 may be more plentiful. 



The redwing, fieldfare, missel-thrush, and, 

 indeed, all the thrushes save one, remain with 

 us throughout the winter. This one exception is 



