376 THE STRUCTURE AND LIFE OF BIRDS chap. 



Exceptional Migrations. 



The Nutcracker, the Waxwing, the Shorelark, 

 Pallas's Sandgrouse occasionally invade Western 

 Europe. The Nutcracker is fond of pine forests, nests 

 in Scandinavia, in the Black Forest and the Alps, and 

 is not as a rule given to wandering. The Waxwing 

 breeds in Arctic regions, and has a way of suddenly, 

 for unknown reasons, forsaking a favourite breeding- 

 ground and moving to another district. Five times 

 during this century, in winter time, it has appeared in 

 Britain in considerable numbers. The Shorelark's 

 summer home is in Northern Scandinavia, Russia and 

 Siberia. In its irregular migrations it sometimes 

 reaches our east coast. Pallas's Sandgrouse lives in 

 summer between the Caspian and Lake Baikal, in 

 winter moves to Northern China, and there has been 

 much speculation as to what caused large hordes to 

 sweep westward in 1863 and 1888. The onward roll 

 of the living wave from place to place on the Conti- 

 nent till at last it reached England excited the 

 curiosity of people for whom, as a rule, the doings of 

 birds have no interest. But in the absence of any 

 facts to help us to explain these weird phenomena, it 

 is well to let the reader's reason or fancy have free 

 play without attempting to guide him. 



Stray Wanderers. 



American birds, as I have said, occasionally visit 

 England, but no return visits are paid by English 

 birds to America. Most of those that come to us are 



