THE MIGRATION OF BIRDS 5 



summer range either in an easterly or westerly direction. 

 The Arctic Willow Wren and the Eustic Bunting, on the one 

 hand, do not know of Africa ; the Eed-footed Falcon, on the 

 other, is ignorant of the groves and plains and perpetual 

 summer of India ! A still more extraordinary instance is to 

 be found in the Arctic Tern. This bird is found in summer 

 right round the polar basin, having spread east and west from 

 the shores of the Atlantic ; but in autumn the birds that have 

 actually bred on the shores of the Pacific come back again 

 over thousands of miles of land and water, across the con- 

 tinents of Asia and North America to the southern portions 

 of the Atlantic to spend the winter — being ignorant of the 

 fact that the Southern Pacific is just as suitable to their 

 wants ! This persistence in following an old familiar route, 

 and in seeking the usual winter home, must cause the death 

 of many birds every season. Birds are apt to lose their way 

 just as human travellers do, and take the wrong route which 

 brings them to lands where they are looked upon as great 

 rarities. Many such birds visit our country from time to 

 time in spring and autumn. In spring the migration is 

 almost universally from south to north ; and such birds as 

 lioUers, Bee-Eaters, White Herons, and Vultures occasionally 

 come too far and wander to Great Britain with the stream of 

 our accustomed migrants. In autumn the course is from 

 north to south in the majority of instances ; but there is a 

 considerable migration from east to west at this season, which 

 sometimes brings us such distinguished visitors as the JSTeedle- 

 tailed Swift, the White-winged Lark, and the Yellow-browed 

 W^arbler — strangers from Siberian steppes and forests, which 

 have lost their way and joined the throng of birds whose 

 usual course lies in this direction. 



Birds choose many different highways in their journeys 

 to and fro. Some follow coast-lines, others start boldly across 

 the sea ; many journey down great river valleys, or through 



