272 AUTUMN AND WINTER 



part of the garden or by the back door. One great route 

 of migration in autumn runs from the west of England 

 through southern Ireland or north-western France, and 

 thence to the sunny coastal districts of Spain and Portugal, 

 where many birds from northern Europe find a winter home. 

 Two plovers marked in the nest near Stirling have been 

 found in Portugal, and five others in Ireland ; a song-thrush 

 from Aberdeen and a black-headed gull from Argyllshire 

 were also found in Portugal. But in spite of these and other 

 instances showing the importance of this route, other birds 

 of the same kinds have been found in winter not many miles 

 from their nesting-quarters. In the case of many of the 

 hardier birds, the migratory movement is plainly very 

 irregular, and may be regarded as almost optional. Some- 

 times they are even found migrating the wrong way, that 

 is, towards the colder quarter. A song-thrush marked in 

 Berkshire in April was found in November near Norwich 

 — having migrated in exactly the opposite direction to 

 thousands of thrushes, and larks, and plovers, and rooks, and 

 many other kinds of birds which come over from Germany to 

 England at that time. Even more striking was the eastward 

 journey of a starling marked in Berkshire in February, which 

 was found in Kent before the end of the month. Because 

 the east of Europe is colder in winter than the west, the 

 usual line of autumn and winter migration is south-westerly, 

 and sometimes even north-westerly, and not, as might be 

 thought, direct from north to south. 



To a considerable extent — exactly how much we cannot 

 yet tell— migrating birds follow definite routes, such as a 

 river valley like that of the Thames as it leads northwards 

 past Oxford, or the line of the seashore. The rarity of 

 certain birds of double passage in spring as compared with 

 autumn, or vice versa, indicates that they do not all follow 



