ON BIRD MIGRATION. 109 



3. That the great autumn immigrations from the Continent cease with 

 the month of October, or considerably earlier than those of the Thrush's 

 migratory congeners ; 



4. That winter emigratory movements, clue to climatic pressure, set in 

 with the first severe weather and recur with each outburst, but in gradu- 

 ally diminisliing volume ; 



5. That the return spring immigratory movement of British and Irish 

 Thrushes — summer visitoi's —from Southern Europe, commences in 

 February and continues until the middle of March ; 



6. That the spring emigratory movements— the departures of winter 

 visitors from Britain — for Northern Europe set in and are continued 

 throughout April ; 



7. That the spring birds of passage arrive upon our shores from 

 Southern Europe late in March, and that the passage proceeds during 

 April, and, in some years, extends to the early days of May ; 



8. That the Thrush occurs annually on the British shores from 

 Southern Shetland and Nortli Ronaldshay southwards, and that these 

 stations mark the northern limit of the bird's regular distribution as a 

 migrant in Britain ; 



9. That migrants to and from North-western Europe arrive on, and 

 depart from, our north-eastern and northern coasts, and that many birds 

 of passage among them traverse our eastern and southern coasts on 

 proceeding to their winter quarters (Continental and Irish) in the 

 autumn and on their return in the spring ; 



10. That the autumn immigrants which winter with us reach Western 

 Britain and, to a certain extent, Ireland after an overland passage ; 



11. That the west coast of Britain and the eastern and southern coasts 

 of Ireland are those chiefly visited during the great migratory movements 

 due to severe weather ; 



12. That Ireland is largely sought during the colder months, both by 

 ordinary winter visitors and also by Thrushes driven out of Britain by 

 severe climatic conditions ; 



13. That the Thrush does not participate in the east to west autumn, 

 and west to east spring, movements across the southern waters of the 

 North Sea. 



II. White Wagtail (Motacilla alba). 



The White Wagtail as a British migrant presents several points of 

 interest. 



As a summer visitor it is somewhat rare, and has only been recorded 

 to breed occasionally in some of the more southerly counties of England. 



It is chiefly as a bird of passage that it visits our islands, and is then 

 en route to and from northern breeding haunts which lie both to the N.E. 

 and N.AV. of us, namely, in Scandinavia, Faroe, and Iceland. It occasion- 

 ally reaches Southern Greenland. 



As a migrant it is one of those species, few in number, which are more 

 abundantly and generally observed on our western seaboard and its 

 vicinity than on the east coast. 



Spring Immigration. — The White Wagtail arrives on the south coast of 

 England in small parties during March, sometimes during the early days 

 of that month. ^ 



' The earliest date with which 1 am acquainted relates to this bird's occurrence 

 near Plymouth on March 3, 1872. 



