ox BIRD MIGRATION. 407 



large proportion of them are no doubt the immigrants lately arrived from 

 the north, which, as winter visitors to our islands, remain until compelled 

 to move further south or west. 



The first move on these occasions is to the coast, where some tarry, 

 and even remain to perish ; while others pass down both the east and 

 west coasts of Great Britain, many of those following the former route, 

 sweeping along the south coast westward, and crossing the Channel for 

 the Continent. Many again seek Ireland, from which, however, emigra- 

 tions are also recorded. 



Should the cold spell be of great severity, or be unduly prolonged and 

 widespread, then a still further exodus takes place (observed chiefly on 

 the west coast of Great Britain and east coast of Ireland), and many 

 perish even in such usually safe retreats as the Scilly Isles, and at 

 Valentia, or other isles off the west coast of Ireland, which are largely 

 sought on such occasions. No doubt, too, many of these emigrants perish 

 in their continental haunts, for after winters of almost arctic severity, 

 such as that of 1880-81, ^ the Thrush was conspicuous by its absence, or by 

 its rarity, in most districts in our islands. - 



Spring Immigration. — Among the voluminous records relating to the 

 movements of this species during February, there are many which clearly 

 indicate that the Thrushes which left us in the early autumn to winter in 

 countries to the south of us commence their return to our islands for the 

 spring and summer. 



These immigrations are performed by small parties during mild periods 

 of the month, and are chiefly observed on the southern coasts of England 

 and Ireland. 



Such return movements are continued during the first half of March, 

 when immigrant Thrushes, in company with Blackbirds [Turdus merula). 

 Larks {Alauda arvensis), Pipits [Antkus pratensis), Starlings (Sturnus vul- 

 garis), Lapwings ( Vanelhis vulgaris), and Curlews {Niimenius arqitata), are 

 recorded from the south coast of England northwards to the Western 

 Isles of Scotland, and from the south and south-east coast of Ireland. 



The arrivals on the south coast of England take place during the night 

 or early morning. In Ireland they are recorded for both the hours of 

 darkness and during the daytime, and the birds are noted as proceeding 

 in a north-westerly direction at the south-east stations. 



In most instances the return is a gradual one, performed by small 

 companies, and at intervals, but occasionally in March in ' rushes ' with 

 the other species already mentioned. 



Spring Emigration. — Towards the end of March the Thrushes which 

 have wintered in Tiree and other western islands off the coasts of Scot- 

 land and in Ireland ai'e recorded as taking their departure. 



It is not, however, until April that the spring emigratory movements 

 from the mainland of Britain set in. Then the birds which have 

 wintered in our islands leave our shores to return to their summer 

 haunts in Northern Europe.'^ 



Throughout April, but chiefly during the first three weeks of the 



' During this winter twenty days of hard frost and sixteen days of deep snow 

 prevailed on the west coast of Ireland. It was much more severe elsewhere. 



- Other severe seasons covered by the inquiry, during which great move- 

 ments and much mortality among our Thrushes are recorded, are those of 1885-6 and 

 1887. The first half of March, 1886, was remarkably severe, and many Thrushes 

 perished even in our southern counties. 



^ In 1885, on March 28 and 29, a few Thrushes in company with Blackbirds ap- 

 peared at North Ronaldshay, the most north-easterly island of the Orkneys. 



