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ON THE MIGRATION OF BIRDS. 455 
arrive on the east shores of Britain at points between the Shetland Isles 
and the Humber or the northern seaboard of Norfolk. All the move- 
ments do not necessarily cover this extensive stretch of coast-line, but such 
is not infrequently the case. Indeed, as a rule, they are recorded from 
the greater part of the region indicated. It is possible to define the 
southern limit on the coast at which these birds strike Britain, with a 
considerable degree of precision. No section of the British coast is so 
well equipped with light-stations as that which lies between the north 
coast of Norfolk and Dungeness. In addition to an average number of 
lighthouses, there is a fleet of lightships off the coast, which are most 
favourably situated for recording the movements of birds crossing the 
North Sea to the English coast. These lightships have furnished the 
Committee with some of the most carefully kept records to be found 
among the returns, and it is a very significant fact that these great 
autumn immigratory movements are not observed at these south-eastern 
lighthouses and lightships. Evidence of a particularly important nature, 
in this connection, is also afforded by the records kept at the Outer Dow- 
sing Lightship, the most isolated of the stations in the North Sea, situated 
about 38 miles E.S.E. of the mouth of the Humber. At this station these 
important movements are not observed—another significant fact, indicat- 
ing unmistakably that these migrants pass to the northward or westward 
of this Lightship. 
The conclusion at which I have arrived, after a long and careful study 
of the records, is that these immigrants and emigrants from and to 
Northern Europe pass and repass between this portion of the Continent 
and Britain by crossing the North Sea in autumn in a south-westerly 
direction, and in spring in a north-easterly one,! and that, while the limit 
to their flight in the north is the Shetland Islands, that on the south ex- 
tends to the coast of Norfolk.2 During these movements the more 
southern portion of the east coast of England is reached after the arrival 
of the immigrants on the more northern portions. 
It is to be remarked, also, as bearing upon this important point, that 
all the species occur on migration in the Orkney and Shetland Islands, 
but not in the Feroes.? And, further, a// the British birds of passage to 
Northern Europe are either summer visitors to Scandinavia or are regular 
migrants along the western shores of that peninsula. 
After arriving on our eastern shores, these immigrants from the 
north—some of them after resting for a while—move either down the 
east coast, en route for more southern winter quarters, or, if winter 
visitors, to their accustomed haunts in Britain and Ireland. A few occur 
as birds of passage on the west coast and in Ireland, which they reach 
by overland routes across Britain, and then pass southwards to their 
winter quarters. The west coasts, however, do not receive directly any 
immigrants from Continental Europe. 
Intermigration between the South-east Coast of England and the Coast 
1 The direction varies. It is probably more westerly (in autumn) or easterly (in 
spring) at the most northern British stations, and south-south-westerly (in autumn) 
or north-north-easterly (in spring) at the stations on the east coast of England. 
2 The formation adopted by the migrants during passage would seem to be an 
extended line—perhaps a series of lines—whose right wing extends to the Northern 
Islands and its left wing to the coast of Norfolk. 
% A few species occur in the Feroes on migration, but these are also summer 
visitors to those islands and to Iceland. 
