ON THE MIGRATION OF BIRDS. 457 
southerly and westerly journeys were performed. Thus in the spring 
these birds depart from the same sections of our eastern seaboard as 
witnessed their arrival in the autumn. 
Intermigration between Heligoland and Britain.—Much prominence 
has been given in some of the Annual Reports issued by the Committee, 
and in Herr Gatke’s book, ‘ Die Vogelwarte Helgoland,’ to an intermigra~ 
tion between Heligoland and the east coast of England by a direct east-to- 
west autumn, and it is to be presumed west- to- east spring, movement. 
Herr Gatke most obligingly communicated the details of the bird- 
movements observed on Heligoland for four of the years (1883-1886) 
during which the inquiry was being prosecuted over the British area. 
These two sets of data have been carefull y examined and compared, and 
it has been found that the dates of the chief movements of the species 
common to Heligoland and Eastern Britain seldom if ever correspond, and 
do not bear out this theory ; that particular species which are irregular as 
migrants in Britain, such as the Ortolan Bunting, and others, occur regu- 
larly, often indeed in ‘rushes,’ at the more fav ured. isle off the mouth of 
the Elbe ; that other species, which are very rare on our British shores, 
occur in Heligoland as regular migrants and in considerable numbers, as, 
Motacilla flava, Anthus Richardi, &c.; while species common to both 
islands occur in ‘flights like clouds,’ in ‘hundreds of thousands,’ ‘ thou- 
sands upon thousands,’ in ‘marvellous numbers,’ ‘astonishing flights,’ ancl 
so on, at Heligoland, at periods when there is not a single observation for 
the same species on the English shores. A study of the phenomena of 
migration at the stations on the east and west sides of the North Sea 
compels the investigator to come to the conclusion that Heligoland and 
Britain draw their migratory hosts from different sources. The ordinary 
movements of any common migratory bird occur in each month of its. 
seasonal flight-periods, and the mere coincidence of the species being ob- 
served simultaneously i in ordinary numbers on both sides of the North Sea 
has no significance whatever. It is not impossible or improbable that 
birds may , occasionally cross the German Ocean by an east-to-west flight. 
in the latitude of Heligoland, but our data lead us to believe that such 
cases are the rare exception and not the rule. 
Intermigration between Britain and Feroes, I celand, and Greenland.— 
The Froes, Iceland, and Greenland are the summer home of several Pale- 
arctic species which occur as birds of passage on the British coasts. The 
majority of these visit Iceland, and Greenland claims only two or three of 
them (Wheatear, White Wagtail, and Whimbrel). It is natural that these 
birds being of strictly Old World species, our Islands should le in the 
course of their migrations. It is quite possible that these migrants may 
pass along both the eastern and western coasts of Britain and the coasts 
of Ireland. Here, at any rate, we have evidence that these birds are ob- 
served on passage on our western shores. It may be that some of the 
birds proceed also along our eastern seaboard, but this is a point difficult: 
to determine. There is good evidence, however, that important move- 
ments of Redwings, Wheatears, and Whimbrels are observed on the west- 
ern coast of Great Britain and the Irish coasts (both east and west as 
regards the passage of the Whimbrel), which are not observed elsewhere. 
Such a fact points to the independent nature of these west coast flights, 
and indicates that, in some instances at least, the western route alone is 
followed. 
It is thus evident that, so far as concerns the movements of the birds 
