38 



land,' to an inter-migration 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 riiost 

 obligingly communicated details of the bird movements observed 

 on Heligoland for four years (1883-1886), during which the in- 

 quiry was being prosecuted over the British area. These two 

 sets of data have been carefully 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 regularly, often indeed in 

 ' rushes ' at the more' favoured 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. An thus Eichardi, &c., while species common to 

 both islands occurs in ' flights like clouds,' in ' hundreds of 

 thousands, ' thousands upon thousands,' in ' marvellous numbers,' 

 ' astonishing flights,' and 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 com- 

 pels the investigator to come to the conclusion that Heligoland 

 and Britain draw their migratory hosts from different sources." 

 Mr. J. H. Gurney has been at some considerable pains in 

 drawing up a comparative list of the occurrences of certain species 

 which have arrived at various times on Heligoland and on our 

 east coasts in exceptional numbers, and whilst the result might 

 appear to some extent to confirm the view that a close connection 

 exists between the migratory streams affecting both locaUties, stUl 

 he does not fail to point out that in the greater number of in- 

 stances there is no connection whatever. Mr. W. Eagle Clarke 

 further expresses the opinion that as " the ordinary movements 

 of any common raigratory bird occur in each month of its 

 seasonal flight-periods, and the mere coincidence of the species 

 being observed simultaneously in ordinary nwmhers on both sides 

 of the North Sea, has no significance whatever. It is not im- 

 possible or improbable that birds may occasionally cross the 

 German Ocean by an east-to-west flight in the latitude of 



