278 SPOLIA ZEYLANICA. 
further to the east, and a proportion of the Central European 
migrants turn their course in autumn, not south, but west, 
to find winter quarters in South England and Ireland. Mr. 
Eagle Clarke, when spending a month in autumn at the Kentish 
Knock lightship off the mouth of the Thames, found on the 
same day and hour streams of the same species, such as 
the Skylark, crossing the North Sea in contrary directions. 
Birds from the north which had followed the east coast line 
southward to the Thames were flitting across to the Continent 
from north-west to south-east en route for Southern Europe, 
while at the same time there was a steady stream of birds 
which had come down the Rhine delta from Central Europe 
and were migrating to England from east to west.* 
Many observations have shown that migratory birds do not 
perform their journey “as the crow flies,” but follow certain 
accustomed routes. For many species these routes coalesce, 
for longer or shorter distances, and form favourite fly lines. 
Most birds follow coast lines as far as possible. 
The main fly lines used by migrants to and across the 
British Isles have been worked out, from a multitude of 
records, by Mr. Eagle Clarke, the great British authority on 
the subject. If you look at the map you will see that these 
Islands form as it were a great junction for migratory birds. 
It lies on the migration route of many species which breed in 
Greenland and Iceland on the north-west and in Scandinavia 
on the north-east. Let us examine some of the main routes 
as used in spring. 
The English Channel is crossed at various points. Immi- 
grants to Ireland and many birds on passage to Iceland and 
beyond take the route from Ushant to the Scillies, and from 
thence round the west coast of Ireland. Others, again, make 
their way up the coast of the Irish Sea and on through the 
Hebrides. Birds breeding in England and many Scandinavian 
birds use various crossings between the Ushant-Eddystone 
route on the west and the Straits of Dover on the east. The 
English birds on their arrival slip inland to their breeding 
grounds ; the northerners mainly follow the coast round as 

* «Studies in Bird Migration,” Vol, II., Chap. I. 
