MIGRATION OF BIRDS. 279 
far as the Humber, where they begin to cross the North Sea. 
Few leave our shores before they reach this point in their 
northward journey. Many hold right on till they come to 
the Orkneys and Shetlands. Others, again, such as the 
Swallows, cross the North Sea at various points between the 
Humber and the north coast of Scotland. 
From the Shetlands there are two main streams: one 
north-west to Iceland, meeting the Irish and Hebridean routes 
at the Faroes ; and one north-east to the mainland of Norway. 
In autumn the process is reversed. 
From observations on the Continent and in America we find 
that there also there are favourite fly lines ; river valleys and 
coast lines are greatly followed. For instance, from South- 
west Europe there is a main route up the Rhone Valley and 
down the Rhine, while in the United States the Mississippi 
Valley is a much-used route. 
It is interesting to note that for some species the spring 
route is not the same as that taken in autumn. This is 
especially well shown in the case of the American Golden 
Plover, Charadrius dominicus, whose routes have been care- 
fully worked out by an American ornithologist.* This bird 
breeds in Arctic North America, from Alaska to Hudson’s 
Bay. In autumn the flocks move south-east to Labrador, 
where the autumn berries give them abundant food. After 
a short stay there, they move on to Nova Scotia, and then 
cross the sea by a long journey southwards to the north-east 
coast of South America. It is probable that this direct sea 
route is the evolution of a longer coastal journey down the 
eastern shores of the States and round the Caribbean. On 
arrival on the Guiana coast the birds rest for a short time, 
then cross Brazil to winter quarters, mainly in the Argentine. 
The return journey in spring is more directly northwards, 
probably because the spring moves northwards earlier on the 
western side of the States than on the bleaker Atlantic coast. 
The route lies across Bolivia, through Central America, to 
Texas, thence up the great fly line of the Mississippi and over 
Western Canada. 


* Vide Coward, “‘ Migrations of Birds,” p. 77, &e. 

