140 



forgets, that he has himself called especial attention to the fact 

 that this species is one of the most powerful fliers known. A 

 biird which can maintain a speed of over 200 miles an hour for a 

 long period, would hardly be likely to be blown very far out of its 

 course by the most violent of gales. Two other species, Larus 

 Sabinii and Eossi are included in his American list of Heligoland 

 captures, though so little is known of their breeding grounds. 

 Eecently, however, Nansen has met with the latter in some 

 numbers in Franz Joseph Land, thiis rendering it improbable that 

 the Hehgoland example may have come from America at all. 



In the light of the evidence discussed in the present and fore- 

 going chapters, it seems very hazardous to assert the opinion 

 that the migrations or wanderings of any species are strictly 

 confined to a rigidly mapped out route. Probably every bird 

 goes its own way. Those huge assemblages which pass parti- 

 cular points result from the fact that the path of many in reach- 

 ing certain localities is for a long distance identical. Every 

 species, nay every little clan of birds has its own migratory 

 history, resembling as a whole the story of the common flight, 

 but on the other hand differing at many points in its minor 

 • details. So far from being characterised by a flight in two main 

 directions, the route followed will be partially governed by the 

 relative positions of breeding grounds and winter quarters, and 

 the time honoured paths by which the travelling hosts have for 

 unknown ages passed from one to the other. Even in the light 

 of Herr Gatke's theories the simple east to west autumnal flight 

 has at some point to be supplemented by a turn to the south or 

 south-west, and again the course of the north and south journey 

 in the countries lying towards the head of the Mediterranean 

 Sea, gives way to a flight from north-west to south-east. 



