THE PHILOSOPHY OF MIGRATION. 77 



migration time, if necessity demands a high rate of 

 speed and a short time for transit. The Dotterel 

 {Eudromias morinellus) breeds on the tundras of 

 Arctic Euro-Asia, and winters in Africa, north of 

 the Equator. Its spring migration is late and 

 rapid, and as the bird is scarcely ever seen in inter- 

 mediate localities during this season (Heligoland 

 records but few in May), we are forced to the con- 

 clusion that this enormous flight of quite 2000 

 miles is performed without a rest, and between 

 sunset and sunrise. If the Dotterel were to start in 

 the evening gloom from its African haunts, say at 

 seven, it would reach the moors of the Arctic 

 regions, by flying 200 miles per hour, about Ave 

 the following morning — a record of speed that 

 makes the highest pace of our " Flying Scotch- 

 man," " Wild Irishman," or " Dutchman " appear 

 but the creep of a snail by comparison, and of 

 astounding endurance, which may well fill us with 

 genuine admiration and wonder. As is usual, the 

 flight is slower in autumn, and then the Dotterel is 

 observed on passage in the ordinary way, crossing 

 Heligoland in August, passing through Germany 

 in September, and Malta in October and November, 

 but always very rare over the British Islands at that 

 season. 



Equally interesting, and perhaps even more im- 

 portant than the Velocity of flight, is the Altitude 

 at which it is performed. In my opinion, the vast 

 importance of altitude in migration has never been 

 recognized by naturalists. I will even go so far as 



