DIRECTION OF THE MIGRATION FLIGHT 37 



migratory impulse, a movement which frequently becomes specially 

 marked with a low and falling barometer ; whereas, on the other 

 hand, what in the above passage he alludes to as the customary 

 migration-course of the birds is in reality a movement of a merely 

 subsidiary character, though in this case one sufficiently powerful 

 to attract notice in a latitude no further south than that of the 

 district referred to. 



We will next proceed to the consideration of the second great 

 movement of the autumn migration, viz. that which proceeds in 

 a direction from north to south. This course of migration is 

 peculiar to a large number of species, more especially such as have 

 their breeding quarters in high northern latitudes, and, in respect 

 to the numbers of individuals taking part in it, fully equals the 

 great east-to-west migration, while, as regards the distance traversed, 

 it in many cases even surpasses the latter movement. 



In proof of a migration proceeding in this direction may be 

 cited many of the Warbler species, that of the Red-spotted Blue- 

 throat being one of the most notable. This bird breeds in high 

 northern latitudes of the Old World from Kamtschatka as far as 

 the central and northern portions of Norway, while its winter 

 quarters range throughout the whole of southern Asia and over 

 the eastern half of north Africa. In Heligoland, as well as in 

 Germany and Italy, it is of quite regular autumn occurrence ; in 

 England, on the other hand, only solitary examples of the bird 

 have ever been met with, and these only at intervals of many 

 years, while in France and Spain it has never been observed at all 

 (Dresser). 



It hence follows most decisively that the bird, in autumn, rigidly 

 adheres to a southerly course of migration, and travels in a broad 

 migration front which corresponds to the longitudinal range of its 

 nesting area, and of which Heligoland forms the most western 

 limit. Even a slight westerly deviation from their southerly course 

 of such species as breed in the west of Norway could not fail to 

 convey large numbers of these birds to the east coast of England, 

 and their all but total absence there furnishes therefore an un- 

 doubted proof of the persistency with which the southerly course 

 of migration is in this instance adhered to. 



Another illustration of the north-to-south migration is furnished 

 by the Red- throated Pipit (Anthus cervinus). This species also 

 breeds in high latitudes from northern Asia to upper Norway, and 

 in its autumn migrations likewise adheres to a most rigid southerly 

 course, since it touches Heligoland only in the most exceptional 

 cases, and has not been shot there more than six times within the 

 last fifty years. Eversmann's Warbler (Sylvia borealis), too, seems 



