DIRECTION OF THE MIGRATION FLIGHT 35 



According to the English Migration Report for 18S2, this 

 astonishing mass-migration extended through the whole of England 

 across the St. George's Channel to Ireland. It is, however, imjDossible 

 to conceive that all these millions of birds could have wintered in 

 Ireland ; they must accordingly, after reaching the latter country-, 

 have turned on their course southward, and after once more crossing 

 the sea, have landed on the coasts of Spain — a sea passage covering 

 about the same distance as that between southern Sweden and the 

 east coast of England — and accomplished the journey durmg long, 

 pitch-dark October nights, under a sky overcast with dark clouds ; 

 such being the meteorological conditions requisite, at least in 

 Heligoland, for mass-migrations of this character. 



The fact that in more southern latitudes, especially durmg the 

 autumn migration, some species are met with in large numbers at 

 the banks or in the neighbourhood of streams, might at first sight 

 appear to invalidate our conclusions as to migration movements in 

 wide-reaching fronts or columns, and lend support to what is 

 known as the theory of river routes. The explanation of this 

 phenomenon is, however, a very simple one. Districts drained by 

 rivers are generally endowed with a very varied vegetation, and a 

 rich insect life ; consequently the}' are welcomed by the majority 

 of migrants as most desirable feeding-places. All rivers running 

 north or south, from the Ebro to the Lena, are traversed along the 

 greater part of their course by the numberless hosts of migrants 

 travelling westwards in more or less widely extending columns. 

 It is easy to see that they would be used as halting stations by 

 such sections of the migratory host as are in need of rest, food, or 

 water. Consequently one may expect to meet with large numbers, 

 frequently even multitudes of birds, along such river tracts, 

 while on the other hand, in districts remote from streams, on 

 barren moors or over miles of bare and levelled fields, their 

 occurrence would, with the exception of Larks and suchlike species, 

 be extreinely limited. Hence a superficial observation of such 

 phenomena gave rise to the idea that migrants met with in the 

 course of rivers and streams followed the courses of the latter 

 — an idea which to all appearances seems more reasonable than 

 the view that they had reached these quarters by a route crossing 

 this du-ection. 



It is of course quite natural that birds, particularly such as 

 migrate in autumn from north to south, should, imless compelled 

 to hasten their journey, in intermediate latitudes, follow for a time 

 the direction of a stream, or, what amounts to the same, of a valle}', 

 in search of food. This, however, in no way touches the main 

 question of the direction of migration generally. 



