6 STUlilJS, The Use of Wind by Migrating Birds. 



result of the pressure distribution, but the very converse 

 is the case. These parts are still further weakened by 

 the separation of the portions headed Meteoj'ological {i.e. 

 Barometric conditions) and Winds. The author seems to 

 ignore the close connection between the two. Another 

 passage may be given here (p. 476) " There is really no 

 reason why westerly (west, north-west, or south-west) 

 winds, not too strong of course, should not, other things 

 being equal, be in every way as suitable for migratory 

 movements [westwards across the North Sea] as those 

 varying between such divergent points as north-east to 

 south." Then follows the passage I have already quoted 

 on the flight of Gulls. From what I have already 

 explained it will be seen that I cannot in the least accept 

 the suggestion. 



Winds do not, in this part of Europe, move in straight 

 lines. They come to us, especially in autumn, in a curved 

 line from the Equator over the Atlantic, in a series of 

 huge eddies or " cyclones," laden with a mass of water 

 vapour, and, I now suggest, bearing at migration times a 

 horde of birds. A cloud to-day lying over Norway may 

 be trailing to-morrow over Manchester, and the next day 

 over the south of France. I believe that birds habitually 

 make use of these cyclones as a means of travelling from 

 one part of their range to another under the most 

 favourable conditions for the exercise of flight. It is clear 

 to mc that a bird, unless it possessed power of flight 

 sufficient to make it somewhat independent of wind, 

 would have great difficulty in struggling across the 

 concentric currents of a cyclone. This aspect of the wind 

 seems never to have been studied by the holders of the 

 " Head-wind " or " Beam-wind " theory, but I have 

 recently come across a passage in Mr. Abel Chapman's 

 " Wild Norway " (p. 339) that leaves little doubt that he has 



