DIVING AND FLIGHT 417 



who live on the East Coast of England, and still more to 

 those who reside close to the sea, it must be manifest that 

 the movements of birds are enormously influenced by wind, 

 especially in the autumn, but perhaps less so in the spring. 



All large movements may, in a general sense, be spoken 

 of as migratory movements, but, in fact, birds' movements 

 are divisible into two kinds, viz., those resulting from and 

 dependent upon wind, and those which have no other 

 prompting than the desire — which is inherent in nearly 

 all birds — to seek a warmer climate on the approach of 

 winter, and a colder one on the approach of summer. 

 This proposition is not invalidated by the fact that these 

 two causes not infrequently operate simultaneously. 



Observations taken in Scotland. — Premising this much 

 about the effect of wind upon birds, I will now select from 

 such Gannet data as are available, a few cases which are 

 attributable, in my view, to this cause. For Scotland I 

 cannot do better than quote from the " Reports on the 

 Migration of Birds," where there are many valuable 

 statistics* collected by Scottish lighthouse-keepers for 



* .S'ee " Reports on The Migration of Birds " for 1879,1880, 1881, 1886, in 

 which all the returns for Scotland were tabulated by Mr. Harvie-Brown, 

 who writes: "At Butt of Lewis, the passages of Gannets are noted from 

 the east (when the Stornoway herring season is in full swing), and then 

 also strings and wedges of Gannets fly from N. to S. and are seen 

 approaching the Butt ... to meet the first herring shoals." — H.B. in Hit. 



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