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OBSEKVATIONS OF AN ATTEMPT OF THE SWALLOW 

 TRIBE TO WINTER IN SOUTH HANTS DURING 



1906-7. 



By Harry Beeston. 



(Concluded from p. 271.) 



If we again refer to the table (ante, p. 270), we see that 

 during the first fortnight of December, with the exception 

 of one day (3rd), favourable winds prevailed, and especially 

 so on the 6th and 7th, when a strong wind from N.E. was 

 in force. Why, I ask, did not the birds depart then? There 

 was not only this advantageous wind to assist the birds on 

 their journey, but there was an additional reason for departure 

 — viz. a very sharp frost on the night of the 6th — yet the birds 

 remained. 



From the 8th to 11th strong cold winds blew, with six degrees 

 of frost on 10th, and seven degrees on 11th ; still the brave birds 

 delayed their departure. From 12th to 18th the weather was 

 fairly open and mild, but day by day, vigorous and strong, the 

 Martins continued to skim up and down stream on the feed. 



A steady breeze from the N.E. prevailed from 19th to 23rd, 

 and again gave the birds a favourable opportunity, but they 

 evidently declined to depart, or their instinct for migration had 

 died out — and so on from day to day they remained ; and it is 

 quite evident that it was neither a wind from the N.E., N.W., nor 

 from any other quarter, for which the birds waited. Strong and 

 persistent breezes were not wanting, both at the latter end of 

 November and the beginning of December. 



We must look for some other reason than mere wind to 

 account for the abnormal departure from the generally accepted 

 ideas regarding the migration of our summer birds. I do not 

 say that wind is not to some extent an important factor, but in 

 my opinion there are other and more potent causes, which largely 

 control the movements of migratory birds. 



