558 



MIGRA TION 



of the weatlier.^ This is nob very wonderful, for the movements of 

 the migrants, if governed at all by meteorological forces, must be 

 influenced by their action in the places whence the travellers have 

 come, and therefore to establish any direct relation of cause and 

 effect corresponding observations ought equally to be made in such 

 places, which has seldom been done.- As a rule it would seem as 

 though Birds were not dependent on the weather to any great 

 degree. Occasionally the return of the Swallow or the Nightingale 

 may be somewhat delayed, but most Sea-fowls may be trusted, it is 

 said, as the almanack itself. Were they satellites revolving around 

 this earth, their arrival could hardly be more surely calculated by 

 an astronomer. Foul weather or fair, heat or cold, the PuFFiNS 

 {Fratercula arctica) repair to some of their stations punctually on a 

 given day as if their movements were regulated by clock-work. 

 Whether they have come from far or from near we know not, but 

 other Birds certainly come from a great distance, and yet make their 

 appearance with scarcely less exactness. Nor is the regularity with 

 which certain species disappear much inferior ; every observer 

 knows how abundant the Swift {Cypselus ajpus) is up to the 

 time of its leaving its summer-home — in most parts of England, 

 the first days of August — and how rarely it is seen after that time 

 is past. 



It must be allowed, however, that, with few exceptions, the 

 mass of statistics above spoken of has never been worked up and 

 digested so as to allow proper inferences to be made from them, 

 and therefore it would be premature to say that little would come 

 of it, but the result of those few exceptions is not very encouraging. 

 The most important is due to Dr. von Middendorff who carefully 



1 HeiT Giitke in the valuable work presently to be particularly noticed, 

 attaches much more importance to the effects of weather than I am inclined to 

 do, though I am far from saying that his opinion may not be borne out by his 

 experience on Heligoland, where his observations were made. That is a spot so 

 small that, though exceptionally favoured as a resort for Birds-of-passage, it 

 might easily be missed (as indeed it frequently is) owing to the wind lying in 

 such a quarter as would turn them from their usual com-se. He certainly gives 

 (p. 85) a remarkable instance of a temporarily reversed movemeut in March 1879, 

 doubtless caused by the setting in of bad weather ; but in nearly all cases Birds on 

 their northward Migration do not retrace their flight but persevere in the efforts 

 to get forward, even though \\-lien they reach their goal they may succumb and 

 jierish for want of food through the severity of the season. 



2 To a limited extent it must be admitted that the popular belief as to certain 

 Birds being the harbingers of severe weather is justifiable. Cold comes out of 

 the north, and when it is accompanied, as is most generally the case, by heavy 

 falls of snow, such Birds are of course driven southwards to seek their living. 

 But as often as not the Birds arrive with the kind of weather they are com- 

 monly held to prognosticate, while sometimes this does not follow their 

 ayipearance. 



