EXCEPTIONAL MIGRATION PHENOMENA 127 



to South America — having even been observed in Europe, but on 

 that occasion only in one sohtary instance. 



If strong westerly winds were the cause of, or exerted an influ- 

 ence upon, the migration of American birds to Europe, as has 

 evidently been assumed to be the case, the Plover just mentioned 

 should be subject to such influences to a far wider extent than any 

 one other species whose home is on the other side of the Atlantic ; 

 for amongst the enormous flocks of these birds which cross that 

 ocean from north to south, one might expect that a violent 

 westerly autumn breeze would in all likelihood drive some one 

 individual or another less robust than the rest across to the 

 shores of Europe. Such however is not the case ; whence the 

 fact of the non-appearance of this Plover in Europe supplies 

 far weightier evidence against the theory of migrants being 

 driven out of their course by storms, than all the known m- 

 stances of the occurrence of strangers have ever furnished in its 

 favour. 



At the time when the question of a possible flight from America 

 to Europe was first mooted, an achievement of this kind appeared 

 utterly beyond the capacity for flight possessed by birds, so far as 

 this was then understood, and consequently was dismissed as im- 

 possible without being even deemed worthy of further investigation. 

 I myself, however, Avas first promjDted by this same question to 

 endeavour to discover a standard of measurement for the velocity 

 of the migration flight, an attempt in which I may claim to 

 have to some extent succeeded. 



Harting still remains very undecided in his opinion on this 

 question. Thus in one place he says that it is extremely hard to 

 believe that birds, other than natatorial species, should have 

 succeeded in crossing the Atlantic, but adds that most of them 

 must nevertheless have accomplished this feat, because, on the one 

 hand, none of them had been met with in Greenland, Iceland, or the 

 Fseroes, and because, on the other hand, many which have occurred 

 in England or Ireland have never been observed anywhere on the 

 continent of Europe. He however considerably weakens his argu- 

 ment when he goes on to say that there was probably good reason 

 for suspecting that many of the smaller of these birds largely 

 availed themselves of the rigging of ships in the course of this 

 passage — overlooking the fact that the hours lost by the birds 

 during such rests only prolong the time which they have to pass 

 without nourishment. The same argument might be urged with 

 equal force in the case of all swimming-birds, belonging to the 

 Anatidce, which might purpose to interrupt their flight across the 

 ocean ; for even if we allow that all such birds are diving Ducks — 

 i.e. Platypeds — which, however, is certainly not the case — the depth 



