242 THE ZOOLOGIST. 



when this view became established. Herr Gatke has been 

 blamed, but I think without cause. Long before the publication 

 of his well-known work the " head wind" theory was commonly 

 mentioned in British writings, and although nobody pretended to 

 have reasoned observations in its support, and all were ignorant 

 of any natural law that would have made it credible, it continued 

 to flourish. Gatke (believing, of course, that birds did regularly 

 migrate head to wind, and anxious to suggest a reason) said 

 that they did so in order " to escape the disagreeable experience 

 of having the wind blowing obliquely through their plumage 

 from behind" ('Heligoland,' &c, p. 27). Many present-day 

 writers on flight and migration have repeated this curious ex- 

 planation, so comical to the mind of tbe phycisist; and probably 

 the majority of professed ornithologists, if not going so far as 

 Gatke, still believe that a flying bird falls to earth in a "tail 

 wind." 



Few tasks can be more thankless than that of attacking a 

 superstition of science, for it is in human nature that " what did 

 not come in by the door of Eeason, will not be driven out of that 

 door." Apparently, the " Head Wind Theory " was not based 

 originally on actual observations ; I think, however, that its 

 birth was in a misinterpretation of a single common pheno- 

 menon. For example, when a bird crosses the North Sea, under 

 adverse conditions, it comes to earth as soon as it sights land. 

 Now, bird migration is visible, as a rule, only when it ceases to 

 act, and most of our observations are based upon birds that 

 have for some reason or other ceased to migrate, either tem- 

 porarily or permanently. No one would pretend to think that 

 every migrant crossing the North Sea comes to earth the moment 

 it sights land ; only the weaklings, or those destined for that 

 particular locality, become visible to the terrestrial observer, 

 and the main bodies pass overhead in their courses to Cornwall, 

 Wales, or Ireland — to name these destinations at random. 



A head wind, as I shall soon show, is an adverse condition, 

 and birds encountering it are glad to drop to earth, and in 

 this way come to the knowledge of the observer on the coast. 

 Thus the collector or the wildfowler is led quite properly to 

 view a head wind as the one bringing most migrants, and the 

 next step is to believe that birds actually prefer such a wind. 



