5 so MIGRATION 



superstitions, and yet we must say of it still that our "ignorance is 

 immense." 



On one point and one only in connexion with this subject 

 can we boast ourselves to be clearly wiser than our ancestors. 

 Some of them fully believed that the seasonal disappearance of the 

 Swallow, the Nightingale, the Cuckow, and the Corncrake was 

 due to what is commonly called " hibernation," that is to say, passing 

 the winter in a torpid condition, while others indeed doubted whether 

 or not this was the true explanation of the fact. It is not so long 

 since this belief and these doubts were in vogue, but now assuredly 

 they have no hold upon the mind of any one capable of appreciat- 

 ing evidence, and this absurd fancy being exploded need not again 

 trouble us. Yet it recurs again and again to those who will not 

 take the trouble to reason, and even to some thinking persons who 

 cannot rid themselves of prejudice. Scarcely a year passes but an 

 instance of this credulity presents itself to the writer, either in some 

 public print or in a private communication. Of the same kind is 

 the equally ancient belief that little birds get themselves conveyed 

 from one country to another by their bigger brethren. Storks and 

 Cranes on their Migration are manifest to beholders, but the transit 

 of lesser birds of feebler flight is seldom evident, and when, as often 

 happens, large and small birds disappear or arrive simultaneously, 

 Avhat is more natural than that the ignorant should suppose that 

 the latter avail themselves of the former as a vehicle 1 Thus in 

 1740 the Tartars of Krasnojarsk and the Assanians assured J. G. 

 Gmelin {Re\&e durch Sihirien, iii. pp. 393, 394) that when autumn 

 came each Crane took a Corncrake on its back and transported it 

 to a warmer land,^ while the well-known belief of the Egyptian 

 peasant that Cranes and Storks bring a living load was not long 

 since gravely promulgated in this country as a truth ! 



In considering the phsenomena of Migration it Avill be best first 

 to take the facts, and then try to, account for their cause or causes. 

 That a very large number of Birds all over the world change their 

 abode according to the season is ■well known, and we find that in 

 all temperate countries there are some species which arrive in spring, 

 remain to breed, and depart in autumn ; others which arrive in 

 autumn, stop for the winter, and depart in spring ; and others 

 again — and these are strictly speaking the " Birds of Passage " — 

 which shew themselves but twice a year, passing through the 

 country without staying long in it, and their transient visits take 

 place about spring and autumn. People who have given but little 

 thought to the subject are apt to suppose that these migrants, 

 which may thus easily be classed in three categories, are acted 

 upon by influences of different kinds, whereas very little reflection 



^ This passage lias been adverted to by Buffon [Hist. Nat. Ois. viii. p. 150) and 

 Pallas [Zoogr. Eoss.-Asiat. ii. p. 153). 



