550 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, 
what is more natural than that the ignorant should suppose that 
the latter avail themselves of the former as a vehicle? Thus in 
1740 the Tartars of Krasnojarsk and the Assanians assured J. G. 
Gmelin (Reise durch Sibirien, ii. 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 phenomena of Migration it will 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 
1 This passage has been adverted to by Buffon (Hist. Nat. Ois. viii. p. 150) and 
Pallas (Zoogr. Ross.-Asiat. ii. p. 153). 
