xxxii INTRODUCTION 



If we go back to Aristotle, the father of natural history, 

 we find that he gives a perfectly rational account of migration 

 in general, including that of birds and fishes. 1 The pheno- 

 mena of migration are indeed sufficiently obvious to the eyes 

 of all observant dwellers on the Mediterranean coasts; and 

 many allusions in ancient literature 2 show that the passage 

 of birds in spring and autumn was familiar to the ordinary 

 Greek and Roman as well as to the learned. But a few pages 

 further on Aristotle goes on to tell us that many birds, and 

 especially those which live at a long distance from warm 

 countries, i.e., in the far north, do not migrate, but "hide 

 themselves " in the cold weather. Many swallows, he says, 

 have been found in the winter so hiding, and entirely without 

 feathers. 3 This, so far as I know, is the first account of the 

 so-called hibernation of birds. 



Remembering that Aristotle was born and bred in a city 

 on the Thracian coast, where he might well hear stories 

 coming from the mountainous region to the north, we may 

 perhaps surmise that in this passage we have an echo of that 

 northern folklore which in more recent times, as will be shown 

 directly, has been the origin of the whole misconception. 

 How far Aristotle himself has been responsible for the spread 

 of this misconception it is impossible to say ; but considering 

 his immense vogue in the middle ages it is not unlikely that 

 his authority added weight to it. In any case it reappeared 

 in literature, and in an exaggerated form, at the close of the 

 middle ages, and so found its way into the writings of English 

 ornithologists. 



Olaus Magnus, Bishop of Upsala in the first half of the 

 sixteenth century, gives an explicit and amusing account of 

 the hibernation of swallows under water ; and in the copy of 

 his work which lies before me 4 there is a quaint woodcut 

 supposed to represent two fishermen extracting the birds from 

 their winter home with a fishing-net. As this account was 

 reproduced not long afterwards by our own Richard Burton 



1 Historia A?timalium < viii., 12. 



2 E.g., Homer, Iliad, iii., 2 ; Virgil, JEneid, vi., 309. 



3 Historia Animalium, viii., 15. 



4 Page 732 of the Basle edition of 1567. 



