120 



THE NATURAL HISTORY 



[I.RTT. 



LETTER XLII. 



TO THE HONOURABLE DAIXES BARRIXGTOK. 



You are, I know, no great friend to migration ; and the well- 

 attested accounts from various parts of the kingdom seem to 

 justify you in your suspicions, that at least many of the swallow 

 kind do not leave us in the winter, but lay themselves up like 

 insects and bats, in a torpid state, and slumber away the more 

 uncomfortable months till the return of the sun and fine weather 

 awakens them. 



But then we must not, I think, deny migration in general ; 

 because migration certainly does subsist in some places, as my 

 brother in Andalusia has fully informed me. Of the motions 

 of these birds he has ocular demonstration, for many weeks 

 together, both spring and fall : during which periods myriads of 

 the swallow kind traverse the Straits from north to south, and 

 from south to north, according to the season ; and these vast 

 migrations consist not only of hirnndincs, but of bee-birds, 

 hoopoes, Oro pendolos, or golden thrushes, &c. &c., and also of 

 many of our soft-billed summer birds of passage ; and moreover 

 of birds which never leave us, such as all the various sorts 

 of hawks and kites. Old Belon, two hundred years ago, gives 

 a curious account of the incredible armies of hawks and kites 

 which he saw in the spring-time traversing the Thracian Bos- 

 porus from Asia to Europe. Besides the above-mentioned, 

 he remarks that the procession is swelled by whole troops of 

 eagles and vultures. 



Now it is no wonder that birds residing in Africa, and 

 especially birds of prey whose blood being heated with hot 

 animal food are more impatient of a sultry climate, should 

 retreat before the sun as it advances, and retire to milder 

 regions; but then I cannot help wondering why kites and 

 hawks, and such hardy birds as are known to defy all the 

 severity of England, and even of Sweden and all north Europe, 



