120 THE NATURAL HISTORY OF SELBORNE. 
thirty years past in that part of the world. A mean quantity 
in that county for one year is twenty inches and a half, 
LETTER LA 
FYFIELD, xear ANDOVER, eb. rath, 1771. 
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 swal- 
low kind do not leave us in thé 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 zrundines but of bee-birds, 
hoopoes, or golden thrushes, etc., 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 Bosphorus 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 should 
retreat before the sun as it advances, and retire to milder 
