140 
NATURAL HISTORY OF SELBORNE. 
Now it is no wonder that birds residing in Africa should re- 
treat before the sun as it advances, and retire to milder regions, 
and especially birds of prey, whose blood being heated with hot 
animal food, are more impatient of a sultry climate : 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, should want to migrate from 
the south of Europe, and be dissatisfied with the winters of An- 
dalusia. 
It does not appear to me that much stress may be laid on the 
difficulty and hazard that birds must run in their migrations, by 
reason of vast oceans, cross winds, &c. ; because, if we reflect, a 
bird may travel from England to the equator without launching 
out and exposing itself to boundless seas, and that by crossing 
the water at Dover, and again at Gibraltar. And I with the more 
confidence advance this obvious remark, because my brother has 
always found that some of his birds, and particularly the swallow 
kind, are very sparing of their pains in crossing the Mediterra- 
nean : for when arrived at Gibraltar, they do not 
" Rang'd in figure wedge their way, 
And set forth 
Their airy caravan high over seas 
Flying, and over lands with mutual wing. 
Easing their flight Milton. 
but scout and hurry along in little detached parties of six or 
seven in a company ; and sweeping low, just over the surface of 
the land and water, direct their course to the opposite continent 
at the narrowest passage they can find. They usually slope 
across the bay to the south-west, and so pass over opposite to 
Tangier, which, it se^ms, is the narrowest space.* 
In former letters we have considered whether it was probable 
that woodcocks in moon-shiny nights cross the German ocean 
from Scandinavia. As a proof that birds of less speed may pass 
that sea, considerable as it is, I shall relate the following inci- 
dent, which, though mentioned to have happened so many years 
ago, was strictly matter of fact :■ — As some people were shooting 
in the parish of Trotton, in the county of Sussex, they killed a 
* It appears probable that many swallows of different species arrive in these islands directly 
from the northern coast of Spain. See an account (by Mr. Couch, of Polperro, an observant 
naturalist), in the fourth volume of the Magazine of Natural History, of a great number being 
seen to land upon the coast of Cornwall, the extreme fatigue of which can only be accounted for 
on the supposition that they had performed so long a journey. These were several times noticed 
to alight flat upon the sea, and, after floating a few miiiutes, to arise again, evidently re- 
freshed. — Ed. 
