sist not only of hirundines but of
bee-birds, hoopoes, _Oro pendolos_, or golden thrushes, etc., 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 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
Andalusia.

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, etc.; 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 Mediterranean; 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 seems, is the narrowest
space.

In former letters we have considered whether it was probable that
woodcocks in moonshiny nights cross the German ocean from Scandinavia.
As a proof that birds of less speed may pass that sea, co