they purfue the fun into lower latitudes, as fome fuppofe, in order
to enjoy a perpetual fummer, why do they not return bleached ?
Do they not rather perhaps retire to reft for a feafon, and at that
jundture moult and change their feathers, fince all other birds-
are known to moult foon after the feafon of breeding ?
Swifts are very anomalous in many particulars, diffenting from
all their congeners not only in the number of their young, but in
breeding but once in a fummer; whereas all -the other Britifh
hirundines breed invariably twice. It is paft all doubt that fwifts can
breed but once, fince they withdraw in" a fhort time after the flight
of their young, and fome time before their congeners bring out their
fecond broods. We may here remark, that, as fwifts breed but once
in a fummer, and only two at a time, • and the other hirundines
twice, the latter, who lay from four to fix eggs, increafe at an
average five times as faft as the former.
But in nothing are fwifts more Angular than in their early retreat.
They retire, as to the main body of them, by the tenth of Auguft,
and fometimes a few days fooner : and every ftraggler invariably
withdraws by the twentieth, while their congeners, all of them, flay
till the beginning of OBober; many of them all through that
month, and fome occafionally to the beginning of November. This
early retreat is myfterious and wonderful, fince that time is often
the fweeteft feafon in the year. But, what is more extraordinary, they
begin to retire ftill earlier in the moft foutherly parts of Andalujia,
where they can be no ways influenced by any defedfc of heat; or, as
one might fuppofe, defect of food. Are they regulated in their
motions with us by a failure of food, or by a propenfity to moulting,
or by a difpofition to reft after fo rapid a life, or by what ?
This is one of thofe incidents in natural hiftory that not only
Taffies our fearches, but almoft eludes our guefles!
Thefe
Thefe hirundines never perch on trees or roofs, and fo never
congregate with their congeners. They are fearlefs while haunting
their netting places, and are not to be feared with a gun ; and are
often beaten down with poles and cudgels as they ftoop to go under
the eaves. Swifts are much infefted with thofe pefts to the genus
called hippobofc* hirundinis; and often wriggle and fcratch thern-
felves, in their flight, to get rid of that clinging annoyance.
Swifts are no fongfters, and have only one harfh fereamino-
note; yet there are ears to which it is not difpleafing, from an agree”
ablei affectation of ideas, fince that note never occurs but in the
molt lovely fummer weather.
They never fettle on the ground but through accident; and
When down can hardly rife, on account of the fhortnefs of their legs
and the length of their wings : neither can they walk, but only
crawl; but they have a ftrong grafp with their feet, by which they
cling to walls. Their bodies being flat they can enter a very
narrow crevice; and where they cannot pafs on their bellies they
will turn up edgewife. 1
The particular formation of the foot diferiminates the fwiftfrom
all the Britijh hirundines-, and indeed from all other known birds,
the hirundo melba, or great white-bellied fwifi: of Gibraltar, excepted I
for it is fo difpofed as to carry “ omnes quatuor digitos arnicas” all
it s four toes forward; befides the lead toe, which fihould be the
back-toe, confifts of one bone alone, and the other three only of
.two apiece. A conftrudtion moft rare and peculiar, but nicely
adapted to the purpofes in which their feet are employed. This
and fome peculiarities -attending the noftrils and under mandible’
have induced a difeerning h naturalift to fuppofe that this fpecies
might conftitute a genus per fe.
k John Antony Scopoli, of Camiola, M. D.
B b In