HISTORY OF THE SWIFT. 175 
gier invariably withdraws by the twentieth, while their conge- 
ners, all of them, stay till the beginning of October ; many of 
them all through that month, and some occasionally to the be- 
ginning of November.* This early retreat is mysterious and won- 
derful, since that time is often the sweetest season in the year. 
But, what is more extraordinary, they begin to retire still earlier 
in the most southerly parts of Andalusia, where they can be no 
ways influenced by any defect of heat ; or, as one might suppose, 
defect of food. Are they regulated in their motions with us by 
a failure of food, or by a propensity to moulting, or by a disposi- 
tion to rest after so rapid a life, or by what ? This is one of 
those incidents in natural history that not only baffies our 
searches, but almost eludes our guesses ! 
Tliese hirundines never perch on trees or roofs, and so never 
congregate with their congeners. They are fearless while haunt- 
ing their nesting places, and are not to be scared with a gun ; 
and are often beaten down with poles and cudgels as they stoop 
to go under the eaves. Swifts are much infested with those 
pests to the genus called hippohoscce kirundinis; and often wriggle 
and scratch themselves, in their flight, to get rid of that clinging 
annoyance. 
Svydfts are no songsters, and have only one harsh screaming 
note ; yet there are ears to which it is not displeasing, from an 
agreeable association of ideas, since that note never occurs but in 
the most lovely summer weather. 
They never settle on the ground but through accident ; and 
when down can hardly rise, on account of the shortness of their 
legs and the length of their wings ; neither can they walk, but 
only crawl; but they have a strong grasp with their feet, by 
which they cling to walls. Their bodies being flat they can 
enter a very narrow crevice ; and where they cannot pass on their 
bellies they will turn up edgewise. 
The particular formation of the foot discriminates the swift 
from, all the British hirundines ; and indeed from all other known 
birds, the hirundo melba, or great white-bellied swift of Gibraltar, 
* A correspondent of the Magazine of Natural History relates one instance of a swift being 
noticed in Perthshire so late as Nov., 8 ; and I have known them once or twice to occur in Sep- 
tember. So powerful is the migrative impulse in these birds that it is not a very rare occurrence 
for them to leave a young brood of half-fledged nestlings to perish — a fact which has also been 
noticed in others of the swallow tribe. A remarkable instance, however, to the contrary is stated 
in the periodical already mentioned, in which a single swallow was observed to stay for some time 
aftertne departure of its fellows, to attend upon a full grown nestling, the foot of which had beca 
iaexiricably entangled in the nest. — E». 
