156 THE NATURAL HISTORY OF SELBORNE., 
sparrow, which is on the same account a fell adversary to 
house-martins. 
These AZirundines are no songsters, but rather mute, making 
only a little harsh noise when a person approaches their nests. 
They seem not to be of a sociable turn, never with us con- 
gregating with their congeners in the autumn. Undoubtedly 
they breed a second time, like the house-martin and swallow; 
and withdraw about Michaelmas. 
Though in some particular districts they may happen to 
abound, yet in the whole, in the south of England at least, is 
this much the rarest species. For there are few towns or large 
villages but what abound with house-martins; few churches, 
towers, or steeples, but what are haunted by some swifts; scarce 
a hamlet or single cottage-chimney that has not its swallow ; 
while the bank-martins, scattered here and there, live a se- 
questered life among some abrupt sand-hills, and in the banks 
of some few rivers. 
These birds have a peculiar manner of flying; flitting about 
with odd jerks, and vacillations, not unlike the motions of a 
butterfly. Doubtless the flight of all A/zrundines is influenced — 
by, and adapted to, the peculiar sort of insects which furnish 
their food. Hence it would be worth inquiry to examine 
what particular genus of insects affords the principal food of 
each respective species of swallow. 
Notwithstanding what has been advanced above, some few 
sand-martins, I see, haunt the skirts of London, frequenting 
the dirty pools in Saint George’s Fields, and about White- 
chapel. ‘The question is where these build, since there are no 
banks or bold shores in that neighborhood; perhaps they 
nestle in the scaffold holes of some old or new deserted 
building. They dip and wash as they fly sometimes, like the 
house-martin and swallow. 
- Sand-martins differ from their congeners in the diminutive- 
ness of their size, and in their color, which is what is usually 
n 
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