166 
THE NATURAL HISTORY 
[LETT. 
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 ; fev/ churches, 
towers, or steeples, but what are haunted by some swifts : scarce 
a hamlet or a single cottage-chimney that has not its swallow ; 
while the bank-martins, scattered here and there, live a seques- 
tered life among some abrupt sand-hills, and in the precipitous 
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 hirundines 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 Whitechapel. 
The question is where these build, since there are no banks or 
bold shores in that neighbourhood : 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 diminutiveness 
of their size, and in their colour, which is what is usually called 
a mouse-colour. ISTear Valencia in Spain, they are taken, says 
Willughby, and sold in the markets for the table ; and are called 
by the country people, probably from their desultory jerking 
manner of flight, Pcqnlion de Montagna. 
Selbgrne, Fth. 2G, 1774. 
