170 NATURAL HISTORY 



only a little harsh noise when a person approaches their nests. 

 They seem not to be of a sociable turn, never with us congre- 

 gating 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 sequestered 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 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 group 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 Georges-Fields, and about White- 

 Chapel. 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 build- 

 ing. 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 colour, which is what is usually 

 called a mouse-colour. Near Valencia in Spain, they are 

 taken, says Willugliby, and sold in the markets for the table ; 

 and are called by the country people, probably from their 

 desultory jerking manner of flight, Papilion de Montagna. 



