174 NATURAL HISTORY OF SELBORNE. 



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 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. Near 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, Papilion de Montagna, 



