154 THE NATURAL HISTORY 



gnats and other small insects ; and sometimes they are fed 

 with libellulae (dragon-flies) almost as long as themselves. 

 In the last week in June we have seen a row of these sitting 

 on a rail near a great pool as perchers ; and so young and 

 helpless, as easily to be taken by hand : but whether the 

 dams ever feed them on the wing, as swallows and house- 

 martins do, we have never yet been able to determine ; 

 nor do we know whether they pursue and attack birds of 

 prey. 



When thev happen to breed near hedges and enclosures, 

 they are dispossessed of their breeding holes by the house- 

 sparrow, which is on the same account a fell adversary to 

 house-martins. 



These hirundines 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 congregating 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 hirun- 

 dines 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 ot swallow. 



Notwithstanding what has been advanced above, some 

 few sand-martins, I see, haunt the skirts ot London, fre- 

 quenting the dirty pools in Saint George's-Fields, and about 

 White-Chapel. The question is where these build, since 



