iOO MIGRATION. 



will fairly allow for the time occupied by the hen-birds for incubation, as 

 the summer day is sometimes seventeen hours of direct light, in which 

 a continual stir takes place. Then there are the Willow-wren3, White- 

 throats, Wheatears, Blackcaps, and we know what indefatigable gentlemen 

 the Flycatchers are, all these being purely insectivorous, and the first and 

 last, perpetually in very active search of prey, scarcely still for a moment; 

 and, besides all these, there are our own birds, which, more or less, make it 

 their chief article of food. Only reflect, if it were not for this drain, what 

 myriads of insects would infest every part of our dwellings, our clothes, and 

 furniture; the whole air itself would teem with them, as it does sometimes, 

 even as it is, and we should be as it were eaten up piecemeal. Are not 

 therefore these little feathered creatures extremely useful members of the 

 community? indeed they are, and we must admit that they cheer us by 

 their song, and enliven us by their presence also. As they perform the 

 process of nesting here, their numbers when they depart are increased nearly 

 four-fold at a reasonable computation, more particularly as some have two 

 broods; and yet such is the wonderful balance which is kept in this mi- 

 raculous scheme of creation, that the difficulties and dangers which they 

 undergo in their journeys to and fro, so lessen their numbers as usually 

 to bring them very near even again; indeed some most accurate natural 

 observers have declared positively that as far as observations went or could 

 go, with regard to particular kinds of summer birds, whose motions were 

 easily watched, the same exact number of pairs returned to the same spots 

 to breed annually. Now is not this astonishing? it may be considered 

 almost a miracle, and yet look at our own bills of mortality, and I think 

 we shall not be able to deny that it is a parallel case. 



The ancients had the most singular and improbable notions with regard 

 to the subject of migration, one of which was, that as the winter 

 approached, Swallows went "under water," and there remained in a torpid 

 state until spring. Another was that they hid in hollow trees and the 

 holes and crannies of rocks, and in Stillingfleet's "Swedish Calendar of 

 Flora," published in 17G1, there is an entry made by Linnaeus himself, 

 thus, "Swallow goes under water!" It is, however, some excuse for our 

 forefathers, that not only was natural science in its infancy, but naturalists 

 of much later periods have been sceptical (I will not say absurd) enough 

 to entertain the same opinion, though in a doubtful manner. This was a 

 particular hobby of Gilbert White's, the Selborne historian, and I believe 

 he died without having satisfied himself; but there have been such 

 decided proofs of actual migration, that no doubt whatever can exist. Mr. 

 Adamson, in his "Voyage to Senegal," says that in October, 1749, 

 European Swallows settled on the rigging of the vessel in which he was, 

 and they are never seen at Senegal or Goree but at that time of the year, 



