3i8 THE POPULAR SCIENCE MONTHLY. 



unremitting exertion of a flight scarcely less than 100 miles an hour 

 in speed, during the whole of a long summei-'s day, should not be 

 thought capable of the transition from England to Africa. However, 

 at that time it was not well understood what long-continued flight 

 small birds actually do make, as, for instance, from our coast to the 

 Bahamas, or even across to Ireland, or from Egypt to Heligoland, 1,200 

 miles, which is passed over at a single flight by a certain tiny warbler, 

 in every migration. 



The bank-swallow is not a musical bird a faint, squeaking chirrup 

 being all its voice can accomplish. Nor is it a handsome bird, simply 

 sooty-brown above, white beneath, with a brown breast. To its grace 

 of motion, and charming home-life, we attribute that in it which at- 

 tracts us so much. 



Although probably the least numerous of all the swallows, they do 

 not seem so, because of the great companies which are to be seen 

 together wherever they are to be found at all ; and because, leading 

 a more sequestered life, they are not usually brought into direct com- 

 parison with house-martins and chimney-swifts. Eminently social in 

 their habits, they congregate not only at the time of migration (then, 

 indeed, least of all), and in the construction of their homes, but some- 

 times alight in great flocks on the reeds by the river-side and on the 

 beach, where Sir William Jardine saw them "partly resting and wash- 

 ing, and partly feeding on a small fly, which was very abundant." 

 Yet you will occasionally notice stray individuals associating with 

 other swallows. 



The secret of the local distribution of the bank-swallows lies in the 

 presence or absence of vertical exposures of soil suitable for them to 

 penetrate for the burrows, at the inner end of which the nest is placed. 

 Firm sand, with no admixture of pebbles, is preferred, and in such an 

 exposure, be it sea-shore, river-bank, sand-pit, or railway-cutting, the 

 face will be fairly honey-combed with burrows, so that we can readily 

 believe that Mr. Dall counted over VOO holes in one blufi" in Alaska. 

 These are usually very close together, and the wonder is how the birds 

 can distinguish their own doors. If mistakes do occur, I imagine they 

 are very polite about it, for I know of no more peaceable bird than 

 they. The mode in which this perforation, requiring an amount of 

 labor rare among birds, is performed, is well described by Mr. Rennie, 

 in his " Architecture of Birds : " 



" The beak is hard and sharp, and admirably adapted for digging; it is small, 

 we admit, but its shortness adds to its strength, and the bird works .... with 

 its bill shut. This fact our readers may verify by observing their operations 

 early in the morning through an opera-glass, when they begin in the spring to 

 form their excavations. In this way we have seen one of these birds cling with 

 its sharp claws to the face of a sand-bank, and peg in its bill as a miner would 

 his pickaxe, till it had loosened a considerable portion of the hard sand, and 

 tumbled it down among the rubbish below. In these preliminary operations it 

 never makes use of its claws for digging ; indeed, it is impossible that it could, for 



