Page:Popular Science Monthly Volume 7.djvu/332

318 unremitting exertion of a flight scarcely less than 100 miles an hour in speed, during the whole of a long summer'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 attracts 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 comparison 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 sometimes alight in great flocks on the reeds by the river-side and on the beach, where Sir William Jardine saw them "partly resting and washing, 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 700 holes in one bluff 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:"