The architecture of birds / [Anon].

  • James Rennie
Date:
[1831]
Catalogue details

Licence: Public Domain Mark

Credit: The architecture of birds / [Anon]. Source: Wellcome Collection.

    51/428 page 19
    Head of the Bank-Swallow. when shut. If we compare this little sharp borer, as we may well call it, with the caliper-like mandi- bles of the sand-wasps (Sphecide, Leacu), and of the burrowing bees which, like this swallow, excavate galleries proportionable to their size in hard sand,* we are compelled to confess that the bird is furnished with the more efficient instrument. Its operation also is very different. ‘The insects alluded to gnaw into the sand, or rather bite off a portion of it, and carry it out of the hole in their mouths; but the bank-swallow, as we have had an opportunity of observing, works with its bill shut. This fact otr 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 swallows cling with its sharp claws to the face of a sand-bank, and peg in its bill asa miner would do his pick-axe, till it had loosened a considerable portion of the hard sand and tumbled it down amongst the rubbish below. In these preliminary operations it never makes use of its claws for digging ; indeed, it is impossible it ‘could, for they are indispensable in maintaining its position, at least when it is beginning its hole. We have further remarked that some of this swal- low’s holes are nearly as circular as if they had been planned out with a pair of compasses, while others * See Insect Architecture, chap. iii, &c. + J. R.
    digitised image 1
    digitised image 2
    digitised image 3