The SWALLOWS (Hirundines) constitute the foremost family of this order,
and are readily distinguished by their small, delicately-formed body,
broad breast, short neck, and flat head; their beak is short, flat, broad
at its base, and terminates in a slight hook; the gape is so wide as to
extend as far as the eyes. These birds have no crop; their broad, flat,
horny tongue is sharp at its edge, divided at its tip, and furnished with
small tooth-like appendages towards its base. The feet are broad and
feeble, the toes, three of which are placed in front, are very weak and
the claws are slender. The wing is long, narrow, composed of nine quills,
and sharply-pointed at its extremity; the tail forked, containing twelve
feathers; those at the exterior often far exceeding the centre ones in
length. The plumage is composed of small compact feathers, and frequently
exhibits considerable metallic lustre. Both sexes are alike in colour,
but the young differ somewhat from the adult birds.
Swallows are found throughout every division of both hemispheres, and
occupying every latitude, but they rarely breed and are far from numerous
within the limits of the Polar regions. Such species as inhabit the
torrid zones do not migrate, whilst those that visit comparatively
cold countries go to warmer climes as winter approaches, quitting and
returning to their native lands at the appointed period with such
extraordinary regularity that the time of their appearance or departure
may be calculated almost to a day. As regards their intelligence, these
birds are far superior to most other members of the order. Their pleasing
twitter may almost be termed a song, and their flight is distinguishable
by an ease and rapidity that has rendered it proverbial. All Swallows
bathe and drink whilst upon the wing. They subsist upon insect diet,
which they obtain by darting upon their tiny victims with marvellous
velocity as they skim through the air, and swallow them entire. They
consume beetles and flies in enormous quantities, for their appetite
is insatiable; but bees and wasps, or any insect armed with a sting,
they never touch, as their wonderful instinct renders them fully aware
that such morsels are not to be snapped at with impunity. Naumann
mentions that having upon one occasion put a wasp into the beak of a
young Swallow, the bird died almost immediately from the effects of the
stinging it received whilst swallowing the insect. Some species form most
artistic abodes with bits of clay consolidated by means of the glutinous
spittle with which the members of this family are provided; whilst others
excavate deep holes for the reception of the young, the same nests being
employed for many successive years. The females alone brood, and lay from
two to six eggs.
[Illustration: THE CHIMNEY SWALLOW (_Cecropis-Hirundo-rustica_).]
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The TRUE SWALLOWS (_Cecropis_) are characterised by their slender and
powerful body, wide flat head, broad but very slightly curved beak, long
wings, extending beyond the deeply-forked tail, moderate sized foot, and
lax plumage, which upon the upper parts gleams more or less with metallic
lustre.