The
swallows and martins are a group of
passerine
birds in the family Hirundinidae which are characterised by
their adaptation to aerial feeding. Swallow is also used in Europe as a
synonym for the
Barn Swallow. This family comprises two subfamilies:
Pseudochelidoninae (the
river martins of the genus Pseudochelidon) and
Hirundininae (all other swallows and martins). Within the
Hirundiniae, the name "martin" tends to be used for the squarer-tailed
species, and the name "swallow" for the more fork-tailed species;
however, there is no scientific distinction between these two groups.[1]It is believed that this family originated in
Africa
as hole-nesters; Africa still has the greatest diversity of species.[1]
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Barn Swallow chicks waiting to be fed |
Tiny heads popping out of the nest |
Description
Swallows have adapted to hunting insects on the wing by developing a
slender streamlined body, and long pointed wings, which allows great
manoeuvrability and endurance.
Like the unrelated
swifts and
nightjars,
which hunt in a similar way, they have short bills, but strong jaws and a
wide gape. Their body length ranges from about 10–24 cm (3.9–9.4 in) and
their weight from about 10–60 g (0.4–2.1 oz). The wings are long, pointed,
and have nine primary feathers. The tail has 12 feathers and may be deeply
forked, somewhat indented, or square-ended. A long tail increases
manoeuvrability, and may also function as a sexual adornment, since the
tail is frequently longer in males. Female
Barn Swallows will select mates on the basis of tail length.
The legs are short, and their feet are designed for perching rather
than walking, as the front toes are partially joined at the base, causing
the bird to display a waddling gait.
The most common hirundine plumage is glossy dark blue or green above
and plain or streaked underparts, often white or rufous. Species which
burrow or
live in dry or mountainous areas are often unglossed brown above (eg
Sand Martin and
Crag Martin). The sexes show no, or only limited,
sexual dimorphism, with longer outer tail feathers in the adult male
probably being the commonest distinction where one exists.
The chicks hatch naked and with closed eyes. Fledged juveniles usually
appear as duller versions of the adult.
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