The SOCIAL WEAVER BIRD (_Philetaërus socius_) stands alone in the
peculiarities that distinguish it from its congeners. This species
is recognisable by its conical and elongated beak, which is somewhat
compressed at the sides; its upper mandible rises into a slight arch, and
is furnished at its edges with a tooth-like appendage; the wings are of
moderate length, scarcely extending beyond the root of the tail: their
first quill is much shorter than the succeeding four, which are of equal
length; the tail is rounded at its extremity. In this species, as in the
whole family of Weaver Birds, the tarsus is strong and high. The plumage
is extremely simple: the top of the head, sides, and front of the neck
and breast are of uniform deep grey; the upper part of the head marked
with dark spots; the nape and back grey, with undulating lines of black;
the wing-covers, quills, and tail-feathers deep brown, edged with light
grey; the feathers on the sides of the belly are blackish, bordered with
a paler shade; the region of the beak and a small spot over each eye are
black; and the beak and legs horn colour. Its length is about six inches
and nine lines, and the wing measures rather more than two inches and ten
lines. The female is known by the paler colour of the back, and the young
by the brown tints upon the head; the latter are without the black spot
upon the lower mandible and sides of the body.
It is generally considered that the Social Weaver Bird never crosses the
Orange river, though how far it may penetrate in a northerly direction
has not as yet been ascertained. Patterson, who wrote at the end of the
last century, mentions having seen mimosa forests densely inhabited by
these birds, who congregate in the hope of preserving their eggs from the
numerous snakes. For this purpose, hundreds of them build their nests
beneath one large roof, resembling a thatched house in its appearance.
This roof (see p. 168) is fixed to a large branch or portion of the tree,
and under it the actual nests are placed so closely together that it
would be quite impossible for a snake or any other enemy to penetrate to
the interior. All day long the busy crowd of workers hurry to and fro,
resembling a swarm of bees in their industry, and, like them, return
laden with everything needful for the construction or improvement of
their homes, while year by year the settlement increases in size, until
at last the tree literally bends beneath the weight of the superincumbent
colony. The entrances to the interior are very numerous, and situated
underneath the massive edifice, each opening leading to a kind of
corridor or street, on both sides of which are the small and very secure
apartments provided for the young. These birds subsist upon the seeds of
the grasses employed in the construction of their dwellings. The above
account has been verified by Mr. A. Smith, a well-known traveller and
naturalist, from whom we learn that each couple works at its own portion
of the building, all co-operating, however, in the common endeavour to
concentrate the nests under one substantial straw thatch, and thus ensure
the safety of the whole flock. These aerial cities are generally built
upon large branches at a considerable elevation, but the Tree Aloe is
occasionally selected as affording suitable support. The brood of the
Social Weaver Bird consists of three or four blueish-white eggs, marked
with small brown spots at their broadest end. The young are fed entirely
upon insects, which are only occasionally eaten by the parents.