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Every now and then in our press appear blasts against crowded living
conditions in our cities, and the tenements where people are crowded
together. Often there is the implication that this type of thing is
unnatural and abnormal. And yet when we look about us in the bird world
we see that gregariousness is a common trait. We have only to remember
the great flocks of starlings and blackbirds in the autumn, or the
massed flights of water fowl. Not only in traveling and in feeding, but
also at nesting time birds may gather together, and some birds nest in
such close association that the term "apartment houses" or "tenement"
is really applicable.
The martins' house on our lawn with perhaps dozens of closely spaced
rooms (some houses have as many as two hundred rooms) is a case in
point. The neat martin house, made of boards, is a man-made thing,
but even before the white man came to this continent, and before the
Choctaw Indians hung up groups of hollow gourds for the martin colonies
to use, the martins nested in colonies. Even in recent years certain
colonies we might consider unprogressive have been reported as using
such diverse nesting situations as among the boulders of a lake shore
in Minnesota, and the closely spaced woodpecker holes which riddled
a dead pine in Florida. And probably it was always thus. The martins
liked company at nesting.
CLIFF DWELLERS, TOO Perhaps it would not be proper to consider a colony
of bank swallows, each with a separate burrow in the same small cut
bank and roofed with the same few square yards of turf of mother earth,
as a real apartment house of cliff dwellers. But the term has been used
in connection with a West Indian woodpecker, where a dozen pairs were
nesting in a single dead tree, and "the trunk was a veritable apartment
house." A similar situation exists with the naked-faced barbet of West
Africa. This bird too makes a hole in a dead tree for its nest, like a
woodpecker, and colonies of thirty to fifty birds may be found nesting
in a single dead tree, while other dead trees nearby, apparently
equally suitable, are untenanted. Colonies of hundreds of nests of
cliff swallows, the nests touching and overlapping, may be under the
eaves of a single barn, or as they used to be and some still are, on
the sheltered side of a cliff. But as these birds had nothing to do
with the making of the roof, perhaps these too do not deserve to be
rated as apartment houses.
In southern South America there is a monk parakeet that makes a real
tenement. It nests colonially in treetops, and the nests of sticks are
placed so close together that they merge and form a single mass, up to
nine feet across, in which each parakeet has its own nest. Similar to
this is the palm chat. This West Indian bird is small and thrush-sized,
dull in color, brownish with a streaked breast, nothing remarkable to
look at, but it carries amazingly large sticks, little thinner than a
lead pencil and as much as two feet and more long up to the top of a
palm tree, and there it makes its bulky community nest.
BUILD NESTS CO-OPERATIVELY These stick nests, which may be four feet
and more across, are conspicuous and regular features of the landscape
in Hispaniola. The colony consists of four to eight pairs of birds,
and each has its own apartment in the bulky structure, and its own
passageway to the outside. But in the parts of the community nests that
hold the individual nests together and cover them there are roughly
defined passages running through the interlacing twigs of the top of
the nest so that the birds can creep about under cover. Apparently some
of the work is carried on in common, for as many as half a dozen birds
may be working close together, pulling and twisting twigs more firmly
into place.
The social weaver is the most advanced apartment builder. It, like the
palm chat, has little of distinction in its appearance, being mostly
dull brownish with a black face. But in its home country, the savannas
of Rhodesia in southeastern Africa, its huge community nests in the
savanna trees may be seen from afar. The largest Friedmann saw when he
was studying the bird there was about 25 feet by 15 feet, by 5 feet
high, and contained about 95 nests. And this might have been still
bigger, for part of it had broken the branch on which it rested and
fallen to the ground. Sir Andrew Smith, the early ornithologist of
South Africa, has written that when these birds start a colony they
first of all make a roof of coarse grass. The group to which the social
weaver belongs gets its name from the remarkable ability some of them
have of weaving their nesting materials. But the social weaver neither
plaits nor weaves its roof. It puts the roof together in the form of a
well-made hayrick with a fairly definite thatching arrangement so that
the water runs off. This is a community effort. Under this roof each
individual pair makes its own separate nest. These apartment houses are
used year after year, but last year's chambers are not used, new ones
being made under the roof each year, and so it grows bigger and bigger
until the weight of the mass may break the branches and cause a part or
the whole to fall to the ground.