(WHITE-RUMPED SWALLOW.)
+Hirundo leucorrhoa+, _Hudson, P. Z. S._ 1872, pp. 606, 845 (Buenos
Ayres); _Scl. et Salv. Nomencl._ p. 14; _Durnford, Ibis_, 1877,
p. 32 (Chupat), 1878, p. 392 (Central Patagonia); _White, P. Z.
S._ 1882, p. 596 (Corrientes); _Barrows, Bull. Nutt. Orn. Cl._
viii. p. 89 (Concepcion). +Cotyle leucorrhoea+, _Burm. La-Plata
Reise_, ii. p. 478 (Paraná). +Tachycineta leucorrhous+, _Sharpe,
Cat. B._ x. p. 114.
_Description._--Above glossy dark green; rump white; quills black,
washed with green; upper tail-coverts dark green; tail-feathers
black with greenish gloss; base of forehead white, extending a
little backward over the lores; cheeks and whole under surface
white; flanks and sides washed with smoky brown; axillaries and
under tail-coverts pale smoky brown; bill and feet black: total
length 5·5 inches, wing 4·45, tail 2·0. _Female_ similar.
_Hab._ Brazil, Paraguay, and Argentina.
This is the most abundant and best known of our Swallows; a pretty bird
in its glossy coat of deep green, and rump and under surface snowy
white; exceedingly restless in its disposition, quick and graceful in
its motions; social, quarrelsome, garrulous, with a not unmusical song,
beginning with long, soft, tremulous notes, followed by others shorter
and more hurried, and sinking to a murmur. They are the last of all our
migrants to leave us in autumn, and invariably reappear in small numbers
about the houses on every warm day in winter. Probably many individuals
in Buenos Ayres remain through the winter in sheltered situations, to
scatter over the surrounding country whenever there comes a warm bright
day. I once saw three together, skimming over the plains, on one of the
coldest days I ever experienced on the pampas, the thermometer having
stood at 29° Fahr. that morning.
Further south their migration is more strict; and on the Rio Negro, in
Patagonia, from March to August I did not meet with a single individual.
In Buenos Ayres the autumnal migration of the Hirundines begins about
the middle of February, and from that date vast numbers of this Swallow
are seen travelling north, and, in some seasons, they continue passing
for over a month. One autumn, in April, several days after the Swallows
had all disappeared, flocks of the Common Swallow began again to appear
flying north, and for ten days afterwards they continued to pass in
large numbers. They would stoop to dip themselves in a pool where I
observed them, and then alight on the reeds and bushes to rest, and
appeared quite tired with their journey, rising reluctantly when
approached, and some allowing me to stand almost within arm's length
of them without stirring. I had never before observed any later or
supplementary migration like this; for, as a rule, the causes which in
some years delay the departure of birds seems to affect them all alike.
Possibly these late birds come from some remote district, where
exceptionally cold weather had retarded breeding-operations.
The White-rumped Swallow sometimes lays in a tree, in the large nest,
previously abandoned, of the Leñatero (_Anumbius acuticaudatus_).
Its favourite site is, however, a hole in a wall, sheltered by the
overhanging tiles or thatch; for though it does not go much into towns,
as Azara has remarked, it is very domestic, and there is not a house on
the pampas, however humble it be, but some of these birds are about it,
sportively skimming above the roof, or curiously peering under the
eaves, and incessantly uttering their gurgling happy notes.
For a period of a month to six weeks before building begins they seem to
be holding an incessant dispute, reminding one in their scolding tones
of a colony of contentious English House-Sparrows, only the Swallow
has a softer, more varied voice, and frequently, even when hotly
quarrelling, he pauses to warble out his pretty little song, with its
sound like running water. However many eligible chinks and holes there
may be, the contention is always just as great amongst them, and is
doubtless referable to opposing claims to the best places. The excited
twittering, the incessant striving of two birds to alight on the same
square inch of wall, the perpetual chases they lead each other round
and round the house, always ending exactly where they began, tell of
clashing interests and of great unreasonableness on the part of some
amongst them. By-and-by the quarrel assumes a more serious aspect;
friends and neighbours have apparently intervened in vain; all the
arguments of which Swallows are capable have been exhausted, and, a
compromise of claims being more impossible than ever, fighting begins.
Most vindictively do the little things clutch each other and fall to the
earth twenty times an hour, where they often remain struggling for a
long time, heedless of the screams of alarm their fellows set up above
them; for often, while they thus lie on the ground punishing each other,
they fall an easy prey to some wily pussy who has made herself
acquainted with their habits.
When these feuds are finally settled, they address themselves diligently
to the great work and build a rather big nest. They are not neat or
skilful workers, but merely stuff a great quantity of straw and other
light materials into the breeding-hole, and line the nest with feathers
and horsehair. On this soft but disorderly bed the female lays from five
to seven pure white eggs.
All those species that are liable at any time to become the victims of
raptorial birds are very much beholden to this Swallow, as he is the
most vigilant sentinel they possess. When the hurrying Falcon is still
far off, and the other birds unsuspicious of his approach, the Swallows
suddenly rush up into the sky with a wild rapid flight to announce the
evil tidings with distracted screams. The alarm spreads swift as light
through the feathered tribes, which, on all sides, are in terrified
commotion, crouching in the grass, plunging into thickets, or mounting
upwards to escape by flight. I have often wondered at this, since this
swift-winged and quick-doubling little bird is the least likely to fall
a prey himself.
They possess another habit very grateful to the mind of every early
riser. At the first indication of dawn, and before any other wild bird
has broken the profound silence of night, multitudes of this Swallow, as
if at the signal of a leader, begin their singing and twittering, at the
same time mounting upwards into the quiet dusky sky. Their notes at this
hour differ from the hurried twittering uttered during the day, being
softer and more prolonged, and, sounding far up in the sky from so many
throats, the concert has a very charming effect, and seems in harmony
with the shadowy morning twilight.