(BANK-SWALLOW.)
+Atticora cyanoleuca+, _Burm. La-Plata Reise_, ii. p. 479; _Scl. et
Salv. Nomencl._ p. 14; _Hudson, P. Z. S._ 1872, p. 844 (Buenos
Ayres); _Durnford, Ibis_, 1876, p. 158 (Buenos Ayres), 1877,
p. 32 (Chupat), p. 170 (Buenos Ayres), 1878, p. 392 (Central
Patagonia); _White, P. Z. S._ 1882, p. 596 (Catamarca); _Barrows,
Bull. Nutt. Orn. Cl._ viii. p. 90 (Concepcion, Bahia Blanca);
_Sharpe, Cat. B._ x. p. 186.
_Description._--Above dark glossy blue; quills and tail-feathers
black; cheeks and under surface of body pure white, the sides of the
neck blue, descending in a half-crescent on the sides of the chest;
sides of body and flanks brown; under tail-coverts black; bill and
feet black: total length 4·7 inches, wing 4·05, tail 2·2. _Female_
similar.
_Hab._ Central and South America.
This diminutive dark-plumaged species is the smallest of our Hirundines.
In Buenos Ayres they appear early in September, arriving before the
Martins, but preceded by the Common Swallow. They are bank-birds,
breeding in forsaken holes and burrows, for they never bore into
the earth themselves, and are consequently not much seen about the
habitations of man. They sometimes find their breeding-holes in the
banks of streams, or, in cultivated districts, in the sides of ditches,
and even down in wells. But if in such sites alone fit receptacles for
their eggs were met with, the species, instead of one of the commonest,
would be rare indeed with us; for on the level pampas most of the
water-courses have marshy borders, or at most but low and gently
sloping banks. But the burrowing habits of two other animals--the
Vizcacha (_Lagostomus trichodactylus_), the common large rodent
of the pampas, and the curious little bird called Minera (_Geositta
cunicularia_)--have everywhere afforded the Swallows abundance of
breeding-places on the plains, even where there are no streams or other
irregularities in the smooth surface of the earth.
The Minera bores its hole in the sides of the Vizcacha's great burrow,
and in this burrow within a burrow the Swallow lays its eggs and rears
its young, and is the guest of the Vizcacha, and as much dependent on it
as the House-Wren and the Domestic Swallow on man; so that in spring,
when this species returns to the plains, it is in the villages of the
Vizcachas that we see them. There they live and spend the day, sporting
about the burrows, just as the Common Swallow does about our houses; and
to a stranger on the pampas one of these villages, with its incongruous
bird and mammalian inhabitants, must seem a very curious sight in the
evening. Before sunset the old male Vizcachas come forth to sit gravely
at the mouths of their great burrows. One or two couples of Mineras,
their little brown bird-tenants, are always seen running about on the
bare ground round the holes, resting at intervals with their tails
slowly moving up and down, and occasionally trilling-out their shrill
laughter-like cry. Often a pair of Burrowing-Owls also live in the
village, occupying one of the lesser disused burrows; and round them all
flit half a dozen little Swallows, like twilight-moths with long black
wings. It is never quite a happy family, however, for the Owls always
hiss and snap at a Vizcacha if he comes too near; while the little
Swallows never become reconciled to the Owls, but perpetually flutter
about them, protesting against their presence with long complaining
notes.
The nest, made of dry grass lined with feathers, is placed at the
extremity of the long, straight, cylindrical burrow, and contains
five or six white pointed eggs. I have never seen these Swallows
fighting with the Minera to obtain possession of the burrows, for
this industrious little bird makes itself a fresh one every spring,
so that there are always houses enough for the Swallows. After the
young have flown, they sit huddled together on a weed or thistle-top,
and the parents continue to feed them for many days.
As in size and brightness of plumage, so in language is the Bank-Swallow
inferior to other species, its only song being a single, weak, trilling
note, much prolonged, which the bird repeats with great frequency when
on the wing. Its voice has ever a mournful, monotonous sound, and even
when it is greatly excited and alarmed, as at the approach of a fox or
hawk, its notes are neither loud nor shrill. When flying they glide
along close to the earth, and frequently alight on the ground to rest,
which is contrary to the custom of other Swallows. Like other species
of this family, they possess the habit of gliding to and fro before a
traveller's horse, to catch the small twilight-moths driven up from the
grass. A person riding on the pampas usually has a number of Swallows
flying round him, and I have often thought that more than a hundred were
before my horse at one time; but, from the rapidity of their motions, it
is impossible to count them. I have frequently noticed individuals of
the four most common species following me together; but after sunset,
and when the other species have long forsaken the open grassy plain for
the shelter of trees and houses, the diminutive Bank-Swallow continues
to keep the traveller company. At such a time, as they glide about in
the dusk of evening, conversing together in low tremulous tones, they
have a peculiarly sorrowful appearance, seeming like homeless little
wanderers over the great level plains.
When the season of migration approaches they begin to congregate in
parties not very large, though sometimes as many as one or two hundred
individuals are seen together; these companies spend much of their time
perched close together on weeds, low trees, fences, or other slightly
elevated situations, and pay little heed to a person approaching, but
seem preoccupied or preyed upon by some trouble that has no visible
cause.
The time immediately preceding the departure of the Swallows is indeed
a season of very deep interest to the observer of nature. The birds in
many cases seem to forget the attachment of the sexes and their songs
and aerial recreations; they already begin to feel the premonitions of
that marvellous instinct that urges them hence: not yet an irresistible
impulse, it is a vague sense of disquiet; but its influence is manifest
in their language and gestures, their wild manner of flight, and their
listless intervals.
The little Bank-Swallow disappears immediately after the Martins. Many
stragglers continue to be seen after the departure of the main body; but
before the middle of March not one remains, the migration of this
species being very regular.