The swans are among the most ornamental of all water-birds, on account
of their great size, the gracefulness of their forms and motions, and
the snowy whiteness of the plumage of the most familiar species. From
the remotest antiquity they have attracted attention, and the
time-honored fable of the tame swan acquiring a musical song when dying,
instead of the husky voice which usually characterizes him, is still
repeated, though wholly destitute of foundation. The notion probably
arose from confounding the wild species with the tame one, for though
the note of the wild swan, or Whistler, is certainly not musical, yet
there is a mournful sonorousness about it, which gives it not a little
of the expression of a death-song. It is a dull and solemn hwoo-hwoo,
having what is called an inward sound, though audible at a considerable
distance. From this note they have acquired a popular name, that of the
Hooper. They pass the period of reproduction in high northern latitudes,
and in the autumn migrate southwardly over both continents. In winter
they are sometimes quite numerous in the waters of the Chesapeake, and
flocks are seen passing through the interior along the valley of the
Mississippi to the lands around the mouth of that river. The Hooper
emits his note only when flying, or calling on his mate, and though loud
and shrill it is by no means unpleasant, particularly when heard high in
the air, and modulated by the winds. Its vocal organs are remarkably
assisted by the structure of the trachea, which forms two
circumvolutions within the chest, before terminating in the respiratory
organ. On their migratory flights they fly very high in the air, and
close to each other. The height of their flight is probably intended as
a security against their enemies, the falcons, who would prove more than
a match for the swans, notwithstanding their great size and strength, if
they were able to take “the sky” of them. The swan has little or no
means of defence when it is on the wing, the stroke of the wing being
what it chiefly depends on for its defence against an enemy, and this
being but little available when the bird is flying. By taking the sky of
the hostile birds, the swan, however, is enabled to perform its
migratory flight in considerable safety, as the falcons are entirely
harmless to any thing above them. The flight of the Hoopers when they
are on their migrating journeys is much more rapid than from the size
and weight of the birds one would be apt to suppose. As is the case with
all birds of lofty flight, it does not appear to be so rapid as it
really is. This is a point to which it is very essential to attend in
all cases of birds, or indeed any thing else in motion. The portion of
the retina which the visual impression of the observed object passes
over is of course the standard which we have for the measure of its
velocity. In consequence of this, its motion appears to be slower than
it really is, in the same proportion that its distance is increased, so
that a motion at five hundred yards requires to be ten times faster in
order to have the same apparent speed as a motion at fifty yards
distance. This renders it rather a difficult matter for an ordinary
sportsman, however expert he may be in hitting partridges or other
ground game when on the wing, to hit swans when they are passing over
him in their migratory flight; and unless he takes aim before them, at a
distance which experience only can determine, he is sure to miss. The
wind, too, must be taken into calculation in order to insure a
successful shot. The size and weight of the swans, with the abundance of
their feathers, cause the wind to have a very great influence on the
velocity of their flight. Hence they almost invariably go before the
wind in their migrations, and wait, or even halt on their journey, if
the wind be adverse. Before a stiff breeze they can make way at the rate
of not less than one hundred miles in the hour, so that they are very
soon out of the observer’s horizon; but against a wind of the same
strength they can make very little way, and upon a strong cross wind
they drift very far to leeward.
In all ages these birds have enjoyed a considerable degree of fictitious
interest, and, therefore, beside the exaggeration of the musical power
of their “sweet voices,” there are various other improbable things
alleged of them. For instance, it is said that when the frost begins to
set in they assemble in multitudes and keep the water in a state of
agitation to prevent it from freezing. The fact is, that all the
agitation a flock of swans could produce in a lake would but make it
freeze the more rapidly. It is probable, however, that they break the
ice, when it is thin, and continue breaking it at the same place as fast
as it freezes, as is the habit of very many animals in the winter
season.
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[Illustration: Drawn by Ch. Bodmer, Eng^{d} by Rawdon, Wright & Hatch
FORT MACKENZIE.]
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