THE PALMIPEDES
“The workman is known by his tools, and by the tools of the feathered
creatures—that is to say, their beaks and claws—their way of life is
not less easily recognized. If it were not already known to us, who
could fail to infer the carnivorous disposition of the hawk from the
shape of its beak—short, sharp, and hooked—and from the structure of
its talons, armed as they are with pointed nails grooved underneath
with a narrow channel after the manner of certain daggers, to
facilitate the flow of blood from the wound? Does it call for any
extraordinary perspicacity to recognize, in the heron’s long legs,
veritable stilts which enable it to traverse, step by step, without
getting wet, the inundated flats, as does the hunter in his long,
waterproof marsh boots? And then, that long beak, pointed like a nail,
does it tell us nothing? Does it not say that the bird bores deep in
the tufts of rushes and in the soft mud to pull out reptiles and
worms?”
“It is the heron,” put in Emile, “that the fable tells about when it
says:
“The long-necked, long-beaked heron went walking;
On its stilt-like legs one day it went stalking.”
“Yes,” said Uncle Paul, “that is the bird. Everything about the heron
is long—legs, beak, neck. The length of its legs enables the bird to
explore the swamp at its ease all day long without wetting a feather;
its length of neck is needed that it may reach the ground without
stooping; and the long beak is indispensable for burrowing in the tall
tufts of grass where the reptile lurks, and for probing the mud where
the worm buries itself.”
“I begin to see now,” said Jules, “how the character of a bird may be
judged from its shape. The heron bears its trade stamped on its form.”
“The duck, in its turn, makes an equally unmistakable announcement. Let
us forget its habits, which are so familiar to us, and try to
rediscover them in the shape of the legs and beak.
“The duck’s beak is very wide and flat, and round at the end. Shall we
compare it with the hen’s beak, a slender pair of pincers that snaps up
seeds and kernels one by one? Comparison is impossible. Do we see there
a tool working in the manner of the heron’s pointed probe? Still less.
Shall we make it the equivalent of the bloody hooked beak of the bird
of prey? No one would dream of such a thing, so great is the
difference. But one sees at once in this wide, rounded beak a spoon
shaped expressly for scooping up food from the water, just as our
table-spoons enable us to take out pieces of bread or lumps of rice
swimming in a thin soup. The duck dabbles, then: it dips up water in
large spoonfuls—that is to say, in beakfuls—and seeks its food therein.
It is a soup of the thinnest sort and, in itself, of no nutritive
value. Consequently the liquid that fills the bird’s mandible must be
rejected, but at the same time it must be drained out in such a manner
as to leave behind what little alimentary matter it may contain. For
this purpose the edges of the beak are fringed with a row of thin,
short blades which let the liquid run out when the bird has once filled
its mouth.”
“That’s an ingenious way to eat,” remarked Jules. “In order to snap up
what it takes a fancy to, perhaps a tadpole, or a little water shell,
or a worm, the duck is obliged to fill its beak with water. To swallow
the whole mouthful without sorting would simply stuff the crop with a
useless liquid. What does the bird do? It closes the beak, and the
water, driven back, runs out through the fringed edges as if through a
grating. The tadpole alone remains behind the grating, and goes down
into the stomach.”
“You can see, any time,” observed Louis, “the ducks on the pond dipping
up water by the mouthful. It certainly isn’t just for drinking that
they work their beaks so.”
“Certainly not,” assented Uncle Paul; “they drain the water of the pond
through the fringe of the beak to gather worms and other small aquatic
prey.
“The spoon-shaped beak of the duck indicates the bird’s dabbling
habits; now let us see what the feet have to say. They are composed of
three toes connected by an ample and supple membrane. Is that, I ask
you, the footgear of a bird destined to long walks? With such a sole,
so fine, so tender, and by its extent of surface exposing itself so
much to the hardness of the stones, is the duck made for foot-racing?
Note, on the contrary, the foot of the hen and the guinea-fowl, both
untiring walkers. The toes are short, knotty, and sheathed with strong
leather, without any connecting membrane. That is the true footgear of
the pedestrian. But what will become of the duck on rough ground, with
its wide sandals that a mere nothing can wound? You all know its
pitiful walk. It waddles along, as ill at ease as a person afflicted
with corns on the rough pavement of some of our streets. No, the duck
is not made for walking.
“But in water those expanded feet will make vigorous swimming oars. If
the bird throws them out behind, they spread wide open merely with the
resistance of the water; and their fan-shape gives them purchase enough
to send the duck forward. When the duck draws them in again under its
breast, they are closed automatically by the resistance of the liquid
acting in a contrary direction; the membrane refolds in the manner of a
closed umbrella, thus doing away with all shock or recoil. The twofold
essential of a perfect oar lies in its presenting to the water the
greatest possible surface on the stroke, and the least possible surface
on the recovery, so as to furnish adequate purchase against the water
in the first movement and to offer only very feeble resistance in the
second. If the oar moved alternately forward and backward while
presenting the same extent of surface to the water and driven with the
same vigor, the recoil would equal the advance and there would be no
progress. Man, with all his skill, does not yet know how to ply his oar
so that it shall offer this alternating maximum and minimum of surface.
Therefore, in propelling a boat, he is obliged to bring the oars back
to their first position through the air instead of through the water,
which latter would be much more direct. The duck scorns this clumsy
method: with its foot, which opens wide of itself in the backward
thrust and closes again of its own accord in the return movement, it
moves forward or puts about, without ever lifting the oars from the
water.
“Thus the duck is an expert swimmer; the shape of its feet tells us as
much, and a glance at any duck-pond demonstrates it. Who has not
admired the aquatic evolutions of the bird, so awkward on land with its
tender feet, so graceful when once on the water, its proper element?
Sometimes they race with one another, whitening their breasts with a
band of foam; sometimes, in order to explore the depths with their
beaks, they plunge half-way in and point their tails heavenward;
sometimes, also, yielding to the current, they let themselves drift
idly down-stream or hold their position by paddling a few strokes when
necessary. Water is their chosen domain; there they take their
recreation, seek their food, and enjoy their sleep.
“The membrane connecting the duck’s toes is called a web, and the feet
converted into oars by means of this membrane are spoken of as webbed.
Similar feet are found in all good swimming birds such as the swan,
teal, goose, and many others. Hence this group of birds, especially
skilled in swimming, is designated by the term of palmipede, meaning
web-footed.”
“Then the duck is a palmipede?” asked Emile.
“It is a palmipede, as also the goose, swan, and teal. All four are
equally endowed with a large spoon-bill shaped for dabbling in the
water; that is to say, a wide, round beak; but there are palmipedes,
notably among sea-birds, that live on prey, on fish, and consequently
are equipped with the crooked mandible appropriate for a predatory
life. Such, to take but a single example, is the albatross, of which I
here show you the picture. By its ferociously hooked beak it can easily
be recognized as a sea pirate, an insatiable devourer of fish.”
“I certainly don’t like its looks,” declared Emile. “But tell me now
what name they give the heron on its tall stilts.”
“The heron belongs to the group of stilt-birds or wading-birds. That is
what they call all birds mounted on long legs for traversing the
marshes.”
“A bird on stilts is a stilt-bird; it would be hard to improve on that.
It is just the kind of name I like.”
“Instead of allowing ourselves to be turned from our theme by the heron
and its stilts, let us come back, my little friend, to the palmipedes,
the swimming birds. Clothing made expressly for the purpose is required
by the bird that passes the greater part of its time on the water. It
is indispensable that this clothing should keep out both cold and wet.
Well, the plumage of an aquatic bird, especially in very cold
countries, is a marvel of delicate precautions. The outside feathers
are strong, placed very accurately one on the other and glossed with an
oily varnish that water cannot wet. Have you ever noticed ducks as they
come out of the water? They may have prolonged their bath for hours,
swimming, diving, playing; but they leave the stream without getting
the least bit wet. If a drop of water has got between their feathers,
they have only to shake themselves a moment, and they are perfectly
dry. That, you must agree, is a precious privilege, to be able to go
into the water and not get wet.”
“A privilege that, for my part,” rejoined Emile, “I have often envied
without being able to explain—the secret of a duck’s keeping dry when
right in the water.”
“I will explain the secret to you. Watch the ducks as they come out of
their bath. In the sun, some lying at ease on their stomachs, others
standing up, they proceed to make their toilet with minute care. With
their large beak they smooth their feathers, one by one, coat them over
with an oily fluid, the reservoir of which is situated on the bird’s
rump. There, just at the base of the tail, is found, hidden under the
down, a kind of wart of grease, from which oil oozes constantly. From
time to time the beak presses the wart, draws from the oily reservoir,
and then distributes here and there, methodically, all over the
plumage, the oil thus obtained.”
“That greasy wart might be called a sort of pomatum pot,” suggested
Emile.
“It is a pomatum pot, if that comparison pleases you. Thus greased,
thus anointed with pomatum, feather by feather, the duck furnishes no
foothold for moisture, because, as you all know, water and oil do not
mix, and from an oiled surface drops of water run off without wetting
it. Such is the secret of the duck’s keeping itself dry when immersed
in water.”
“That is one of the most curious things I ever heard of,” declared
Jules, “and one that I shouldn’t have known anything about for a long
time if it hadn’t been for Uncle Paul. Should I ever have guessed that
the duck presses a certain wart on its rump to get the grease for
oiling its feathers?”
“The duck’s secret is known to all birds without exception; all have
this oil-sac on the rump, and obtain from it the oil for giving luster
to their plumage and making it impervious to wet; but aquatic birds are
more abundantly provided in this respect. And it is only right that
those most exposed to dampness should have the largest reservoir of
this oily coating.”
“In all birds the fattest part is always the rump,” said Louis. “Grease
gathers there by preference, no doubt, to maintain the store of oil in
the oil-sac?”
“Evidently. It is in this storehouse that the oil attains its perfect
state and becomes the finished product that oozes from the sac. As to
the making of it in the first place, nearly all parts of the body take
part; and as the swimming bird uses a great deal of this pomatum, the
result is that the palmipede tends to fatness and, as it were, sweats
grease: witness the plump duck and goose, which carry under the breast
a heavy, fat swelling. As a general rule, the web-footed fowl of our
poultry-yards is analogous to the pig: it is a fat-factory. We divert
to our own use the excess of fat accumulated primarily for the supply
of the oil-sac on the rump and the maintenance of the luster that
distinguishes the plumage.
“The palmipede, you see, is admirably protected against wet. Neither
rain nor the finest drizzle can penetrate the first covering of
feathers, always kept, as it is, well coated with the varnish laid on
by the point of the beak. The bird can plunge into the deepest water,
swim on its surface, or sleep there cradled by the waves, and the wet
will not reach it. Neither will cold affect it, for under this outer
covering is found a second, designed for resisting inclement weather
and made of what is most efficacious for preserving the heat of the
body. This under-clothing of aquatic birds is a down so delicate and
soft that, unable to compare it with anything else, we have given it a
special name, that of eiderdown. In its proper place I will come back
to this down. For the present let us confine ourselves to a general
survey of the palmipedes, and of the duck in particular.”