SWIFTS AND NIGHT-JARS
“The swift is that large black swallow that flies in flocks on summer
evenings and utters a shrill cry as it passes. Hunting insects on the
wing is its occupation. It has a very short beak that opens wide, a big
gullet, always coated with a glue that holds the captured game, long
and pointed wings which enable it to cover in continuous flight eighty
leagues an hour, and piercing eyes capable of seeing a gnat at a
hundred meters’ distance, or even farther. Every insect that ventures
into the upper air is lost: the swift’s open beak is a living trap, a
trap that advances rapidly to swallow up the tiny prey.
“If the bird has little ones, it sometimes stows away its prey in its
cheek-pouches and, when they are full, returns to its nest to feed
these provisions to the hungry mouths waiting to be filled, discharging
through its beak the accumulated flies, moths, and beetles.
“What a slaughter of twilight-flying insects takes place when the
screaming flocks of swifts fly hither and thither, circling about in
the calm glow of sunset! What an onrush of whirring wings! What dash
and eagerness! How animated the scene! Some fly merely as chance
dictates, letting themselves glide gently through the air for the mere
pleasure of the motion; others describe intertwining circles without
number; others, again, soar aloft on motionless wings or let themselves
fall from dizzy heights as if wounded and helpless; still others follow
a straight course, racing toward some distant goal and then returning
for a fresh start; and, finally, there are those that go whirling in
noisy companies about some lofty building. But what of this one that
darts across our vision in such hot haste? It flashes past with three
strokes of the wings and is lost in the haze of the distance. What
impetuosity, children, what amazing speed!”
“I have often wished I could fly when I was watching those birds,” said
Emile. “If I only had their wings to carry me to those blue mountains
we see from here, how I should like to go flying to the top of that
highest peak and then come back as quickly as I went!”
“That wish, my boy, is common to us all; every one must envy the swift
its wings, but certainly no one would ever think of envying it its
feet.”
“Why?”
“Because they are so misshapen and the legs are so short that they
cannot be used for walking. All four toes point forward. That tells you
the swift does not perch, being unable to grasp the supporting branch,
but must cling to walls for a brief rest, after which it must take
flight again, starting with a falling movement as bats do. Guéneau de
Montbéliard tells us this:
“‘Swifts have to be on the wing a great part of the time. They never
voluntarily alight on the ground, and if by some accident they fall to
earth they cannot rise again into the air without extreme difficulty,
by dragging themselves up on to a little mound or by climbing with beak
and claws upon a stone from which they can spread their long wings. If
the ground is quite level they either lie prone on the stomach or sway
from side to side with a balancing motion, or they manage to struggle
forward a little by beating the earth with their wings. After repeated
efforts they sometimes succeed in flying off. The earth, therefore, is
to them a great danger that must be avoided with the utmost care. Any
state between swift motion and absolute rest is hardly possible with
them. Violent exercise in the air and perfect quiet in their place of
retreat—these two, as a rule, make up their existence. The only
variation known to them is to hang on to some wall near their hole and
then drag themselves into the nest by clambering along with the help of
beak and any chance support that they can find. Usually they enter
their retreat in full flight. After passing and repassing its entrance
more than a hundred times, all at once they dart in so quickly that
they are lost to sight before you know whither they are gone. You feel
almost inclined to believe they have vanished into thin air.’
“Their nest is nearly always placed in a deep hole in the wall and at a
great height. It is made of hemp threads, little wisps of tow, bits of
straw, feathers, rags, and cotton-like down from poplar and willow
catkins. These materials are stuck together with the viscous saliva
that constantly oozes from the swift’s throat and serves as glue to
entangle captured insects. The bird spreads it over the nest and
thoroughly moistens the successive layers. In drying this saliva
hardens and takes on the shiny appearance of gum, giving consistency
and even elasticity to the whole structure. If you squeeze the nest
between your two hands it will shrink up without breaking, and when the
pressure is removed it will resume its former shape.
“The swift, then, furnishes its own adhesive cement, but whence does it
obtain the other materials it needs, such as tow, rags, straw, and
feathers? Of course it is not so foolish as to go and pick them up from
the ground, where it might find them as other birds do; for if it
touched the ground it would certainly come to grief. Therefore it
resorts to cunning. As it reaches us rather late in the season, it
takes advantage of such holes as it finds already abandoned by the
sparrows, and there it finds abundant materials which it uses in its
own way by sticking them together with its glue. If the sparrows have
not yet broken up housekeeping, it boldly invades their nests, steals
bits of flock and tufts of hair, straw, and feathers, a little from one
and a little from another, and makes with these its own nest in another
hole in the same wall. The female lays from two to four eggs, pure
white and rather elongated. Swifts seldom stay more than three months
with us. Arriving after the swallows early in May, they leave at the
end of July.
“The white-breasted swift differs from the bird I have just described
in being larger and having a white breast and stomach. It is found in
the region of the Alps and of the Pyrenees and frequents the
Mediterranean shores, especially where the waves beat against high,
steep cliffs. Middle and northern Europe are not visited by this bird.
Its flight is even swifter than that of its black cousin, and it flies
habitually at a great height, descending only when bad weather
threatens. It builds its nest at the summit of high, steep rocks,
making it of straw and moss stuck together with the glue from its own
throat.
“The night-jar closely resembles the swift, having, like that bird, a
short beak which is very broad at the base and opens very wide, while
from the gullet comes a sticky saliva for holding fast any insects that
are caught. Its size is about that of the thrush; its plumage is light,
soft, and shaded with gray and brown; its eyes are large and prominent
and very sensitive to light; the base of its beak bristles with long,
stiff hairs; and its legs are short, but at the same time not ill
adapted to walking.
“As indicated by the sensitiveness of its eyes, which cannot endure the
full light of day, and by the softness and lightness and gray color of
its plumage, which resembles that of the hornless owl, the night-jar is
a twilight bird: it is the swift of the evening, flying and hunting
only when the sun is near setting. By the fading light of a summer
evening it may be seen scanning the ground in low flight to and fro
over its surface, after the manner of the swallow. It flies with mouth
wide open, so that the air in striking the throat produces a low and
continuous humming like that of a spinning-wheel.”
“And is it from that humming sound that it gets its name of night-jar?”
asked Jules.
“Precisely. But it does not make this humming sound for the mere love
of hearing it; its object is to snap up the twilight-flying insects as
it passes with distended beak. Big beetles sporting in the evening air,
June-bugs, and other plump winged creatures disappear in the viscous
gullet, while small butterflies, moths, gnats, and mosquitoes become
entangled by the dozen in the fatal glue. If the game is large, the
bird swallows it at once, whole and still alive; if small, it waits
until it has caught a certain number and then swallows them all in one
mouthful.”
“But does it really swallow big beetles and June-bugs alive?” Emile
asked.
“You can readily understand that in its headlong chase the bird has no
time to dismember its captives. Pouncing upon the insect with wide-open
beak, snapping it up, and gulping it down—all this it does as it flies,
without a moment’s pause. No sooner is the plumpest prey captured than
down it goes, alive and struggling, into the bird’s crop.”
“A dozen of that sort of game must stir up a big rumpus in the bird’s
crop,” was Emile’s opinion.
“Almost any other creature in the night-jar’s place would have its
digestion ruined by a brisk company of coleopters kicking about in the
stomach and tickling its walls with their rough and prickly legs; but I
am inclined to believe the bird has the means of quieting them
immediately by smothering them with its digestive juices. As it carries
on the business of stuffing its crop with large live beetles, it ought
to know the secret of how to prevent their making a hole in its
stomach. But that does not lessen my admiration for its digestive
powers. No creature enjoys a more remarkable immunity from dyspepsia.
“On a near view the night-jar is not a pretty bird. Its flat skull; its
tremendously yawning beak, which seems to split the whole head in two;
its wide-open gullet, red and slimy and powdered with the remains of
moths recently devoured; its large and prominent eyes—all these give it
somewhat the appearance of a toad. That is why it is sometimes called
the flying toad. Another common name for it is goat-sucker, based on a
false belief as to one of its habits. It likes to visit pastures and
sheepfolds, where it chases the beetles to be found there. Noting its
frequent appearance among the sheep and goats, shepherds imagined it
came there to suck their milk. If they had watched it more closely they
would have seen the absurdity of any such notion. A bird suck? What
nonsense! But the more ridiculous an idea is, the more likely it is to
spread, and the absurd name of goat-sucker is better known in many
places than the appropriate and expressive one of night-jar.
“This bird comes to us from warmer lands toward the beginning of May,
and leaves us in September. It builds no nest, imitating in this
various nocturnal birds of prey. Some hole in the ground or among
broken stones, at the foot of a tree or a rock, and usually taken just
as it happens to be, suffices to hold the bird’s eggs, which are two or
three in number, white with tawny and bluish spots.
“In closing let me beg you to remember what we owe these big-throated
birds that hunt insects on the wing, and more especially the swifts and
swallows, who defend our granaries and gardens, our wardrobes and our
very persons. What would you think of any one who, possessing the
terrible secret of creating by the bushel moths, gnats, mosquitoes,
weevils, and other destructive insects, should let loose a swarm of
these creatures in the air about us?”
“I should say hanging was too good for him,” answered Louis.
“But that is exactly what any one does who kills a swallow. It is true
he does not create moths and mosquitoes and other insects, but he saves
the lives of those that the swallow would have eaten, and thus he is
guilty of as grave an offense as if he had created them on purpose to
turn them loose on us. He does a wicked deed, for he receives with
deadly shotgun the pretty, joyous creature, messenger of spring and
sunshine, that comes trustfully asking his hospitality and the
permission to build its nest under the eaves of his house. He causes
famine, for he encourages the multiplication of those devouring hordes
that levy every year on our farm products a tax that amounts to
thousands of millions of francs in its total sum and is constantly
increasing as insect-eating birds decrease. A wicked deed, I say, a
deed which causes famine—that is what is really done by the murderer of
swallows.”