THE DEFENCE AND SANITATION OF DWELLINGS.
GENERAL PRECAUTIONS AGAINST POSSIBLE DANGER--SEPARATION OF
FEMALES WHILE BROODING--HYGIENIC MEASURES OF BEES--PRUDENCE OF
BEES--FORTIFICATIONS OF BEES--PRECAUTIONS AGAINST
INQUISITIVENESS--LIGHTING UP THE NESTS.
The building of comfortable dwellings is not the last stage reached by
the industry of animals. There are among them some who show genuine
skill in rendering them healthy and defending them against invasions
from without.
_General precautions against possible danger._--Some animals show,
even during the construction of the nest, extreme prudence in
preventing its site from being discovered. Several authors refer to
the stratagem of the Magpie, who begins several nests at the same
time; but only one is intended to receive the brood, and that only is
completed. The aim of the others is merely to distract attention. It
is around these latter that the bird shows ostentatious activity,
while it works at the real nest only for a few hours during the day,
in the morning and evening.
The Crane takes equally ingenious precautions in order that its
constant presence at the same spot may not arouse suspicion. It never
comes or goes flying, but always on foot, concealing itself along
tufts of reeds. De Homeyer even reports that the female at the time of
laying covers her wings and back with mud. When dried this gives the
animal a red tone, which causes it to be confused with neighbouring
objects; this is intentional mimicry.
The Linnet (Fig. 41) again, wrongly accused of wanting judgment, is
well aware that a pile of excrement at the foot of a tree announces a
nest in the branches. It is careful to suppress this revealing sign,
and every day takes it away in its beak to disperse it afar.
[Illustration: FIG. 41.]
Birds will sometimes take the trouble to remove the eggs or the nest
altogether, when the latter has been discovered, in order to avoid
further risks of danger. The American Sparrow Hawk has been observed
to do this, and the following incident is quoted by Bendire, from
MacFarlane's _Manuscript Notes on Birds Nesting in British America_,
concerning the Pigeon Hawk (_Falco columbarius_):--"On May 25, 1864, a
trusty Indian in my employ found a nest placed in a thick branch of a
pine tree at a height of about six feet from the ground. It was rather
loosely constructed of a few dry sticks and a small quantity of coarse
hay; it then contained two eggs; both parents were seen, fired at, and
missed. On the 31st he revisited the nest, which still held but two
eggs, and again missed the birds. Several days later he made another
visit thereto, and, to his surprise, the eggs and parents had
disappeared. His first impression was that some other person had taken
them; but after looking carefully around he perceived both birds at a
short distance, and this led him to institute a search which soon
resulted in finding that the eggs must have been removed by the parent
birds to the face of a muddy bank at least forty yards distant from
the original nest. A few decayed leaves had been placed under them,
but nothing else in the way of lining. A third egg had been added in
the interim. There can hardly be any doubt of the truth of the
foregoing facts."[110]
[110] Bendire, _Life Histories of North American Birds_,
1892, p. 301.
_Separation of females while brooding._--The Hornbill of Malacca[111]
assures the protection of its nest and of the female while she is
brooding in a singular manner. She lays in the hollow of a tree; as
soon as she begins to sit on her eggs, the male closes the opening
with diluted clay, only leaving a hole through which the captive can
pass her beak to receive the fruits which he brings her in abundance.
If the lady is thus cloistered as closely as in the most jealous
harem, her lord and master at least expends on her the most attentive
cares.
[111] Bernstein, "Ueber Nester und Eier einiger Javaschen
Voegel," _Cabani's Journ. f. Ornith._, 1859.
What can be the object of this strange custom? It has been asserted
that during incubation the female loses her feathers and becomes
unable to fly. The male would thus only wall her up as a precaution
for fear of seeing her fall from the nest; because if this deplorable
accident happened she would not be able to get back again. It seems to
me that the effect is here taken for the cause, and that the falling
off of feathers and torpidity must be the result rather than the
motive of cloistration. One is tempted to believe that the male
desires by this method to guarantee his female and her offspring
against the attacks of squirrels or rapacious birds.
_Hygienic measures of Bees._--Among the animals who expend industry on
hygiene and the protection of their dwellings, we must place Bees in
the first line. It may happen that mice, snakes, and moths may find
their way into a hive. Assaulted by the swarm, and riddled with
stings, they die without being able to escape. These great corpses
cannot be dragged out by the Hymenoptera, and their putrefaction
threatens to cause disease. To remedy this scourge the insects
immediately cover them with _propolis_--that is to say, the paste
which they manufacture from the resin of poplars, birches, and pines.
The corpse thus sheltered from contact with the air does not putrefy.
In other respects Bees are very careful about the cleanliness of their
dwellings; they remove with care and throw outside dust, mud, and
sawdust which may be found there. Bees are careful also not to defile
their hives with excrement, as Kirby noted; they go aside to expel
their excretions, and in winter, when prevented by extreme cold or the
closing of the hive from going out for this purpose, their bodies
become so swollen from retention of faeces that when at last able to go
out they fall to the ground and perish. Buechner records the
observations of a friend of his during a season in which a severe
epidemic of dysentery had broken out among the bees, which interfered
with the usual habits of the insects; on careful examination of a hive
it was found that a cavity in the posterior wall of the hive,
containing crumbled clay, had been used as an earth closet. Many
mammals are equally careful in this respect; thus, for example, the
Beaver, as Hearne observed, always enters the water, or goes out on
the ice, to urinate or defaecate; the faeces float and are soon
disintegrated.
Animals are also careful about aeration. Thus, among Bees, in a hive
full of very active insects the heat rises considerably and the air is
vitiated. A service for aeration is organised. Bees ranged in files
one above the other in the interior agitate their wings with a
feverish movement; this movement causes a current of air which can be
felt by holding the hand before the opening of the hive. When the
workers of the corps are fatigued, comrades who have been resting come
to take their place. These acts are not the result of a stupid
instinct which the Hymenoptera obey without understanding. If we place
a swarm, as Huber did, in a roomy position where there is plenty of
air, they do not devote themselves to an aimless exercise. This only
takes place in the narrow dwellings which Man grants to his winged
guests.
The attention of Ants to public hygiene is more than equalled by their
attention to personal hygiene. Without going into the question of
their athletic exercises, which have attracted considerable attention,
it is sufficient to quote one observer as to their habits of
cleanliness. McCook remarks:--"The Agricultural Ants--and the remark
applies to all other Ants of which I have knowledge--is one of the
neatest of creatures in her personal habits. I think I have never seen
one of my imprisoned harvesters, either _Barbatus_ or _Crudelis_, in
an untidy condition. They issue from their burrows, after the most
active digging, even when the earth is damp, without being perceptibly
soiled. Such minute particles of dust as cling to the body are
carefully removed. Indeed, the whole body is frequently and thoroughly
cleansed, a duty which is habitually, I might almost venture to say
invariably, attended to after eating and after sleep. In this process
the Ants assist one another; and it is an exceedingly interesting
sight which is presented to the observer when this general 'washing
up' is in progress."[112]
[112] H. C. McCook, _Agricultural Ants of Texas_, 1879,
chapter on "Toilet, Sleeping, and Funeral Habits," p. 125.
_Prudence of Bees._--Certain species exhibit very great prudence,
especially the _Melipona geniculata_, which lives in a wild state in
South America. They place their combs in the hollow of a tree or the
cleft of a rock; they fill up all the crevices and only leave a round
hole for entry. And even this they are accustomed to close every
evening by a small partition, which they remove in the morning. This
door is shut with various materials, such as resin or even clay, which
the bees bring on their legs as those of our own country bring pollen.
All these facts were observed with great exactness in a swarm given in
1874 by M. Drory (who during a long period of years studied every
Brazilian species of _Melipona_ at Bordeaux) to the Jardin
d'Acclimatation. It was even seen that the door might be put up under
certain circumstances in open day, as for example, when a storm or
sudden cold delays the appearance of the workers. If one of them
happened to be late it had to perforate the partition, and the hole
was then stopped up again.
[Illustration: FIG. 42.]
_Fortifications of Bees._--As these facts take place always they may
be called instinctive; but that is not the case with regard to
defences elevated with a view to a particular circumstance, and which
disappear when the danger to which they correspond disappears. Such
are the labours of the bees to repel the invasions of the large
nocturnal Death's-head Moth. (Fig. 42.) He is very greedy of honey,
and furtively introduces himself into the hives. Protected by the long
and fluffy hairs which cover him, he has little to fear from stings,
and gorges himself with the greatest freedom on the stores of the
swarm. Huber, in his admirable investigations,[113] narrates that one
year in Switzerland numbers of hives were emptied, and contained no
more honey in summer than in the spring. During that year Death's-head
Moths were very numerous. The illustrious naturalist soon became
certain that this moth was guilty of the thefts in question. While he
was reflecting as to what should be done, the bees, who were more
directly interested, had invented several different methods of
procedure. Some closed the entrance with wax, leaving only a narrow
opening through which the great robber could not penetrate. Others
built up before the opening a series of parallel walls, leaving
between them a zigzag corridor through which the Hymenoptera
themselves were able to enter. But the intruder was much too long to
perform this exercise successfully. Man utilises defences of this
kind; it is thus at the entrance of a field, for example, he places a
turnstile, or parallel bars that do not face each other; the passage
is not closed for him, but a cow is too long to overcome the obstacle.
In years when the Death's-head Moth is rare the bees do not set up
these barricades, which, indeed, they themselves find troublesome. For
two or three consecutive years they leave their doors wide open. Then
another invasion occurs, and they immediately close the openings. It
cannot be denied that in these cases their acts agree with
circumstances that are not habitual.[114]
[113] Huber, _Nouvelles observations sur les Abeilles_.
[114] These facts have recently been observed and recorded
afresh by Mr. Clifford in _Nature Notes_, January 1893.
_Precautions against inquisitiveness._--I will finally quote a fact of
defence which took place under circumstances that were absolutely
exceptional, and which therefore exhibits genuine reflection in these
insects. During the first exhibition of 1855 an artificial hive was
set up, one face of which was closed by a glass pane. A wooden shutter
concealed this pane, but passers-by opened it every moment to
contemplate the work of the small insects. Annoyed by this
inquisitiveness, the bees resolved to put an end to it, and cemented
the shutter with _propolis_. When this substance dried it was no
longer possible to open the shutter. The bees were visible to nobody.
[Illustration: FIG. 43.]
[Illustration: FIG. 44.]
_Lighting up the nests._--An improvement of another nature in the
comfort of the dwelling is introduced by the _Baya_, and if the facts
narrated are correct they are the most marvellous of all. It is a
question of lighting up a nest by means of Glow-worms. The
_Melicourvis baya_ inhabits India; it is a small bird related to the
_Loxia_, already spoken of in this book. Like the latter it constructs
a nest that is very well designed and executed. (Fig. 43.) It suspends
it in general from a palm tree, but sometimes also from the roofs of
houses. In these shelters, woven with extreme art, are always to be
found little balls of dry and hardened clay. Why does the bird amass
these objects? Is it impelled by a collector's instinct less perfect
than that of the Bower-bird? There is no reason to suppose this. Nor
does it appear that he wishes to make the nest heavier and prevent it
by this ballast from being blown about by every breeze when the couple
are out, and the young not heavy enough to ensure the stability of the
edifice. The part played by these little balls is much more
remarkable, if we may trust the evidence of the natives, as confirmed
by competent European observers. Thus Mr. H. A. Severn writes:--"I
have been informed on safe authority that the Indian Bottle-bird
protects his nest at night by sticking several of these glow-beetles
around the entrance by means of clay; and only a few days back an
intimate friend of my own was watching three rats on a roof-rafter of
his bungalow when a glow-fly lodged very close to them; the rats
immediately scampered off."[115] These observations are confirmed by
Captain Briant, as reported by Professor R. Dubois.[116] In tropical
regions luminous insects give out a brilliant light, of which the
Glow-worms of northern countries can only give a feeble idea. These
flying or climbing stars are the constellations of virgin forests. In
South America the Indians utilise one of these insects, the _Cucujo_,
by fastening it to the great toe like a little lantern, and profit by
its light to find their road or to preserve their naked feet from
snakes. The first missionaries to the Antilles, lacking oil for their
lamps, sometimes replaced them by Fire-flies to read matins by.[117]
The _Melicourvis baya_ had already discovered this method of lighting,
and the mysterious little balls of clay were nothing more than
candlesticks in which these birds set Glow-worms, when they are fresh,
to act as candles. The entrance to the nest is thus luminous. (Fig.
44.) Apparently this lighting up is a defensive measure, for the birds
have nothing to do at night except to sleep, and must be rather
incommoded than cheered by this light. But the terrible enemy of all
broods, the Snake, is, it is said, frightened by this illumination,
which is able to penetrate the meshes of the nest, and will not dare
to enter. The system is ingenious, and the Roman Emperors, when they
used burning Christians as torches, were only plagiarising from this
little bird, which paves with martyrs the threshold of its house of
love.
[115] "Notes on the Indian Glow-fly," _Nature_, 23rd June 1881.
[116] _Science et Nature_, t. iv. (1885), No. 94, p. 232.
[117] P. Dutertre, _Hist. des Antilles francaise_, 1667.