In the centre of the wood I found a tree full of pigeons’ nests but for some odd reason devoid of pigeons. At the very top of the tree I noticed a great bundle of twigs and leaves which was obviously a nest of some sort and equally obviously not a pigeon’s nest. I wondered if it was the occupant of this rather untidy bundle of stuff that had made the pigeons desert all the nests in the tree. I decided to climb and see if the owner was at home. Unfortunately, it was only when I had started to climb that I realized my mistake, for nearly every pigeon’s nest in the tree contained eggs, and as I made my way slowly up the branches my movements created a sort of waterfall of pigeon eggs which bounced and broke against me, smearing my coat and trousers with yolk and bits of shell. I would not have minded this so much, but every single egg was well and truly addled, and by the time I had reached the top of the tree, hot and sweating, I smelt like a cross between a tannery and a sewage farm. To add insult to injury, I found that the occupant of the nest I had climbed up to was out, so I had gained nothing by my climb except a thick coating of egg and a scent that would have made a skunk envious. Laboriously I climbed down the tree again, looking forward to the moment when I would reach ground and could light a cigarette, to take the strong smell of rotten egg out of my nostrils. The ground under the tree was littered with broken eggs tastefully interspersed with the bodies of a few baby pigeons in a decomposed condition. I made my way out into the open as quickly as possible. With a sigh of relief, I sat down and reached into my pocket for my cigarettes. I drew them out dripping with egg yolk. At some point during my climb, by some curious chance, an egg had fallen into my pocket and broken. My cigarettes were ruined. I had to walk two miles home without a smoke, breathing in a strong aroma of egg and looking as though I had rather unsuccessfully taken part in an omelette-making competition. I have never really liked pigeons since then.
Mammals, on the whole, are not such good builders as the birds, though, of course, a few of them are experts. The badger, for example, builds the most complicated burrow, which is sometimes added to by successive generations until the whole thing resembles an intricate underground system with passages, culs-de-sac, bedrooms, nurseries and feeding-quarters. The beaver, too, is another master-builder, constructing his lodge half in and half out of the water: thick walls of mud and logs with an underground entrance, so that he can get in and out even when the surface of the lake is iced over. Beavers also build canals, so that when they have to fell a tree some distance inland for food or repair work on their dam, they can float it down the canal to the main body of water. Their dams are, of course, masterpieces – massive constructions of mud and logs, welded together, stretching sometimes many hundreds of yards. The slightest breach in these is frantically repaired by the beavers, for fear that the water might drain away and leave their lodge with its door no longer covered by water, an easy prey to any passing enemy. What with their home, their canals and their dams, one has the impression that the beaver must be a remarkably intelligent and astute animal. Unfortunately, however, this is not the case. It appears that the desire to build a dam is an urge which no self-respecting beaver can repress even when there is no need for the construction, and when kept in a large cement pool they will solemnly and methodically run a dam across it to keep the water in.
But, of course, the real master-architects of the animal world are, without a doubt, the insects. You need only look at the beautiful mathematical precision with which a common-or-garden honeycomb is built. Insects seem capable of building the most astonishing homes from a vast array of materials – wood, paper, wax, mud, silk and sand – and they differ just as widely in their design. In Greece, when I was a boy, I used to spend hours searching mossy banks for the nest of the trapdoor-spiders. These are one of the most beautiful and astonishing pieces of animal architecture in the world. The spider itself, with its legs spread out, would just about cover a two-shilling piece and looks as though it has been made out of highly polished chocolate. It has a squat fat body and rather short legs, and does not look at all the sort of creature you would associate with delicate construction work. Yet these rather clumsy-looking spiders sink a shaft into the earth of a bank about six inches deep and about the diameter of a shilling. This is carefully lined, so that when finished it is like a tube of silk. Then comes the most important part, the trapdoor. This is circular and with a neatly bevelled edge, so that it fits securely into the mouth of the tunnel. It is then fixed with a silken hinge, and the outside of it camouflaged with springs of moss or lichen; it is almost indistinguishable from the surrounding earth when closed. If the owner is not at home and you flip back the door, you will see on its silken underside a series of neat little black pinpricks. These are the handles, so to speak, in which the spider latches her claws to hold the door firmly shut against intruders. The only person, I think, who would not be amazed at the beauty of a trapdoor-spider’s nest is the male trapdoor-spider himself, for once he has lifted the trapdoor and entered the silken shaft, it is for him both a tunnel of love and death. Once having gone down into the dark interior and mated with the female, he is promptly killed and eaten by her.
One of my first experiences with animal architects was when I was about ten years old. At that time I was extremely interested in freshwater biology and used to spend most of my spare time dredging about in ponds and streams, catching the minute fauna that lived there and keeping them in large jam-jars in my bedroom. Among other things, I had one jam-jar full of caddis larvae. These curious caterpillar-like creatures encase themselves in a sort of silken cocoon with one end open, and then decorate the outside of the cocoon with whatever materials they think will produce the best camouflage. The caddis I had were rather dull, for I had caught them in a very stagnant pool. They had merely decorated the outside of their cocoons with little bits of dead water-plant.
I had been told, however, that if you remove a caddis larva from its cocoon and place it in a jar of clean water, it would spin itself a new cocoon and decorate the outside with whatever materials you cared to supply. I was a bit sceptical about this, but decided to experiment. I took four of my caddis larvae and very carefully removed them, wriggling indignantly, from their cocoons. Then I placed them in a jar of clean water and lined the bottom of the jar with a handful of tiny bleached seashells. To my astonishment and delight the creatures did exactly what my friend said they would do, and by the time the larvae had finished the new cocoons were like a filigree of seashells.
I was so enthusiastic about this that I gave the poor creatures a rather hectic time of it. Every now and then I would force them to manufacture new cocoons decorated with more and more improbable substances. The climax came with my discovery that by moving the larvae to a new jar with a new substance at the bottom when they were half-way through building operations, you could get them to build a parti-coloured cocoon. Some of the results I got were very odd. There was one, for example, who had half his cocoon magnificently arrayed in seashells and the other half in bits of charcoal. My greatest triumph, however, lay in forcing three of them to decorate their cocoons with fragments of blue glass, red brick and white seashells. Moreover, the materials were put on in stripes – rather uneven stripes, I grant you, but stripes nevertheless.
Since then I have had a lot of animals of which I have been proud, but I never remember feeling quite the same sort of satisfaction as I did when I used to show off my red, white and blue caddis larvae to my friends. I think the poor creatures were really rather relieved when they could hatch out and fly away and forget about the problems of cocoon-building.
Animal Warfare
I remember once lying on a sun-drenched hillside in Greece – a hillside covered with twisted olive-trees and myrtle bushes – and watching a protracted and bloody war being waged within inches of my feet. I was extremely lucky to be, as it were, war correspondent for this battle. It was the only one of its kind I have ever seen and I would not have missed it for the world.
The two armies involved were a
nts. The attacking force was a shining, fierce red, while the defending army was as black as coal. I might quite easily have missed this if one day I had not noticed what struck me as an extremely peculiar ants’ nest. It contained two species of ants, one red and one black, living together on the most amicable terms. Never having seen two species of ants living in the same nest before, I took the trouble to check up on them, and discovered that the red ones, who were the true owners of the nest, were known by the resounding title of the blood-red slave-makers, and the black ones were in fact their slaves who had been captured and placed in their service while they were still eggs. After reading about the habits of the slave-makers, I kept a cautious eye on the nest in the hope of seeing them indulge in one of their slave raids. Several months passed and I began to think that either these slave-makers were too lazy or else they had enough slaves to keep them happy.
The slave-makers’ fortress lay near the roots of an olive-tree, and some thirty feet farther down the hillside was a nest of black ants. Passing this nest one morning, I noticed several of the slave-makers wandering about within a yard or so of it, and I stopped to watch. There were perhaps thirty or forty of them, spread over quite a large area. They did not appear to be foraging for food, as they were not moving with their normal brisk inquisitiveness. They kept wandering round in vague circles, occasionally climbing a grass blade and standing pensively on its tip, waving their antennae. Periodically, two of them would meet and stand there in what appeared to be animated conversation, their antennae twitching together. It was not until I had watched them for some time that I realized what they were doing. Their wanderings were not as aimless as they appeared, for they were quartering the ground very thoroughly like a pack of hunting-dogs, investigating every bit of the terrain over which their army would have to travel. The black ants seemed distinctly ill at ease. Occasionally one of them would meet one of the slave-makers and would turn tail and run back to the nest to join one of the many groups of his relatives who were gathered in little knots, apparently holding a council of war. This careful investigation of the ground by the scouts of the slave-makers’ army continued for two days, and I had begun to think that they had decided the black ants’ city was too difficult to attack. Then I arrived one morning to find that the war had started.
The scouts, accompanied by four or five small platoons, had now moved in closer to the black ants, and already several skirmishes were taking place within two or three feet of the nest. Black ants were hurling themselves on the red ones with almost hysterical fervour, while the red ones were advancing slowly but inexorably, now and then catching a black ant and with a swift, savage bite piercing it through the head or the thorax with their huge jaws.
Half-way up the hillside the main body of the slave-makers’ army was marching down. In about an hour they had got within four or five feet of the black ants’ city, and here, with a beautiful military precision which was quite amazing to watch, they split into three columns. While one column marched directly on the nest the other two spread out and proceeded to execute a flanking or pincer movement. It was fascinating to watch. I felt I was suspended in some miraculous way above the field of battle of some old military campaign – the battle of Waterloo or some similar historic battle. I could see at a glance the disposition of the attackers and the defenders; I could see the columns of reinforcements hurrying up through the jungle of grass; see the two outflanking columns of slave-makers moving nearer and nearer to the nest, while the black ants, unaware of their presence, were concentrating on fighting off the central column. It was quite obvious to me that unless the black ants very soon realized that they were being encircled, they had lost all hope of survival. I was torn between a desire to help the black ants in some way and a longing to leave things as they were and see how matters developed. I did pick up one of the black ants and place him near the encircling red-ant column, but he was set upon and killed rapidly, and I felt quite guilty.
Eventually, however, the black ants suddenly became aware of the fact that they were being neatly surrounded. Immediately they seemed to panic; numbers of them ran to and fro aimlessly, some of them in their fright running straight into the red invaders and being instantly killed. Others, however, seemed to keep their heads, and they rushed down into the depths of the fortress and started on the work of evacuating the eggs, which they brought up and stacked on the side of nest farthest away from the invaders. Other members of the community then seized the eggs and started to rush them away to safety. But they had left it too late.
The encircling columns of slave-makers, so orderly and neat, now suddenly burst their ranks and spread over the whole area, like a scuttling red tide. Everywhere there were knots of struggling ants. Black ones, clasping eggs in their jaws, were pursued by the slave-makers, cornered and then forced to give up the eggs. If they showed fight, they were immediately killed; the more cowardly, however, saved their lives by dropping the eggs they were carrying as soon as a slave-maker hove in sight. The whole area on and around the nest was littered with dead and dying ants of both species, while between the corpses the black ants ran futilely hither and thither, and the slave-makers gathered the eggs and started on the journey back to their fortress on the hill. At that point, very reluctantly, I had to leave the scene of battle, for it was getting too dark to see properly.
Early next morning I arrived at the scene again, to find the war was over. The black ants’ city was deserted, except for the dead and injured ants littered all over it. Neither the black nor the red army were anywhere to be seen. I hurried up to the red ants’ nest and was just in time to see the last of the army arrive there, carrying their spoils of war, the eggs, carefully in their jaws. At the entrance to the nest their black slaves greeted them excitedly, touching the eggs with their antennae and scuttling eagerly around their masters, obviously full of enthusiasm for the successful raid on their own relations that the slave-makers had achieved. There was something unpleasantly human about the whole thing.
It is perhaps unfair to describe animals as indulging in warfare, because for the most part they are far too sensible to engage in warfare as we know it. The exceptions are, of course, the ants, and the slave-makers in particular. But for most other creatures warfare consists of either defending themselves against an enemy, or attacking something for food.
After watching the slave-makers wage war I had the greatest admiration for their military strategy, but it did not make me like them very much. In fact, I was delighted to find that there existed what might be described as an underground movement bent on their destruction; the ant-lions. An adult ant-lion is very like a dragonfly, and looks fairly innocent. But in its childhood, as it were, it is a voracious monster that has evolved an extremely cunning way of trapping its prey, most of which consists of ants.
The larva is round-bodied, with a large head armed with great pincer-like jaws. Picking a spot where the soil is loose and sandy, it buries itself in the earth and makes a circular depression like the cone of a volcano. At the bottom of this, concealed by sand, the larva waits for its prey. Sooner or later an ant comes hurrying along in that preoccupied way so typical of ants, and blunders over the edge of the ant-lion’s cone. It immediately realizes its mistake and tries to climb out again, but it finds this difficult, for the sand is soft and gives way under its weight. As it struggles futilely at the rim of this volcano it dislodges grains of sand which trickle down inside the cone and awake the deadly occupant that lurks there. Immediately the ant-lion springs into action. Using its great head and jaws like a steam-shovel, it shoots a rapid spray of sand grains at the ant, still struggling desperately to climb over the lip of the volcano. The earth sliding away from under its claws, knocked off its balance by this stream of sand and unable to regain it, the ant rolls down to the bottom of the cone where the sand parts like a curtain and it is enfolded lovingly in the great curved jaws of the ant-lion. Slowly, kicking and struggling, it disappears, as though it were being sucked down by quicksan
d, and within a few seconds the cone is empty, while below the innocent-looking sand the ant-lion is sucking the vital juices out of its victim.
Another creature that uses this sort of machine-gunning to bring down its prey is the archer-fish. This is a rather handsome creature found in the streams of Asia. It has evolved a most ingenious method of obtaining its prey, which consists of flies, butterflies, moths and other insects. Swimming slowly along under the surface it waits until it sees an insect alight on a twig or leaf overhanging the water. Then the fish slows down and approaches cautiously. When it is within range it stops, takes aim, and then suddenly and startlingly spits a stream of tiny water droplets at its prey. These travel with deadly accuracy, and the startled insect is knocked off its perch and into the water below, and the next minute the fish swims up beneath it, there is a swirl of water and a gulp, and the insect has vanished for ever.
I once worked in a pet-shop in London, and one day, with a consignment of other creatures, we received an archer-fish. I was delighted with it, and with the permission of the manager I wrote out a notice describing the fish’s curious habits, arranged the aquarium carefully, put the fish inside and placed it in the window as the main display. It proved very popular, except that people wanted to see the archer-fish actually taking his prey, and this was not easy to manage. Eventually I had a brainwave. A few doors down from us was a fish shop, and I saw no reason why we should not benefit from some of their surplus bluebottles. So I suspended a bit of very smelly meat over the archer-fish’s aquarium and left the door of the shop open. I did this without the knowledge of the manager. I wanted it to be a surprise for him.
It was certainly a surprise.
By the time he arrived, there must have been several thousand bluebottles in the shop. The archer-fish was having the time of his life, watched by myself inside the shop and fifty or sixty people on the pavement outside. The manager arrived neck and neck with a very unzoological policeman, who wanted to know the meaning of the obstruction outside. To my surprise the manager, instead of being delighted with my ingenious window display, tended to side with the policeman. The climax came when the manager, leaning over the aquarium to unfasten the bit of meat that hung above it, was hit accurately in the face by a stream of water which the fish had just released in the hope of hitting a particularly succulent bluebottle. The manager never referred to the incident again, but the next day the archer-fish disappeared, and it was the last time I was allowed to dress the window.