My favourite woods were almost entirely of oak with a holly undergrowth, and at some points oaks were mixed with firs. They were never gloomy nor so silent as most woods; but in July, as a rule, one had to look for the birds, since they were no longer distributed through the wood as in the spring and early summer, but were congregated at certain points.
Mixed bird-companies
Most persons are familiar with those companies of small birds which form in woods in winter, composed of tits of all species, with siskins, goldcrests, and sometimes other kinds. The July gatherings are larger, include more species, and do not travel incessantly like the winter companies. They are composed of families—parent birds and their young, lately out of the nest, brought to the oaks to be fed on caterpillars. It may be that their food is more abundant at certain points, but it is also probable that their social disposition causes them to congregate. Walking in the silent woods you begin to hear them at a considerable distance ahead—a great variety of sounds, mostly of that shrill, sharp, penetrative character which is common to many young passerine birds when calling to be fed. The birds will sometimes be found distributed over an acre of ground, a family or two occupying every large oak tree—tits, finches, warblers, the tree-creeper, nuthatch, and the jay. What, one asks, is the jay doing in such company? He is feeding at the same table, and certainly not on them. All, jays included, are occupied with the same business, minutely examining each cluster of leaves, picking off every green caterpillar, and extracting the chrysalids from every rolled-up leaf. The airy little leaf-warblers and the tits do this very deftly; the heavier birds are obliged to advance with caution along the twig until by stretching the neck they can reach their prey lurking in the green cluster, and thrust their beaks into each little green web-fastened cylinder. But all are doing the same thing in pretty much the same way. While the old birds are gathering food, the young, sitting in branches close by, are incessantly clamouring to be fed, their various calls making a tempest of shrill and querulous sounds in the wood. And the shrillest of all are the long-tailed tits; these will not sit still and wait like the others, but all, a dozen or fifteen to a brood, hurry after their busy parents, all the time sending out those needles of sound in showers. Of hard-billed birds the chaffinch, as usual, was the most numerous, but there were, to my surprise, many yellowhammers; all these, like the rest, with their newly brought out young. The presence of the hawfinch was another surprise; and here I noticed that the hunger call of the young hawfinch is the loudest of all—a measured, powerful, metallic chirp, heard high above the shrill hubbub.
Caterpillars and ants
Watching one of these busy companies of small birds at work, one is amazed at the thought of the abundance of larval insect life in these oak woods. The caterpillars must be devoured in tens of thousands every day for some weeks, yet when the time comes one is amazed again at the numbers that have survived to know a winged life. On July evenings with the low sun shining on the green oaks at this place I have seen the trees covered as with a pale silvery mist—a mist composed of myriads of small white and pale-grey moths fluttering about the oak foliage. Yet it is probable that all the birds eat is but a small fraction of the entire number destroyed. The rapacious insects are in myriads too, and are most of them at war with the soft-bodied caterpillars. The earth under the bed of dead leaves is full of them, and the surface is hunted over all day by the wood or horse ants—Formica rufa. One day, standing still to watch a number of these ants moving about in all directions over the ground, I saw a green geometer caterpillar fall from an oak leaf above to the earth, and no sooner had it dropped than an ant saw and attacked it, seizing it at one end of its body with his jaws. The caterpillar threw itself into a horseshoe form, and then, violently jerking its body round, flung the ant away to a distance of a couple of inches. But the attack was renewed, and three times the ant was thrown violently off; then another ant came, and he, too, was twice thrown off; then a third ant joined in the fight, and when all three had fastened their jaws on their victim the struggle ceased, and the caterpillar was dragged away. That is the fate of most caterpillars that come to the ground. But the ants ascend the trees; you see them going up and coming down in thousands, and you find on examination that they distribute themselves over the whole tree, even to the highest and farthest terminal twigs. And their numbers are incalculable—here in the Forest, at all events. Not only are their communities large, numbering hundreds of thousands in a nest, but their nests here are in hundreds, and it is not uncommon to find them in groups, three or four up to eight or ten, all within a distance of a few yards of one another.
I had thought to write more, a whole chapter in fact, on this fascinating and puzzling insect—our "noble ant," as our old ant-lover Gould called it; but I have had to throw out that and much besides in order to keep this book within reasonable dimensions.
There is another noise of birds in all woods and copses in the silent season which is familiar to everyone—the sudden excited cries they utter at the sight of some prowling animal—fox, cat, or stoat. Even in the darkest, stillest woods these little tempests of noise occasionally break out, for no sooner does one bird utter the alarm cry than all within hearing hasten to the spot to increase the tumult. These tempests are of two kinds—the greater and lesser; in the first jays, blackbirds, and missel-thrushes take part, the magpie too, if he is in the wood, and almost invariably the outcry is caused by the appearance of one of the animals just named. In the smaller outbreaks, which are far more frequent, none of these birds take any part, not even the excitable blackbird, in spite of his readiness to make a noise on the least provocation. Only the smaller birds are concerned here, from the chaffinch down; and the weasel is, I believe, almost always the exciting cause. If it be as I think, a curious thing is that birds like the chaffinch and the tits, which have their nests placed out of its reach, should be so overcome at the sight of this minute creature which hunts on the ground, and which blackbirds and jays refuse to notice in spite of the outrageous din of the finches. The chaffinch is invariably first and loudest in these outbreaks; a dozen or twenty times a day, even in July and August, you will hear his loud passionate pink-pink calling on all of his kind to join him, and by-and-by, if you can succeed in getting to the spot, you will hear other species joining in—the girding of oxeye and blue tit, the angry, percussive note of the wren, the low wailing of the robin, and the still sadder dunnock, and the small plaintive cries of the tree-warblers.
Weasel and small birds
What an idle demonstration, what a fuss about nothing it seems! The minute weasel is on the track of a vole or a wood-mouse and cannot harm the birds. Yes, he can take the nestlings from the robin's and willow-wren's nests, and from other nests built on the ground, but what has the chaffinch to do with it all? Can it be that there is some fatal weakness in birds, in spite of their wings, in this bird especially, such as exists in voles, and mice, and rabbits, and in frogs and lizards, which brings them down to destruction, and of which they are in some way conscious? Some months ago there was a correspondence in the Field which touched upon this very subject. One gentleman wrote that he had found three freshly-killed adult cock chaffinches in a weasel's nest, and he asked in consequence how this small creature that hunts on the ground could be so successful in capturing so alert and vigorous a bird as this finch.
For a long time before this correspondence appeared I had been trying to find out the secret of the matter, but the weasel has keen senses, and it is hard to see and follow his movements in a copse without alarming him. One day, over a year ago, near Boldre, I was fortunate enough to hear a commotion of the lesser kind at a spot where I could steal upon without alarming the little beast. There was an oak tree, with some scanty thorn-bushes growing beside the trunk, and stealing quietly to the spot I peeped through the screening thorns, and saw a weasel lying coiled round, snakewise, at the roots of the oak in a bed of dead leaves. He was grinning and chattering at the birds, his whole body quivering with excitement. Close to him on the twigs above the birds were perched, and fluttering from twig to twig—chaffinches, wrens, robins, dunnocks, oxeyes, and two or three willow-wrens and chiffchaffs. The chaffinches were the most excited, and were nearest to him. Suddenly, after a few moments, the weasel began wriggling and spinning round with such velocity that his shape became indistinguishable, and he appeared as a small round red object violently agitated, his rapid motions stirring up the dead leaves so that they fluttered about him. Then he was still again, but chattering and quivering, then again the violent motion, and each time he made this extraordinary movement the excitement and cries of the birds increased and they fluttered closer down on the twigs. Unluckily, just when I was on the point of actually witnessing the end of this strange little drama—a chaffinch, I am sure, would have been the victim—the little flat-headed wretch became aware of my presence, not five yards from him, and springing up he scuttled into hiding.