Nature Writing

I have just uploaded this title to Smashwords. Here is the Introduction:

My enthusiasm for natural history was probably first sparked by Richard Jefferies, whose Bevis fevered my imagination for two or three months in 1962, when I was twelve. My recreational reading consisted thereafter mostly of books about nature. Many of these I bought with my pocket money, so they tended to be second-hand and out of date.

British nature-writing reached its heyday in the late nineteenth century. The drift to the cities had produced a rich vein of nostalgia for the countryside, and this was assiduously mined by the publishers of the day. Besides essayists like Jefferies and W. H. Hudson there were any number of authors who produced handbooks of the flora and fauna. All these books were written in a formal style and edited to Victorian standards of literacy. I didn't realize it at the time, but they were having a profound influence on the way I produced, and was ever to produce, written English.

Nature as a subject for a child's pen is ideal: it is inexhaustible. There is also scope for original observation and plain description, especially if the child is lucky enough to have been born into a literate household and attends a school whose teachers have high expectations of their pupils.

The first part of this collection comprises a series of articles published during 1984-5 by a local newspaper in my home town, Watford, on the outskirts of north-west London. After these are four short pieces I wrote purely for pleasure. These begin with Hunting Sparrowhawk.

Finally I provide a series of brief extracts – often no more than a sentence or two – from the nature journal I have been keeping since 1963. Read in sequence, these provide a curious picture of a boyish enthusiasm gradually maturing. They also give a glimpse of a disappearing world. Alas, my old school is by no means what it was, children are no longer free to wander the woods and wild seashore at will, and the English countryside is even more degraded now than it was then.

This ebook contains all the "Natureview" pieces published on this blog, together with some other essays and a selection of excerpts from my personal nature journal from 1963 onwards.

Moles

Image: Kókay Szabolcs

The onset of the frosts often brings signs of renewed mole activity, especially on pastureland. One morning it seems that freshly turned molehills are everywhere. There appears to be no pattern to them; an army of excavators has been at work; but if carefully studied it emerges that the heaps usually belong to a single burrow system inhabited by a single mole.

The “moudiewart” is not much of a socializer. Except when male and female briefly meet, of necessity, in the early spring, any encounter between moles usually leads to a fight, often vicious, and sometimes to the death. They are subterranean hermits, irascible and solitary. Their world, just a few inches underfoot, is quite bizarre; and they are wonderfully adapted to it.

Few people have seen a dead mole, never mind a live one, but of those who have, most are surprised by its smallness. A really big buck, so called, is no more than five and three-quarters inches long and tips the scale at something under five ounces.

Yet, for its size, the mole is one of the world’s strongest animals. In just twenty minutes it can evacuate as much as ten pounds of soil, or fifty times its own body-weight. A twelve-stone miner would have to shift four tons in the same period to work at a corresponding rate.

To fuel this tremendous effort, moles have a voracious intake of food, consuming about half their own weight every day. The main item of diet is the earthworm, but other soil invertebrates like slugs and leatherjackets are taken too.

The burrow system serves to trap whatever stumbles into it. The mole makes regular patrols, snapping up food as he finds it. When caught, a worm is seized with the jaws and pulled through the huge forelimbs in a special way, which cleans it of much external dirt and at the same time helps to void the contents of its gut. This done, the worm is either devoured in a matter of moments; or, in some circumstances, bitten in the head, to immobilize it, and stored to be savoured later. A mole’s pantry may contain many worms: the record is 470, weighing almost two pounds!

Periods of frenetic activity lasting about four and a half hours alternate with periods of about three and a half hours in the nest, sleeping it off. The cycle goes on regardless of day or night.

Some foreign species of mole are completely blind, with the eyes not only reduced but actually covered with skin. Our mole has not quite reached this stage. If you blow gently, you can part the plush pile of the fur to reveal tiny bead-like eyes. They can just distinguish light from dark, but probably not much else.

Nor is hearing of great importance. The external ear has gone altogether – it would only get in the way during burrowing – and the internal ear is not specially well developed. Taste and smell are also rather rudimentary.

Of much more interest are the mole’s other senses. It is keenly sensitive to touch, and can detect minute vibrations in the soil. Groups of tactile hairs are found on the chin and muzzle and the tip of the tail. The snout, pink and hairless, is covered with thousands of papillae called Eimer’s organs. These are specially sensitive, particularly when the slightly erectile tip of the snout is gorged with blood.

The function of these Eimer’s organs is not really known. They certainly register subtle changes in touch, and perhaps in smells too. They may also be affected by changes in temperature and infra-red radiation, enabling the mole to “see” in the dark.

Even more remarkably, it has been suggested that Eimer’s organs might also work as “teletactile receptors”, sensitive to minute changes in air pressure. By this means the mole could tell at a distance when it was approaching an obstacle or even a prey animal. The vibrissae may also help the mole to detect compression waves in the air, and certainly warn it of approaching obstacles.

If a mole’s senses are well adapted to the underground life, his anatomy is better adapted still. A mole is a digging machine, a furry bulldozer purpose-built for the job. The whole animal is tube-shaped. Its skeleton is heavily reinforced for attachment of the digging muscles and to allow free rotation of the shoulders, which are powerful and relatively massive. The forepaws are developed into efficient shovels, fitted with strong claws.

Put down on almost any surface but concrete, paving, or asphalt, a mole will immediately dive into the ground. A breast-stroke action is used, frenziedly repeated until the tip of the tail vanishes. Once underground the mole progresses with alternate motions of either forepaw, the other being used, together with the hind feet, as a brace.

In soft earth the spoil may simply be compacted into the sides of the tunnel, but in firmer ground it is ejected at intervals through specially made vertical shafts, and forms the molehills which are the bane of gardeners and greenkeepers. Sometimes, in very soft soil, moles make tunnels so close to the surface that the ridges may be clearly seen.

If he is lucky, a young mole will inherit a tunnel system ready-made, but often as not he has to start, so to say, from scratch. The construction of a complete tunnel system is a colossal task. Without seeking planning permission, tendering for contract, putting up a signboard, or bothering with a starting ceremony, the mole just gets on with it.

The system always incorporates a nest, a spherical chamber lined with hay and leaves. Here the mole sleeps, or if she is pregnant, gives birth to the tiny pink molelets. In places liable to flooding, the nest may be sited in an abnormally large molehill. These big hills, or fortresses, can be a foot high and a yard across.

Once the basic system is dug, it is refined and enlarged with other tunnels, crossing and branching and on a variety of levels. From then on most of the mole’s work consists of keeping it clear of obstructions.

When the weather turns cold, the mole moves into deeper tunnels which might not have been used since the spring. Repairs and alterations produce spoil; and it is this spoil that appears above the ground at the start of frosty weather – as sure a sign as any of the coming winter, and an outward clue that matters proceed in the industrious, hermitic life of the mole.

(Introduction to these pieces; see all)

This is the last of the Natureview pieces suitable for reproduction here. I hope you have enjoyed at least some of them.

Richard

Leaf-fall

Image: Lukas Riebling

All but one of our native British trees are deciduous, shedding in a few weeks of autumn their canopy of leaves. The leaves contain green chlorophyll, held in bodies known as chloroplasts. It is in the chloroplasts that the main business of the tree is carried out – photosynthesis, the manufacture of sugars and other organic compounds, using carbon dioxide, water and trace elements, the whole reaction being powered by sunlight.

As much attention to detail is lavished on an individual leaf as on the whole tree. Each one is a miracle, a factory filled with chloroplasts. To work properly the chloroplasts must be kept wet, so the leaf is enveloped in a waterproof envelope and air is only allowed to enter through special pores which can be opened or closed at will.

Then of course the products of the chloroplasts must be conveyed to the rest of the tree, and waste matter taken away, so the leaf is provided with a complete network of veins.

When you think how many leaves are put out each spring by, for example, an oak tree, it seems an insane act of wastefulness to throw them away again at the end of the summer. Yet, such is the cost of maintaining a broad leaf in working order during unfavourable weather that it actually pays the tree to adopt the deciduous habit if its leaves are of that type.

In equatorial forests most broad-leafed trees keep a perpetual canopy of foliage, shedding leaves in small numbers all the year round. The same is done here in the temperate zone by a few broad-leafed trees, like the evergreen oaks, and the world over by pines, spruces, and the other “official” evergreens. In fact all trees everywhere regularly shed leaves which have reached the end of their working lives. Looked at like this, the autumn leaf-fall does not seem quite so profligate.

If a branch is killed, the leaves merely wither. They do not fall: the autumnal leaf-shedding is a carefully controlled operation, involving the least possible loss to the plant. Preparations for it have been going on since the summer.

Whenever a plant deliberately sheds an organ – be it a leaf, a petal, a whole flower, a fruit – a special separation layer is formed where the split is to take place. The layer is made of cells with an inherently weak jelly-like middle. Meanwhile, below this the tree forms a sealing layer which will keep out bacteria and fungal spores when the separation finally comes.

As the growing season reaches its end, the tree reclaims whatever it can from the leaf. Valuable trace elements are resorbed. The chloroplasts are gradually allowed to die, losing their green colour. The delicate conducting vessels which, all summer, have carried sugars out of the leaf, are one by one shut down and their point of entry into the system sealed off. All that remains are the tougher, woodier, water-conducting vessels.

Having lost its chlorophyll, the leaf is given colour by its residual pigments. Chief among these are xanthophylls and carotenes, which have an important job to play in the chemistry of the leaf. The autumn yellow of, say, the birch or sycamore is solely due to these.

There are other pigments, too. The golden yellow of beech leaves is produced by a brownish pigment, probably tannin, which is present in addition to the xanthophylls and carotenes. The more promiment reds and purplish-browns of the autumn woods come from a group of compounds called anthocyanins – which also give the red, purple or blue colour to many flowers.

The best autumn pageant comes only when the weather promotes the development of anthocyanins, when there are extended periods of bright, clear, dry weather with cool but not freezing night temperatures. This weather is the norm in autumn in New England, where the display of maples, oaks, and cherries attracts large numbers of admiring visitors every year.

The display in our own woods and gardens is not bad, either. Our native trees have a marvellous range of yellows, reds, and browns. The beech, of which different individuals turn at different times, offers perhaps the most beautiful show of colour, but such trees as the field maple, willow, rowan, and wild cherry can sometimes put in a really glorious performance. Then there are all the introduced trees, many of which have some fine autumn tints.

By the time the leaves are at this stage the whole metabolism of the tree has undergone a profound change. The hormonal balance – for plants, like animals, control their tissues with hormones – has tipped in favour of the dormins, a group of compounds prominent, as their name suggests, in the dormancy of seeds and buds. The growth-promoters of late winter and spring have been largely replaced by growth inhibitors. There is a build-up of these compounds in the area of the separation layer.

A leaf on the point of falling is held in place only by its separation layer, its outer skin, and the woody water-conducting vessels in the middle of the leaf-stalk. Wind and gravity between them work to free the leaf’s hold; the end often comes after a hard frost, which freezes the jelly-like middle of the separation layer, making it expand and forcing the cells apart.

Each breeze then thins the foliage, revealing more and more of the winter skein of twigs. The tree, the sugar factory, has shut down until spring: but next year’s leaves are already formed, crammed into buds.

When they reach the ground the old leaves are seized upon by an army of invertebrates and broken down into rich soil ready for future generations of leaves, and for future generations of trees and for all the other plants and animals that depend on them. So in the end nothing, really, is wasted after all.

(Introduction to these pieces; see all)

Sleeping Rough

Image: Matthew Woitunski

In Cassiobury Park at dusk I noticed a man of middle years, a little way ahead, making a slow and strangely aimless progress under the trees. Dressed in a dark overcoat and of outwardly normal appearance, it was at once apparent that he was anything but normal. His very walk betrayed him as one of society’s misfits, mentally or socially deficient, unable to make sense of the crazy set of rules devised by the rest of us. He had the air of utter solitude, the desolation and loneliness that mark the tramp: and a moment later he stooped to examine a discarded cigarette packet.

There are others sleeping rough in the park and woods. Occasionally, in out-of-the-way places, their shelters may be found: comfortless lairs of brushwood and polythene, with a cache of empty old tins and packets nearby.

Our own shelters are scarcely more permanent. We are separated from the wilderness only by the thickness of a pane of glass. Out there, as the winter begins to bite, conditions at night are frequently lethal for the soft, warm, high-tech machinery of our bodies.

The human animal evolved in the tropics, and is designed to work best in tropical temperatures. As man slowly migrated northwards he had to adopt new strategies for survival. The endless forests of temperate Europe teemed with game: the trade-off between cold and hunger was well worth the effort.

First he lost most of the pigment in his skin. It was no longer needed to protect the body from too much ultraviolet radiation, and even proved a handicap, for much of the body’s vitamin D is produced by the action of sunlight on the skin.

To help with heat insulation, he became more hairy. Of more importance, he developed the practice of wearing clothes, using the pelts of prey animals. Clothes are as old as northern man himself: the arguments of nudists that it is more natural to go without them in these latitudes are utterly fallacious.

The most important asset of all was fire. The earliest true men, belonging to a species called Homo erectus, used to keep a fire burning perpetually. Probably one member of the tribe was charged with tending it; when on the move, the fire was nurtured in the form of smouldering embers.

The capture and taming of fire represents one of the key feats in man’s mastery of the environment. It must have happened independently many times and in many places over aeons of time. Fire occurs spontaneously in nature, often following a lightning strike. It has no substance, yet gives pain and destroys. Its forms and colours are those of a spirit. Early men must have viewed it with terror.

But they must also have noticed how a bush fire drives the game before it, and must have taken advantage of the opportunities spontaneous fires gave. Any animal which died in the fire and was part roasted would have been eaten too, and they would have noticed with pleasure how much better this flesh tasted and how much easier it was for them to eat.

Then, sooner or later, one individual, more daring than the others, made the leap of imagination that even then was the stamp of genius.

The invention of friction-fire is even more remarkable. As any Boy Scout will tell you, it’s not just a question of rubbing two sticks together. Lighting a fire by friction is a difficult operation, as well as being hard work.

Another brilliant invention – the bow and arrow – gave rise to the bow-drill, in which the string of the bow is looped once round a stick. If the top of the stick is then held in place using a slightly hollow pebble, and the bow worked back and forth, the stick revolves at high speed. Result: smouldering punk-wood in a few moments, fire in a few moments more.

With ready fire and warm clothing, man moved ever northwards. The Inuit, whose unique way of life is now becoming a thing of the past, reached the ultimate in ingenuity with their igloos, houses made of snow itself.

The ingenuity of our ancestors in southern England led to winter pit-dwellings which must have been extremely cosy. Excavations at Stone Age campsites show an impressive degree of co-operation and skill in the construction of these pits. Roofed with branches and ferns and lined with skins, such a house would be occupied by a whole family group. Each occupant acted as a radiator, and after a very short time the interior temperature would be well up into the comfort zone.

In building these dwellings, as in a vast range of other techniques, the people who used to roam this landscape were experts at survival. Nearly all their skills depended on mutual co-operation and division of labour within the tribe. Solitude for a Stone Age man meant certain death, and probably, as in some primitive tribes still clinging on today, expulsion was the ultimate punishment.

The unfortunates sleeping rough in modern Britain have none of ancient man’s knowledge, nor can they draw on the inexhaustible supply of food the forest provided. Whippendell Wood would barely support even one family. The ecosystem has effectively been wrecked: the tramp must depend on the grocer’s shop along with the rest of us.

The grocer’s shop relies on an agriculture which would be virtually impossible without chemicals. If for some reason the supply of chemicals ceased, the whole structure of our society would collapse.

The old and unfit would simply die. For the rest, the black-and-white laws of survival beyond the window-pane, now faced only by the tramp, would become the new reality.

On an early-autumn night, that is a sobering thought indeed.

(Introduction to these pieces; see all)

Fungi

Lamellae of Amanita muscaria

Image: W.J.Pilsak

Most English people instinctively fear and dislike fungi, and waste no opportunity to kick a toadstool to bits. A native of the continent, especially of eastern Europe, would find such behaviour quite mad, and would no doubt add it to the long list of eccentricities for which we are internationally renowned.

In all lands but this, wild fungi are gourmet fare. But here we eat only the insipid mushrooms that come in a safe plastic punnet, and leave the best to rot. Of all the hundreds of sorts of mushrooms and toadstools to be gathered from our fields and woods, only a few are dangerously poisonous. A large number will give you indigestion, even more are tough, tasteless, or otherwise inedible, but many of the rest are absolutely delicious.

Unfortunately it takes detailed knowledge to decide which are safe to eat. There is no general rule, no substitute for knowing each species – and its lookalikes – well. In England we have no tradition of such learning passed down from parent to child. What knowledge we have must usually come from books.

Overcoming this English phobia and finding wild mushrooms for the table often leads on to an interest in the fungi themselves. More than an interest: a fascination, an obsession. A walk in the woods becomes a treasure-hunt. The fungus-seeker’s eyes are rarely raised from the ground, unless it is to scan the boughs overhead for bracket growths.

Fungi are now classified into their own kingdom, quite distinct from those of plants or animals. They are far stranger than any Martians. The range of forms and colours, of smells and textures and tastes, and of strategies for survival, shows a boundless cosmic imagination at work.

The majority of the world’s 50,000 or more named fungi are microscopic. They have colonized almost every conceivable habitat, from pigeon droppings to the fuel tanks of Concorde. In a single teaspoonful of garden soil there may be as many as 2 million individual fungi existing either as spores or in active growth.

All but the single-celled fungi are built to the same basic plan, being made up of hollow filaments called hyphae. The hyphae combine in a mass, the mycelium, which constitutes the body of the fungus. In a field mushroom, for example, the mycelium lies mostly underground as a network of threads; the mushrooms themselves are the fruiting bodies of the fungus and of course only appear at certain times when conditions for spore dispersal are favourable.

A toadstool is a masterpiece of design, custom made for the job of spreading as many spores as possible. This it does in various ways, depending on the group to which it belongs. In the gill fungi, which includes many of the larger and more familiar mushrooms and toadstools, the gills are covered with tiny club-shaped projections called basidia. Each basidium carries four minute stalks, with a spore on the end of each one.

A mushroom with a 10-centimetre wide cap has a gill area of some 1200 square centimetres. During an active life of 5 or 6 days, it will release something like 16,000 million spores – an average fall, day and night, of over 30,000 per second. Each of these spores is discharged in an ordered manner. Pressure is steadily increased at the point where the spore is attached to its stalk. The mechanism is not yet fully understood: but when the spore is discharged, it shoots away from the stalk to a distance of about 0.1 mm, or about 15 times its own length.

Then, falling down between the gills, it is carried away on air currents. Even the lightest movement is enough to bear it away. The other three spores on each basidium are shot off at intervals of a minute or so.

In order to achieve a free flow of spores, ripe basidia are evenly distributed among discharged ones and among those that are yet to fire. Both the stem and the cap respond to gravity, keeping the gills perpendicular to the ground and minimizing the chance of a spore sticking to an adjacent gill. The gills themselves are spaced and arranged for maximum efficiency. And, finally, most gill fungi take care to fruit in the autumn, when winds are strong, temperatures are right, and the weather is ideally damp.

Unlike green plants, fungi have no chlorophyll and so cannot make their own food. They must get it from other sources. Some fungi are symbionts, growing on or in other living organisms (even other fungi); some are saprotrophic, feeding on dead material. Symbionts may be of benefit to the host, or may weaken and eventually kill it, in which case the fungus may itself die or switch to saprotrophy. The distinctions are not always clear-cut.

The usual mode of feeding is via the hyphae, which ramify into a network invading the food source. Hyphae secrete chemicals which break down the food and allow it to be absorbed. The variety of things which fungi can use as food is staggering. Virtually any organic material – even the kerosene in Concorde’s tanks – can be grist to their mill. Without them, much of the decay in the world would be not happen and life for other forms would be difficult if not impossible.

Most of the larger fungi belong to an advanced group called the basidiomycetes (those fungi having basidia), and it is usually with this group that an interest in, even a love for, fungi begins.

The fungus fanatic could have no happier hunting-ground than Whippendell Wood, near Watford. The fungus flora there is so rich that during just a few visits I found well over 100 different species, and I would by no means call myself an expert. The commonest sort overall is one named Russula ochroleuca, with white stalk and gills and a yellowish cap, found growing singly or in small parties in the leaf litter under trees. Among the others are several of the most poisonous species known to man, and some of the most tasty.

Next time you take a walk in the woods – and what better month for that than October? – spare a minute to look at some fungi. Even if you’re not sure of their names, you may find that the previously despised, overlooked, and, perhaps, kicked to bits, is admirable after all and, in its own peculiar way, both impressive and beautiful.

(Introduction to these pieces; see all)

Collared Doves

Image: Horia Varlan

The practice of keeping dovecots is now largely a thing of the past, which is rather a shame, because a few white doves add greatly to the charm of a garden or courtyard. Better than domestic doves, though, are those born and bred to the wild. They make ideal “pets”, because they are free to leave at any time, and there is none of the compulsion which to my mind mars the usual relationship of human with animal.

Unless you are very unlucky, you will have your own wild doves – Collared Doves – not too far away: slender, stone-coloured birds with a distinctive cooing song. They are fond of suburban back gardens, smallholdings, farmyards, and similar places, and where unmolested can become quite tame.

At a distance a Collared Dove looks almost uniformly greyish brown, but seen close to, especially in sunshine, it is a most elegant and attractive bird. The plumage is very delicately contoured and shaded, and a softly vinous flush on the breast harmonizes perfectly with the claret-coloured legs and feet. The eye, too, is in this register of red: when the sun catches it at a certain angle, it looks exactly like a ruby.

In its flight and habits the Collared Dove is a gentle, fastidious creature; the partial black collar, edged with white, is reminiscent of the velvet chokers once worn by dowager duchesses. The impression is completed by one of the bird’s often-used calls, a loud uhrrr, uhrrr! uttered as if in horror at the violation of its genteel sensibilities by the appearance of some unspeakably uncouth ruffian – perhaps even a flasher.

The Collared Dove has become so much a part of the local scene that it is hard to believe it bred in this district no earlier than 1966. The first arrivals were the subject of a series of excited notes on a brand-new card in my index box. The magic date was 25 May 1966, when a male was seen – studied at 30x through my telescope! – and heard singing on the roof of the house. By 4 June it had a mate and both birds remained in the area till the end of the year. Definitely not a domesticated form. Very good views frequently obtained when seen drinking from gutter 15’ from window. Wary and unapproachable.

Few bird-watchers now would bother to record “very good views” of the Collared Dove. But how and why has this bird become so common where previously it was unknown?

Nothing is ever static in the living world. Even the most apparently stable community of plants and animals is in perpetual flux, brought about by changes in climate or other environmental factors, or by changes in their own genetics and evolution. Change is in fact one of the chief characteristics of living things.

Normally this change is quite slow, taking the span of many human lifetimes to become obvious. Sometimes, though, it can be quite rapid, and occasionally, as in the case of the Collared Dove, it can be spectacular.

The most sudden changes come in the wake of some catastrophe, a natural disaster such as a forest fire, an earthquake, or volcano, which wipes out one community and gives a clean slate for the formation of another. Or the natural disaster may simply destroy one part of the community and alter its balance, allowing certain new forms to invade.

Man’s influence on the environment can be seen as a series of natural disasters, both large and small, of this second type. Many species have lost out; some have gained from the opportunities inadvertently put in their way. When a species not only has a new set of opportunities put before it, but simultaneously undergoes a genetic or behavioural change enabling it to exploit new territory, then you can expect some fireworks.

The Collared Dove was originally a bird of the Indian sub-continent. Its principal food is grain, which pre-adapted it to benefit from Man’s increasing use of agriculture. As farming slowly became more successful the Collared Dove began to spread slowly north and west, reaching Asia Minor in the 16th century. By 1925 it was well established in the Balkans.

Then, suddenly, something happened. It may have been a slight genetic change enabling some individuals to breed more successfully; it may have been a behavioural change making the Collared Dove even more tolerant of Man. Whatever did happen, the slow northward expansion of the previous few centuries became a full-scale invasion.

A record of its progress across Europe looks like one of those animated maps showing the advance of the Nazis: from Belgrade it reached Hungary in 1928 and Czechoslovakia in 1935. Austria fell in 1938, Poland in 1940. It reached Germany and Italy in 1944, Holland in 1947, Switzerland and Sweden in 1949. By 1950 it was breeding in France: the first (unofficial) British sighting was in 1952, the first breeding record in Norfolk in 1955. It first bred in the London area in 1962, and in our own district, as already mentioned, in 1966.

The earliest colonists were often to be found in the vicinity of chicken-runs, or at zoos or other places where spilled or otherwise free grain was to be picked up. This opportunism in feeding is one key to the Collared Dove’s success. Another is its liking for conifers in which to nest – almost to order we busily planted our suburbs with Lawson’s Cypress, ready for its arrival.

But the main key to its success is its fecundity. In mild weather the breeding season may begin as early as January and go on till October. It can tend the young of one brood while incubating the eggs of the next, and will tolerate levels of disturbance that would make most other birds desert.

The increase is still going on. In Britain it is extending its range into other habitats, especially farmland. Abroad it is still moving north and west, having reached Iceland, where this gentle invader may even be readying itself for the final, really big challenge, the one that even the Nazis couldn’t get near: Canada, the USA, and all points south.

(Introduction to these pieces; see all)

Aristocrat Butterflies

Proboscis of Peacock Butterfly, Inachis io

Image: Ian Dury

The fermenting juice of rotting windfalls brings many wasps and flies, the odd hornet, and, with luck, butterflies. If nearby there are also September flowers – especially Michaelmas daisies and buddleia blossom – the chance of butterflies is increased still more.

By this time of year the majority of butterflies still on the wing are those that spend the winter as adults, rather than as eggs or larvae or pupae. Typical of this group are certain members of the nymphalids, a family which contains some of the showiest and best-known British butterflies, such as the Peacock, the Red Admiral, the Comma, and the Small Tortoiseshell.

So entranced were the early lepidopterists by this family that they called many of its children the “aristocrats” and gave them names to match. The Purple Emperor, the White Admiral (the word Admiral is a corruption of “Admirable”), the Camberwell Beauty, and the Large Tortoisehell are rare in England today. A frequent cause of a butterfly’s decline is increasing scarcity of the plant or plants on which its caterpillar feeds. In the case of the Large Tortoiseshell, for example, the major food plant is elm, and, through Dutch elm disease, we have lost twenty-five million trees since 1970.

But not all is gloom. Many sorts of insects – a number of aristocrats among them – depend either partly or completely on the nettle for food and shelter. The nettle is highly nutritious for hungry caterpillars and, best of all, avoided by grazing animals. It is usually found in association with man, thrives on waste ground, and may be locally abundant.

The Red Admiral, the Peacock, the Small Tortoiseshell and the Comma are all partial or exclusive nettle-feeders, so it is no surprise that these are the aristocrats commonest today. The Comma – a tawny butterfly with its jagged-edged wings spotted with black – has in fact been increasing its numbers since about 1925, for reasons not fully understood.

The Comma gets its name from a small, comma-shaped mark in silvery white on the underside of each hind wing. The rest of the undersides are camouflaged with brown and darker brown pencillings, so cleverly that when a Comma closes its wings it can seem to disappear. Its caterpillar, which leads a solitary life, goes one better in the camouflage game and looks very much like a bird dropping. The adult butterfly is often seen in gardens, where it may form an attachment to a small area – sometimes of just a few yards square – with its own favourite leaves for resting and basking in the sun.

The Peacock and the Small Tortoiseshell also have drab, disguised underwings which contrast with the ostentatious patterns above. The Small Tortoiseshell, marked with orange, brown, contrasting patches of black and white, and with a tracery of tiny blue half-moons along each trailing edge, is perhaps the most familiar of the garden aristocrats.

The Peacock is almost as common. It is so called from its four large “eyes”, the ones on the hind wings being especially like those on peacock’s feathers. The colouring and texture of its wings are almost unbelievably subtle and complex, more inventive and in far better taste than even the most costly Oriental carpet. However long you study a resting Peacock, always apprehensive that at any moment it will decide to flit away, your eye can never take it all in; the brain can remember no more than the crudest essentials of the pattern.

It is no answer to catch and kill the insect and pin it to a board, for then, with its life, its vibrancy is lost and the colours seem to fade. Butterflies must be admired in their totality, and that includes sunlight and air and the liberty to fly away.

The fruit-strewn turf of a neglected orchard is a fine place to see Red Admirals. Drunk on cider and greedy for more, they are more approachable than usual. The wing-pattern is predominantly black, with a scarlet band across each forewing, another on the trailing edge of each hind wing, all offset by white splashes and touches of azure. As it sips the sweet, intoxicating juice the butterfly continually opens and closes its wings as if in ecstasy. The scene is almost one of decadence. In places two or three Red Admirals jostle with Peacocks and wasps for the best places on the decaying fruit.

This taste for decay is reminiscent of some of the really big tropical butterflies which flock to putrefying carrion. At one time Purple Emperors were baited with dead rabbit; besides rotting fruit, the Red Admiral likes the rich sap oozing from damaged oak trunks.

The Red Admiral, like several other nymphalids worldwide, is a migrant. It arrives in May, having flown here from North Africa or Southern Europe, and lays its eggs, singly, on the upper surface of nettles or related plants. These eggs give rise to the resident summer generation; some of the butterflies feeding in the orchard may be on a return migration, for the Red Admiral is unable to withstand the northern cold and does not hibernate north of the Alps.

The Peacock, the Comma, and the Small Tortoiseshell, though, are able to withstand it, and in the next few weeks will be seeking safe places to hide for the winter. With their wings closed, leaving only the camouflaged undersides showing, they are easily missed by predators. They are also easily missed by humans: when giving the garden shed its autumn turn-out it is worth remembering that some of these butterflies may well have staked their all on a crack or crevice in some dark corner.

There they remain, month after month, motionless and with their body functions almost at a standstill. A few warm days in March are enough to wake them, which is why Peacocks or Small Tortoiseshells are among the first butterflies to be seen in spring. Then there is no rotting fruit to attract them; they must break their fast with a purer nectar sipped from banks of heather or other early blooms.

It might be preferable to think of them at that spring, rather than this autumn, equinox, and, tiptoeing a retreat through the dew-soaked grass, leave the orchard and its inhabitants to their orgy of decay.

(Introduction to these pieces; see all)

Black-headed Gull

Image: Gidzy

As summer comes to its close, the annual influx of gulls gathers pace. By autumn they are everywhere in the district, feeding on pasture and arable and parkland, by and on water of all kinds, and, ever on the lookout for a meal, patrolling the skies above back gardens and industrial sites.

There are five common sorts which visit us here, and the commonest of these is the black-headed gull. This is the smallest and the slenderest of the five, and can be told by its red bill and legs, and the long white triangle on the leading edge of the wings, which have pointed rather than rounded tips.

Despite its name, the black-headed gull’s head is not black. In spring and summer the adult has a chocolate-brown hood, which is moulted in autumn to leave the head pure white except for two dark smudges, the larger one behind the eye and the smaller one just in front of it. The immature bird is more mottled in appearance, but still has the white triangles on the wings and, at all seasons, the smudges on the head.

In grace, buoyancy, and agility of flight the black-headed gull has few equals among our winter birds. During autumn it makes a habit of following the plough, and a hundred or more at a time can be seen swirling like snowflakes against the freshly turned soil. The same sort of prey – wireworms, millipedes, earthworms, and so on – attracts it to football fields and similar grassland; but our local black-headed gulls find their shangri-la on pasture that has just been sprayed with Hydig, the fertilizing sludge produced at Maple Cross sewage works, just south of Rickmansworth.

The sewage works themselves are also an attraction for gulls. In the grounds is a disused gravel pit which, during the 1960s, was filled with solid matter rejected during the purification process. A long black outfall pipe led from the works into the middle of the pit. Some of the outfall consisted of sand, so that the pit slowly became silted up, but it also contained grain, as well as a comprehensive assortment of the things that get dropped or thrown into the lavatory (among them many children’s toys such as rubber Donald Ducks, combs, nailbrushes, pairs of spectacles, and any number of sets of false teeth.)

Among all this detritus the gulls used to gather, picking over the spoils. At irregular intervals there came a distant rumbling in the pipe. At this the gulls’ excitement mounted, and with expectant cries of “kwarr” the flock drew closer to the broad mouth of the pipe, flying up when, with a rush, it disgorged a fresh supply of sludge.

During hard weather this was an important source of food for the gulls in the Colne Valley, and as many as 400 birds could be seen there at once. The dumping has finished now, but the sewage works still draw plenty of gulls. After detailed observation the same individuals can be recognized returning day after day, for some birds have peculiarities such as a deformity of the bill or an odd pattern of plumage. A few of the gulls carry aluminium leg-rings, put there by ornithologists perhaps in other countries.

One ring seen on a living bird bore the number C-17122 or C-1722. From this and a description of the pattern the British Trust for Ornithology were able to say that the ring was of Finnish origin, and in fact many of the black-headed gulls which winter with us breed in the countries round the Baltic Sea, especially Sweden and Denmark.

In Britain the black-headed gull breeds, especially in the north, on saltmarshes and sandhills close to the sea. Yet it is also the most inland of our gulls and nests on marshy islands in lakes and moorland pools far from the coast. In the early 1960s a few pairs even bred at Maple Cross, but the colony was soon abandoned.

It is difficult to imagine today that all gulls, even the black-headed, were once very rare in this area, being seen only when storms at the seaside blew them off course. Their success is attributable directly to man: they have learned to exploit the many opportunities, like the sewage outfall pipe, we have unwittingly put in their way.

The only problem for gulls inland is the need of a safe roost. The first gulls to appear in any numbers in London arrived in the bitterly cold winter of 1894-5, and they roosted then mainly on the Thames at Chiswick Eyot, or at the small Lonsdale Road Reservoirs.

At the turn of the century there was a big increase in reservoir-construction. The huge Staines Reservoir was completed in 1902 and quickly became a major gull roost. The other reservoirs in that part of Middlesex and north Surrey, some even bigger than Staines Reservoir, as well as a chain of reservoirs in the Lea Valley, provided further roosting. Today well in excess of 100,000 gulls roost in the London Area during winter.

When it was filled, in 1955, Hilfield Park Reservoir near Aldenham soon became an important roost, attracting something like 5,000 birds. Many of our local gulls roost there, and at dusk make their flight-lines in that direction. The rest of our birds roost, or did roost, at Staines, and the birds from the Colne Valley can be seen flying south at the end of day. This is where the Maple Cross birds roosted, arriving there 25 minutes after first light, having taken that time to fly, at 40 m.p.h., the distance from Staines.

But now these opportunists have found a way to cut their commuting time. A vast gravel pit, Broadwater, has been dug at Denham, large enough to make a safe roost, and many Staines-bound gulls have adopted it as their own.

A gull roost as it fills is an extraordinary sight. The sheer spectacle of so many birds in one place is not soon forgotten. To see them arriving, each with a different experience of the day’s foraging, is a powerful reminder of the adaptability of living things and the effect that man has had on their world.

As the gulls come in, you tend to forget about their feeding habits and are conscious only of a sense of wonder and beauty. If only all our activities produced a result like that.

(Introduction to these pieces; see all)

The Moon

Reflected Moon on Paddy-fields in Sarashina

by Hiroshige Utagawa

The full moon of August will be with us tomorrow. In one ceremony of ancient Japan this moon, seen reflected in water, symbolized more than anything else the mystery and transience of life. But to see the Moon at any time, and at any phase, can be an awe-inspiring experience. Whether you are in the comfortable north-western suburbs of London or camped out on an Antarctic ice-floe, the Moon presents the same inscrutable visage.

It is a true wilderness, remote, aloof from our concerns, and, except for the assorted junk left behind by space programmes, as yet unbefouled.

The familiar pattern on the Moon (representing a man’s face, a hare, a beetle, the Madonna and Child, or a dozen others, depending on your culture) is made up of the darkness of plains contrasted with the brightness of mountains. Seen with binoculars, the pattern disappears at once, and it is only then, with the Moon filling your field of view, that you get some idea of its majesty and size.

For, although the Moon is held to be a mere satellite of the Earth, it is much bigger than the moons of Mars or Jupiter, being over 1/5th the weight of the planet Mercury. Indeed, according to one theory of the Moon’s origin, it was once a small planet, with an independent orbit.

This theory suggests that, at some time at least four billion years ago, the Moon passed sufficiently close to the Earth to be “captured” by the Earth’s gravitational field. As the Moon passed there would have been huge tides, miles high, in the Earth’s oceans. The energy to produce these tides was thus transferred from the Moon to the Earth, slowing the Moon down and preventing it from getting away.

There is a theoretical limit at which any satellite can remain intact, called the Roche limit, which, in the case of Earth, is about 3,700 miles from the planet surface. Once the Moon reached the Roche limit it began to break up, losing half its mass to the Earth, especially the heavier rocks containing iron. This material became the present continental land masses.

The remnants, now just outside the Roche limit, gradually reformed into a sphere and began to retreat, towards the Moon’s present mean distance of almost 240,000 miles from the Earth.

An older theory was that the Moon was originally torn from the substance of the Earth, leaving behind the scar which we now call the Pacific Ocean. Recent understanding of the way continents drift makes this idea seem less likely, as does the fact that rock samples brought back by the Apollo missions prove that the geology of the Moon is very different from that of the Earth.

All the planets in our solar system, and their satellites, were formed by clouds of gas from the Sun, but not all were formed at the same time or from the same cloud. Another theory of the Moon’s origin is that the Moon has always been in the Earth’s orbit, but was formed from a different cloud. Of the three theories, the first is perhaps the most favoured today. Since we do not yet even know in detail how the Earth was made, it may be premature to expect firmer knowledge just yet.

These are matters for the physicists and mathematicians to ponder. But it requires no special knowledge to look at the Moon, and if you have even an old pair of opera glasses you can follow in the tradition set by Galileo, who first turned a telescope on the Moon in 1610. Although he probably knew that no large expanses of water were to be found there, it was he who named the dark areas maria (seas) and the light ones terra (land).

These terms have survived to the present day, inappropriate as they are. We now know that the Moon’s surface is almost unbelievably harsh. When Neil Armstrong took that “giant step for mankind” on 21 July 1969, he stepped into a desert of black, basaltic dust and rock, baked during full sunlight to the temperature of boiling water and frozen during the lunar night to the temperature of liquid air.

On the Moon there are mountains higher than the Himalayas and craters up to 180 miles across and 2,600 feet deep. The atmosphere is extremely thin, for the Moon’s gravity is only 1/6th that of Earth. This means that there is almost nothing to protect the Moon from the impact of meteorites, the chunks of rock which, hurled out perhaps thousands of years before by some disintegrating star, travel on and on through empty space until they meet an obstruction. Most of those striking the Earth get burned up by friction with our thick atmosphere: not so on the Moon.

The surface of the Moon is buried to a depth of several feet in meteorite debris. Its entire surface is pockmarked with craters, from the microscopic to the gigantic. When the impact is especially great, splashes of moondust are thrown in all directions. These bright splashes are called “rays”, and, until disturbed by further impacts, may clearly be seen from Earth.

One of the most perfect craters, as yet virtually undamaged by subsequent impacts, is Tycho. This is in the southern hemisphere, at about the same latitude as New Zealand is on Earth. The 54-mile wide crater has a sharp central peak and walls which rise to 16,000 feet.

The splashes radiating from Tycho have spread out across almost the entire visible face of the Moon, one ray even being seen to cross the Sea of Serenity in the northern hemisphere. The best views of the Moon are usually to be had at other phases, when the slanting sunlight makes the surface stand out in sharp relief, but full moon is the time to see the rays of Tycho.

The full moon – and what better than the August one, traditionally the moon to be viewed – is also, perhaps, the most impressive and the most suitable way of reminding ourselves of the true value and scale of things.

(Introduction to these pieces; see all)

Spotted flycatchers

Image: Andrew Easton

A new little bird appeared yesterday morning at the corner of the road, perching on a telephone wire high above the pavement. It first attracted attention by its call – a characteristic wee tuc-tucc, wee tuc which, once heard and learned, is never forgotten.

The owner of this cry is just the sort of small brown bird to puzzle the beginner, with mousy plumage above, paler underparts and a few dark streaks on the breast. But its upright, watchful posture and, above all, its behaviour, confirmed the identification at once.

From its perch on the wire the bird made repeated swooping sallies at flying insects, swerving in mid air to return to the same spot. After a short rest it ventured forth again, returning this time to a bare twig in one of the trees that line the road here.

Gilbert White, in his letter to Thomas Pennant of 4 August 1767, says: “The stoparola of Ray (for which we have as yet no name in these parts) is called, in your Zoology, the fly-catcher. There is one circumstance characteristic of this bird, which seems to have escaped observation; and that is, it takes its stand on the top of some stake or post, from whence it springs forth on its prey, catching a fly in the air, and hardly ever touching the ground, but returning still to the same stand for many times together.”

The good curate of Farringdon, in Hampshire, was as precise in this as in all the observations contained in his Natural History of Selborne: the bird on the corner was indeed a fly-catcher: a spotted flycatcher, to be exact, the Muscicapa striata of our zoology.

It was still present this afternoon, although it had moved a few yards along the road. It is on its way to Africa for the winter and, as flycatchers do, has taken a sudden and unaccountable liking to this place.

The preference of the flycatcher for one location over another is something of an enigma. On the one hand the bird tolerates man, often building its nest close to a busy path; on the other it seems attracted by the tranquillity of an unfrequented garden or woodland clearing.

One pair which nested in a small copse adjoining the school swimming bath were, with their fledglings, much in evidence when no one was about, perching now on the close-boarded fence by the grass, now on the diamond-mesh fence running from the changing shed to the filter house. The sound of the filters, the smooth surface of the deserted pool, the blue reflections and refractions, the dense foliage of the oaks and lindens of the copse: all this gave the place an air of magical seclusion of which the flycatchers seemed to form a natural part.

They were brought here by the many insects attracted to the water. Even when the flycatchers’ domain was invaded by a solitary swimmer they continued to feed. But as soon as more people arrived, the birds withdrew, emerging again only later when peace resumed.

Flycatchers are like this in gardens too. Best of all is a garden untenanted, overgrown, with plenty of neglected corners to bring the insects and a sufficiency of bare twigs for feeding-perches. Next best is a garden frequented, if at all, only by one or two gentle souls with trugs and secateurs. The passage flycatchers appear at hedge-clipping time. They do not object to the click of hand-shears, but vanish at the whine and rattle of electric cutters, or at the noise of all the other mechanical abominations with which even the smallest garden now abounds.

Yet the spotted flycatcher is one of the few species – the others are the chaffinch, great and blue tits, song thrush, blackbird, dunnock, and wren – that can thrive in the gardens of Inner London. They are able to do this because their requirements for food and nest-sites are comparatively unaffected by lack of undergrowth. Flies may be found almost everywhere, and their catchers are content to nest on a beam or branch close to a wall or tree trunk, or in a crevice in masonry. Thus flycatchers are among the few species able to breed in the Royal Parks or in the squares of Mayfair or Bloomsbury.

There is another sort of breeding British flycatcher, the pied flycatcher, with a more westerly distribution. This bird has been seen in the district only on a handful of occasions, usually on autumn passage. The spotted and the pied are typical of the flycatchers found in Europe, with flat, rather broad bills surrounded by bristles which help direct the prey into the gape.

Elsewhere in the world, especially in the tropics, there is a large and diverse array of birds of the flycatcher tribe. Some are brilliantly coloured, as small as wrens or as large as thrushes; many have habits nothing like those of our own native species. In New Guinea, for example, many of the fifty or so breeding species behave more like warblers, chats, or even shrikes than flycatchers. In Madagascar live species which live sociably in the tree canopy, just like our native blue tits and great tits. In south-east Asia are flycatchers which keep to the shadows of the undergrowth, like our robin.

But they all share a certain special elegance and grace, and give a peculiar impression of rightness in their habits and form. The flycatcher on the corner, by choosing this place for his halt on the journey south, has, in his own small way, conferred on it the accolade of his approval and made it better than it was before.

Probably he will be there tomorrow too, but the following day he may well be gone, leaving behind a sense of flatness, emptiness, and loss: a sense of impending autumn.

(Introduction to these pieces; see all)

Dragonflies

Anax imperator

Image: Agnieszka Urbaniak

The dragonfly is the heraldic emblem of these August afternoons. It is a creature of the heat, its darting activity and purposefulness a direct contrast to the lethargy that overtakes the canal, the river, the weed-choked ponds and streams. Its colouring belongs more to the tropics than to the English lowlands; and in its ferocity the dragonfly reminds us of the merciless insect-war going on, mostly unseen, everywhere in the dense vegetation of summer at its height.

Throughout the whole animal kingdom, indeed, there are no more brilliant colours than those of certain dragonflies. Insect colours are produced in various ways and for various reasons. Some pigments are mere by-products of other bodily processes, with no special significance, but most have some function, however obscure.

The bright yellow laid down in the cuticle of, say, wasps or bees, gives notice that the animal is not to be trifled with. Reds and oranges often signify that the owner is unpleasant to eat. Many other colours and patterns are important in camouflage, courtship, mating, or the defence of territory.

In some insects, colours are produced by intricate structural effects as well as by simple pigments. Iridescence in the more dazzling hues of many butterflies, and the metallic bronzes and greens of beetles, for example, results from an interference effect – involving the reflection of certain wavelengths of light from successive layers in the insect’s scales or cuticle. These colours are brilliant enough, but the dragonflies have gone one stage further.

Besides having a wide complement of pigments, they make use of a phenomenon called Tyndall scattering. In this, light is dispersed in all directions by irregularities in the cuticle surface or by granules laid down just beneath it. The size of the irregularities or granules is minutely adjusted to the wavelength of the light which is to be reflected.

Tyndall scattering is responsible for the incandescent blues and greens of many of our dragonflies. It depends for its success on a dark masking layer below the granules, provided by a brown-violet pigment, an ommochrome.

Ommochromes are widespread in insects. As well as providing brown, red, and yellow body-colours, they have a more specialized use as masking pigments in vision, isolating the individual elements of the compound eyes and enabling them to function.

This leads us to another remarkable feature of the dragonfly’s life, the refinement of its eyesight. Dragonflies are normally day-flying insects. They rely almost entirely on their eyes: the antennae, the seat of taste and smell, are poorly developed. In some insects the compound eyes may contain only a few widely spaced elements; in the dragonfly there may be ten thousand or more in each eye, closely packed together in a hexagonal formation.

Each element in the compound eye sends a signal to the brain, forming a sort of mosaic image. Compared with the human eye, focusing ability and acuity are not very impressive, but the dragonfly’s eye is supremely well adapted to detecting movement. There is very rapid recovery of bleached visual pigments, a high so-called “flicker rate”, enabling the animal to make sense of the landscape as it races past, and enabling it to see and catch its prey with lightning speed.

The prey consists mainly of flying insects, sometimes other dragonflies. It is caught with either the jaws or legs. The legs are found well forward on the thorax, which is itself tilted in such a way that they form a basket to scoop an insect from the air and hold it steady while the mouthparts are brought into action.

There are two sub-orders of dragonflies. The first contains the damsel-flies, and the second the larger, more powerful dragonflies such as the fearsomely named Anax imperator. The eyes in this second group reach an astounding peak of size and development, covering most of the surface of the head.

Much time is expended by the insect in cleaning the eyes with special movements of the forelegs. The head is balanced on a delicate suspension mechanism which allows it to swivel, giving all round vision. So delicate is this mechanism that if the dragonfly hits head-on even a lightweight obstruction – such as the folds of a collector’s net – irreparable damage will be done.

Set beside the technical achievement of constructing just one dragonfly, human efforts to date in the fields of cybernetics and microelectronics look distinctly clumsy. To be fair, the craft of dragonfly-making has had some three hundred million years in which to be perfected: the dragonflies were among the first of the insects to evolve.

The individual adult dragonfly also has a long time in which to develop. Most of a dragonfly’s life is spent underwater, as a nymph, a fierce carnivore which repeatedly moults its skin as it grows in size. There may be a dozen moults in all, and the underwater period varies from one year in the damselflies to a dozen in the largest species. When the time comes for the final moult – usually in June or July – the nymph crawls up a plant-stem, often during the early hours, and, with frequent pauses for rest, breaks out of first one part of the skin and then another.

By dawn the newly emerged, or teneral, dragonfly resembles a mature adult in all respects except for its pale colouring and the flaccidity of its wings and body. As the sun rises the wings harden and become ready for flight. The cuticle hardens also, and within a few hours the insect is ready to fly: the colours develop over a period of days.

In the few weeks of life remaining to it the dragonfly must mate. Females are actively sought out by the males, which frequently are strongly territorial, maintaining one stretch of water as their exclusive property. The eggs are laid in vegetation, or simply scattered in the water to sink to the bottom.

With the first frosts the remaining adults are ruthlessly cut down. Together with hundreds of millions of other insects, they have betrayed themselves by leaving eggs to perpetuate the race. They are no longer required. Thus does Nature treat the most intricate fruits of its creation: and thus vanishes the magical dragonfly, emblem of this brief English summer.

(Introduction to these pieces; see all)

Balsams

Small Balsam

Image: André Karwath

Much is achieved by specialization in the study of natural history, but a more open and discursive approach is often more enjoyable and can lead to some unexpected byways, and, finally, to a deeper understanding of the subject as a whole. For one feature of the living world always holds pointers to another, and another, and so on, a chain of fascination and discovery without end.

The first link in the chain is usually forged lightly enough, with an idle speculation. On a walk through Cassiobury Park, for example, an unusual, weedy-looking plant may be found at this time of year. It grows abundantly in the gloomy woodland near the canal and River Gade in the southern end of the park, especially by the paths in the vicinity of the commercial watercress-beds.

With small yellow flowers and large, toothed leaves rather like those of the Dog’s Mercury, this plant is the Small Balsam, a close relative of the Busy Lizzie which makes such an easy and attractive pot-plant. It is a native of Siberia and Turkestan, and was introduced to this country in the last century, having first been found growing wild here at Battersea in 1851.

In Hertfordshire it occurs mainly in the vicinity of certain towns, including Hemel Hempstead and Watford. Its distribution in the county can be understood when it is known that one of its favourite habitats is timber yards and that seeds were presumably imported in the 19th century as stowaways in consignments of exotic timber from the east. The presence of Small Balsam in the Gade Valley may not be unconnected with the Corner Hall Wharf at Hemel Hempstead of W. H. Lavers & Sons, the well known local timber merchants.

Having been inadvertently introduced, the Small Balsam spread out as far as it could, being checked only by its own needs for moisture and shade. Most balsams are a bit like this, never being found far from water or damp ground. The Busy Lizzie likewise needs plenty of water to keep healthy.

A second alien balsam, the Orange Balsam or Jewel-weed, is also found in Cassiobury Park, as well as elsewhere along the line of the Grand Union Canal. In fact, a map of its distribution in Hertfordshire is tantamount to a map of the course of the canal. A larger, more handsome plant, with orange flowers spotted with crimson, the Jewel-weed got here from eastern North America as a garden introduction, first turning up in the wild in Surrey in 1822. It is now locally common along most of the waterways of the Thames basin and is apparently still on the increase.

Yet a third alien balsam, the Himalyan Balsam, variously known as “Policeman’s Helmet” (from the shape of the flowers), “Jumping Jack” (from its explosive seed dispersal mechanism), or “Nuns” (for no discernible reason!) can be found in the park. A big clump grows beside the third bridge over the Gade (counting downstream), adjoining the most luxuriant growth of the Small Balsam.

Policeman’s Helmet is an even showier plant than the Jewel-weed. It can reach a height of six feet or so, has thick and often reddish stems, and large flowers in every shade of purplish-pink. Again it was introduced in the 19th century as a garden plant, a native of India and the Himalaya, and was cultivated at first as a greenhouse annual. It soon escaped from captivity and by 1855 was to be found spreading rapidly along waterways.

Now these three foreign balsams illustrate a number of the laws by which nature seems to govern her affairs. The vigour with which they have taken over our waterways shows how alien genetic stock, freed from the competition at home, can have an unfair advantage over the home-grown organisms – for it is the same with fauna as with flora. The native stock has not had time to evolve defences against them: the checks and balances built up over tens of thousands of years no longer have any meaning.

The only native balsam, the Touch-me-not, is, in plant terms, something of a failure. It puts forth its flowers in damp woods in north-west England and north Wales, being very local even where it is found. It cannot compete effectively. Man’s mistreatment of the environment is going hard with it, while its foreign cousins are actually taking advantage of man and his activities.

The four British balsams, one native and three introduced, are all closely related and are obviously descended quite recently from a common ancestor. In size, though, they show a clear differentiation. Each species occupies a slightly different niche, has a slightly different role to play: this is how new species evolve. They rarely trespass on each other’s terrain. The Small Balsam, for example, is pollinated by hoverflies, the Touch-me-not by bees, and the Policeman’s Helmet by bumblebees. As for the Jewel-weed, it may dispense with pollination altogether, its flowers often all being of a type known as “cleistogamous”.

Cleistogamy (literally, “closed marriage”) is an unusual and somewhat degenerate response to the heavy cost of producing flowers as a means of reproduction. Cleistogamous flowers are of simplified form, with few pollen grains, and automatically self-pollinate at the bud stage. Among our group of balsams there is a pretty smooth gradation in this habit, from the Policeman’s Helmet, in which it is unknown, through the Small Balsam and Touch-me-not, in which increasing numbers of cleistogamous flowers are found, to the Jewel-weed, in which cleistogamy has assumed major importance.

A study of cleistogamy in these four plants would lead us deeper and deeper into the realms of genetics and evolution. A study of their habitat preferences draws us into the fields of plant physiology, ecology, and climatology. A study of their origins takes us to the history of human trade and commerce, 19th century tastes in timber and veneer, the exploitation of Russian and Asian forests to meet those demands ...

And so it goes. Many, if not all, the scientific investigations ever undertaken have had just such trivial beginnings as a stroll through the local park and an idle question like: “What’s the name of that plant?”

(Introduction to these pieces; see all)

Lichens

Image: Ericd

The tenacity of living things sometimes surpasses belief. There is scarcely a square mile of the planet surface, no matter how forbidding, which does not support at least some form of life. The richness and diversity of living systems reach their astounding zenith in the tropical rain forests; their nadir is at the polar icecaps, especially that of the south.

Even in the polar wildernesses of rock and scree, and even, in places, in the ice itself, life may be yet found. The forms here are usually quite simple, single-celled animals and plants. Where conditions relent slightly, if only for an hour or two a day at midsummer, the terrain is colonized by lichens.

In fact, over great tracts of the world’s most inhospitable regions, lichens are the only multicellular organisms able to thrive. They grow abundantly in such daunting places as rocks which are alternately washed by the sea and baked by the sun. They will grow on walls, roofs, tree-trunks, on the bare soil. Some sorts even secrete acids which enable them to grow inside rocks, waiting for the surface to weather away before fruiting.

The key to their success is as strange as it is wonderful, and may be studied here in suburban Hertfordshire as well as in Antarctica or the Sahara desert.

Though given a single scientific name, a lichen is really a partnership of two separate sorts of organisms – a fungus and an alga. Fungi do not have chlorophyll, and so cannot use photosynthesis to manufacture their own food, as green plants (including the algae) do. On the other hand, most algae cannot, unaided, survive extreme conditions. By entering into partnership, the fungus receives sugars and vitamins from the alga, while the alga in turn gets minerals and protection from extremes of dryness and illumination; and both organisms are then enabled to colonize places previously out of bounds.

A handful of the familiar mushroom-type fungi undergo lichenization, as the process is called, but the vast majority belong to a more primitive group, the Ascomycetes.

So specialized have these lichen-fungi become that few are now able to survive for long without an algal partner. The algae, however, especially if conditions are favourable, can often exist independently. Free algae of the right sort must be available for the formation of a new lichen by sexual reproduction, for it is the fungal element alone which produces spores. The fungus is the senior partner, makes up the bulk of the lichen’s structure, and gives the lichen-plant or thallus its characteristic shape; the thallus usually has one of three main types of form: shrubby, leafy, or crust-shaped.

The clustered thalli can appear quite fantastic, like creatures from another world, or the vegetation dreamed up by an artistic imagination on the verge of madness, and the colours, which are always marvellously subtle and soft, come from Nature’s most ethereal paintbox. At different seasons and in different states of dryness the appearance may change dramatically, for during adverse conditions the lichen “shuts down” and waits for things to get better.

Unless conditions are exceptionally favourable, most reproduction is by vegetative, or non-sexual, means. Many sorts produce little powder-dusted pores which also help to keep the thallus aerated; the particles of powder are called soredia, each of which, when dispersed by the wind or by sticking to animals and birds, can grow into a new thallus. Even simpler and more common is dispersal by fragmentation: bits of the parent thallus get broken off, for example by being trampled, and blow away to develop elsewhere.

The pores in a lichen ensure that there is free flow of gases between the photosynthesizing algae and the outside world. Lichens are often efficient at absorbing whatever substances are in the environment, which has had dire consequences for those Lapps and Eskimoes who depend on caribou and reindeer for food.

One of the main components of the vegetation of the northern tundra is the Reindeer Moss, which, despite its name, is a lichen. It bulks large in the diet of the reindeer and caribou, and is the main source of carbohydrate in that particular food chain. Unfortunately, Reindeer Moss is exceptionally good at absorbing the radioactive fallout from atom-bomb tests which finds its way into the upper atmosphere and is then distributed all over the planet surface. High levels of radioactive caesium and strontium have accumulated in the bodies of the grazing animals, becoming even more concentrated in the bodies of the northern people.

So good are lichens at absorbing toxic substances that they have been used as indicators of atmospheric pollution. The lichen flora of, say, North Devon or rural Scotland is rich in species: 1400 in all have been recorded in the British Isles. But as you approach the industrial centres the number of species falls off rapidly, as does the luxuriance of growth of those that remain.

Our local lichen flora is badly impoverished, simply because the air here is so dirty. The main pollutant is sulphur dioxide, produced by the inefficient burning of fossil fuels. But others, in far smaller quantities, and even more dangerous, are contributing to the continuing decline in lichens: fluorides, heavy metals such as cadmium and lead, agricultural and garden fertilizers and pesticides, and a whole catalogue of other industrial wastes – the list is depressingly long.

Lichens may be regarded like the coal-miner’s canary. We ignore their death at our peril. The few species that remain to us in south-west Hertfordshire survive mainly by growing on alkaline surfaces, such as walls, asbestos roofs, limestone paving, and concrete, which offset to some extent the acidity of the rain.

Yet the ability of the lichens to colonize inhospitable terrain is undiminished. By poisoning the atmosphere, we have altered the balances that have remained unchanged for millennia, and those types which have become adapted to them will die. But already there are new and – almost – sinister types of lichen emerging, able to thrive in the new conditions. One, the aptly named Pollution Lichen, was unknown in Europe before 1860. A recently published guide chillingly gives its status thus: Widespread in industrial and densely populated parts of Europe. Abundant in England.

The writing, plainly printed in lichen thalli for anyone to see, is on the wall.

(Introduction to these pieces; see all)

Preening

Image: Hariadhi

The old stone bird-bath is much weathered now, cracked by past frosts, and in places its square, layered pedestal has become encrusted with grey and yellow lichen. It stands at a point in the garden a fair distance from the house, in the middle of a quartet of rose-beds virtually surrounded by yew hedges. On three sides there are trees of varying sorts and ages, some quite large.

Human disturbance is minimal; there is no dog in the household, and the only cats are occasional and unwelcome visitors from neighbouring gardens, so the place is a haven for birds. Kept topped up daily with the watering-can, a bird-bath provides a focal point for the garden and an endless source of movement and interest.

The most compulsive bathers are starlings, which create a tremendous amount of spray as they attack the water with their wings. Just now, in mid July, the greyish-brown juvenile starlings are especially numerous, and crowds of them are all trying to get into the water at once, leaving the less pushy dunnocks and song thrushes waiting on the grass nearby.

From time to time, when the starlings permit, almost all the birds in the garden will come down to drink or bathe, and this is often the best chance to get a view of shy or otherwise hard-to-see species. This afternoon a blackcap has been down, as well as a willow warbler and, earlier, a great spotted woodpecker.

They expose themselves to view because they must. Bathing for these birds is essential to maintaining the plumage in good order. Its function is not primarily one of cleansing, but of preparing the feathers for what comes next. Indeed, most birds are careful to avoid getting their plumage drenched, because this eventually renders the feathers brittle and, more importantly, robs the bird of its power of flight.

The water-bath is a carefully controlled wetting, spreading an even layer of moisture over the feather surfaces. Having repeatedly ducked its head into the water and flicked spray over its back, the bird performs special shaking movements to rid itself of surplus water. The exact pattern of these movements varies from group to group; some birds, such as gulls, can shake their feathers even while flying.

A bird like the blue tit is typical of the garden bathers. Immediately it has finished at the water, it retires to a less exposed position in order to preen in safety.

The great majority of birds have a special gland just above the root of the tail. The gland secretes oil which keeps the feathers supple and waterproof. Preen oil has another function too. Birds, like humans, cannot synthesize vitamin D inside their bodies. We manufacture it in our skin, provided we are exposed to the sun. Vitamin D synthesis likewise takes place in the oil; the vitamin is then either absorbed through the skin or ingested by the bird while preening.

The first act of preening is to stimulate the oil gland with the bill; oil is then quickly transferred to the plumage with quivering and stroking movements. The bird must work fairly rapidly because the oil hardens on exposure to air. The fact that the feathers are damp delays the hardening and enables the oil to be spread more evenly.

Having made a quick distribution of the oil, our blue tit, as soon as it has the opportunity, moves on to the next, longer and more leisurely, phase of preening. The outer feathers are ruffled up, to make them easier to get at, and each area receives its share of meticulous attention. A bird’s plumage is one of its most important assets, and much time each day is devoted to its care, both in these special sessions and during any odd moment.

There are two main types of preening movement. With the bill closed the bird sleeks down disarranged feathers and flicks away foreign particles. With it open, individual feathers – especially those of the wings and tail – are lightly combed.

The structure of a feather is a miracle of design. A large flight feather consists of a central shaft fringed on each side with about a hundred filaments, each of which, in turn, is fringed with smaller filaments or barbules. Each barbule has several hundred minute hooks which interlock with neighbouring barbules; there may be a million such hooks in a single feather. The combing action helps to restore the interlocking pattern and produce once more a smooth and continuous vane for flight.

Besides preening, birds in the garden may be seen maintaining their feathers in other ways. A favourite pursuit, especially of thrushes and blackbirds, is sunning. The bird, feathers ruffled and wings drooped, squats with its back to the sun, apparently just enjoying the heat: but the light helps to disturb parasites among the feathers, and makes them come out into the open where the bird can preen them away. A more extreme sunning posture has the bird sprawled with one wing fanned out towards the sun, its body tilted sideways and the tail swung round to the same side.

Dust-bathing is also indulged in by some birds, including sparrows and wrens. Its purpose is not clear, but may also have something to do with discouraging skin parasites. The same is true of the strangest feather-maintenance practice of all, anting.

In this the bird puts ants among its feathers, or simply squats over an ants’ nest, allowing the ants to crawl into its plumage. It is thought that the exudations of the ants, like preen oil, help to keep the feathers in good condition. The type of ant usually chosen secretes formic acid when it is angry, which certainly acts as an insecticide, and the ants themselves may attack any parasites they come across. Hundreds of species of perching birds have been observed anting, but starlings, crows, and especially jays, are particularly addicted to it.

In fact there are starlings on the lawn at this moment, taking ants from a nest halfway down the path.

This is the kind of ornithology anyone can study, whether from a window or a deckchair. All you need is a sharp pair of eyes – and a bird-bath. It need not be elaborate; an old dustbin lid will do, as long as it provides a shallow gradient and its site a measure of seclusion.

(Introduction to these pieces; see all)

Nettles

Image: Jerome Prohaska

Near the abandoned watercress beds, within a few yards of the stream, the ruins of an old cottage adjoin the footpath. The rubble is overgrown with stinging nettles, which protect the precincts of the cottage from intrusion.

By the middle of July the nettles have reached their greatest height. They grow here so well because the soil is rich in nitrogen – bequeathed by the middens and latrines of the former occupants. The plants are getting old and tough now, and even more uncompromising than they were in the spring. A bed of “stingers” is agony to walk through with bare legs and arms, and usually receives a punitory slashing from the countryman’s stick.

Is this punishment deserved? The nettle, after all, is only protecting its own, and uses the same irritant, formic acid, that is found in ants’ stings. Both weapons have the same purpose – to repel invaders.

The nettle’s stinging organ is simple but effective, a modified hair, long and hollow and with a swollen base into which the acid is secreted. The point of the sting is formed by a very sharp, very thin scale of silica (the basic ingredient of sand or glass). The scale is so sharp that even the slightest contact causes it to break off in the skin, making a tiny wound, and the acid is then squirted into the wound by contraction of the base, rather as in a hypodermic syringe.

If the plant is wilting, dried, or cooked, the mechanism will not work; and if you “grasp the nettle” you will not be so much stung, for many of the hairs will be bent or crushed before they have a chance to act.

The sting was probably evolved as protection from the browsing lips and tongues of deer and wild cattle, for the nettle was originally a plant of lightly shaded woodland and clearings. It is dioecious (having “two houses”), which means that the straggly catkins of male and female flowers are found on separate plants. The male flower has four stamens, each bearing a pollen-laden anther at its tip. The stamens are sharply bent inwards to the centre of the flower, being released like catapults to send their pollen dust drifting on the wind.

The flowers are rather reminiscent of those of the cannabis plant, and inside a big nettle bed, especially after a long spell of dry weather, the smell is distinctly redolent of the forbidden weed – which is not to be wondered at, because the two plants belong to closely related families.

Like cannabis, which provides the hemp fibres used still in making rope, the nettle also yields fibres which can be woven; at one time in Europe, especially in Scandinavia, nettles were widely used for this purpose. Fragments of nettle cloth have been found in a Bronze Age grave in Denmark, and cloth was produced commercially in Silesia as late as 1920. Indeed the Germans, during World War I, turned to the nettle when their cotton supply was cut off, and used it for making military clothing. Over two thousand tons of fresh plants were taken from the wild, although it needed nearly ninety pounds to make just one shirt!

Nettle makes an unexpectedly good fabric, strong and light and fine, and a nineteenth century Scottish poet, Thomas Campbell, writes of sleeping in nettle sheets and dining from a nettle tablecloth. The stalks are picked in late summer, dried, stacked, and then wetted so that they begin to rot. Next they are dried again, and beaten to remove the rotten tissue from the fibres. The fibres can then be spun into thread, like flax or cotton (though nettle fibres are not so long), and woven in the ordinary way.

The commercial growing of nettles in England in medieval times is perhaps echoed in such place-names as Nettlebed (near Henley-on-Thames) or Nettleden, near Hemel Hempstead.

Besides the cloth, nettles will make the dye, provided it is fixed with the right mordant, alum. Admittedly the colour is rather a dull green, but it was this very quality that led to our use of nettles in the Second World War. We used hundreds of tons of them for dyeing camouflage nets.

They also provided a ready source of chlorophyll. The nettle is rich besides in calcium, potassium, iron, sulphur, and vitamins A and C. The young shoots, which do not sting, can be eaten in spring as a salad or cooked like spinach and served with butter and pepper. When dried, they make a herbal tea. A year or two ago I experimented with some wild herbal teas, and although most were pretty disgusting, the nettle tea I could at least drink more than once. It had a delicate aroma and was curiously warming, like a glass of brandy. When added in small quantity to an Oriental tea, the nettle imparts a most unusual and exotic flavour which is well worth sampling.

Nettles figure in a number of herbal beauty formulae. An infusion of young or dried leaves is supposed to make a very good skin toner and an astrigent bath additive.

It is as a medicinal herb, though, that the nettle really comes into its own, and has been used, with greater or lesser success, in recipes to treat a wide range of maladies, including bronchitis, whooping cough, pleurisy, and other chest complaints; diabetes, dropsy, gout, rheumatism, varicose veins, menstrual problems, diarrhoea, constipation (yes, both!), stomach ulcers, and piles.

Some of these cures are undoubtedly effective in some cases, and the nettle was a highly prized addition to the pharmacopoeia in former times.

In return for all this bounty, our ancestors were able to forgive the nettle its sting. Next time we pass this ruined cottage by the stream and feel like wielding the big stick, perhaps we should do the same.

(Introduction to these pieces; see all)