CHAPTER TWO

Birds of Prey

Birds of prey are familiar to many of us as those imposing, regal and – for some – cruel creatures of the air, which prey upon land vertebrates for food. In the public imagination, species such as eagles loom large; symbols of wilderness and power. To others, birds of prey are simply a menace, a threat and a presence to be discouraged or, at least, despaired of, as they purportedly hunt down and destroy entire populations of smaller birds. In fact, whether seen as apex predators, or villains with talons, birds of prey are much misunderstood. One reason for this lies in the long history of ecocide that has taken place in our country.

Britain has for so long broken its contract with the natural world, and destroyed so much, so widely and for so long, that we have all forgotten the true numbers and diversity of birds of prey that would once have hunted our island – and the roles that they once played in enhancing the natural world around us. And even now, with many birds of prey recovering from the brink, we still enjoy these birds as a mere vestigial presence; museum relics of their former numbers.

If restored fully across the United Kingdom, our replete assemblage of birds of prey would have effects as surprising as they are profound upon the natural world. In fact, an abundance of avian predators within an ecosystem acts not only to regulate but also to enhance the lives of many other creatures, surprising as this may seem. And to investigate this further, we might begin not with the life history of one familiar bird of prey, the sparrowhawk – but the story of the bullfinch.

In the 1950s, bullfinches were everywhere. They were hedgerow birds, orchard birds, field birds – and middle-of-the-field birds. Not only were bullfinches blazing in the hawthorns and the brambles, amid the hips and the haws, but they lit up Britain’s crops. Fruit growers were at their wits’ end as airborne shoals of secateurs sliced through their profits. Wherever the bullfinch went, fruit buds vanished: nibbled to oblivion by precise black bills. And so perished whole crops of apples and cherries.

Bullfinches are ecologically designed to raid fruit trees. Fruit trees are evolved to put out enough fruit to weather this assault. What fruit trees are not evolved to cope with, however, is a world where the bullfinch is in charge. And so, for some years from the late 1950s until the 1970s, Britain’s fruit trees – invaluable sources of life for farmers, cider makers and many wild birds – became imperilled organisms, bereft of natural defence. It seemed that nothing could be done. Yet within two decades, the bullfinch onslaught would be driven into retreat.

The answer would come in the form of a low, silent ambush. A swivelling bullet, slicing the hedgerow edge; piercing the open gap. A projectile guided from the front, steered from the back, the weaponry loaded underneath. At the end of the 1970s, the sparrowhawk came back, as its population slowly recovered from secondary poisoning by the since-banned pesticide, DDT. And as it did, the bullfinch’s playing field was changed forever.

The true power of sparrowhawks does not lie in how many birds they kill, but in the decisions they force other birds to make. Just as a line of shops near a dangerous part of some of the world’s cities may empty of custom through the mere reputation of its neighbours, so whole areas of habitat become shunned as soon as a sparrowhawk reappears on the scene. The landscape of fear is created as soon as one plump, unwary bullfinch, fattened on fruits and light on vigilance, is plucked in front of its field-dwelling peers. House sparrows, the hawk’s eponymous prey, favour areas with dense cover to dive into, beyond the reach of diving, grasping talons. In one study, it was found that redshanks tended to avoid certain areas of prime wet meadow as soon as sparrowhawks moved in. So fear-inducing is the long-tailed missile of the sparrowhawk’s shape that other birds have copied it for effect. The female cuckoo, flushing grassland birds as she wickers from her low bushy perch, resembles a sparrowhawk. Panicked, pipits, dunnocks and warblers depart their nests, exposing the eggs to the cuckoo, among which she will, furtively, sneak one egg of her own. In short, sparrowhawks decide who feeds where.

The sparrowhawk begins nesting quite late in the spring – in the middle of May. Throughout a tense month, the male, who can occasionally be killed by the larger female, zealously brings his mate proteinous parcels of sparrows, tits, finches and other small birds. In the middle of June, the sparrowhawk’s chicks hatch. The female, at this point, rises tenderly on muscled haunches, standing far enough above the chicks to allow them to breathe, yet shielding their sparsely downy bodies from the light of the sun. For the next few days, as the chicks’ downy feathers sprout and flower, she will tend them closely. Then, with the chicks able to be left by themselves, all manner of chaos is brought to the woodland around, as both parents begin shopping in earnest.

A month earlier, birds such as blue and great tits have timed the hatching of their own chicks to coincide with the abundance of insects, especially aphids and caterpillars, found in the unfurling leaves of the oak. And now, young sparrowhawks hatch into the world ready to dine upon a veritable feast of dim, unwary and newly fledged insect-eating birds. Yet these apparently defenceless birds have prepared for the onslaught ahead. By laying between eight and ten eggs each, sometimes as many as 14, birds like blue tits future-proof their families; providing nature with a surplus of witless chicks.

June is the month that decides whether sparrowhawk chicks live or die. Each day, up to a dozen small, de-feathered meatballs will be brought to a sparrowhawk’s nest. Brutal as the onslaught may seem to human eyes, these predators are merely harvesting the surplus. And in doing so, the role of the sparrowhawk, whilst not protective of the blue tit, becomes protective of the wider woodland environment in which it lives. But how?

Hunting aphids by the thousand, blue tits are the pest-removal service of our woodlands, ridding us of more plant parasites each year than all our gardeners combined. Yet aphids, too, play a fundamental role in the health of our woodlands. Removing too many aphids would have far-reaching consequences, most of all for our most industrious of engineers – the ants. And this is what would happen, if blue tits were left unchecked. In fact, the ramifications of blue tits having life all their own way could be profound.

Let’s take the southern wood ant – a crucial species in the diet of green woodpeckers. It will commonly climb 30 metres into old oaks, birches and pines, where it will begin a farming operation perfected over millions of years. Gently stroking an aphid’s abdomen, the wood ants elicit the production of sucrose-laden honeydew. Those aphids stroked by ants, it has been found, tend to produce smaller droplets of dew, richer in the amino acids that ant societies need to grow their young. In turn, the ants will zealously guard ‘their’ aphids from attack, spraying formic acid at any predator that dares to intrude. Then, their abdomens warped and bloated with rich sugars, the ants scale back down the furrowed bark, bringing honeydew to their queen and her workers, and regurgitating it to feed the brood. In doing so, species like the pine aphid fuel the formation of Britain’s most spectacular ant cities. And growing to a metre in height, wood ant nests provide a bounty of food for other birds. What’s more, wood ants also act as predators of defoliating insects, protecting our native trees from harm.

Ants, by moving soil and collecting insect food, alter the composition of our soils. Ant nests, in particular, have been found to dramatically improve the abundance and diversity of grassland plants, and insects, within the vicinity of a nest. Too many ants, however, reverse this effect. These powerful micro-predators, fuelled by aphids, are kept in check by the actions of aphid hunters such as blue tits. But for such nuanced societies to survive, the role of sparrowhawks in harvesting the aphids’ hunters is even more important.

Perhaps, given any thought, the destruction of a delicate treetop aphid farm by a blue tit is no lesser form of natural vandalism than the sparrowhawk plucking a blue tit on your garden lawn. Yet, in spite of their important role in protecting aphids, ants and grassland diversity, the role of the sparrowhawk is much misunderstood. Even now, pseudo-scientific charities in Britain have looked to the decimation of our insectivorous birds in recent decades – and picked a villain on whom to pin the blame. Ignoring food loss and the loss of large areas of sympathetic habitat, it has been easy to demonise the sparrowhawk.

Yet it is not in the nature of a sparrowhawk, nor in its fundamental interest, to wipe out the prey that it depends upon for survival. In the longest-running study of any bird of prey, the renowned professor Ian Newton found no evidence that sparrowhawks wiped out the animals beneath them on the trophic ladder. Rather, with sparrowhawks absent, rather than dying of predation in summer, prey populations such as blue tits were limited, instead, by a slower starvation across the winter months. By this time, however, the damage wrought by a surplus of blue tits upon insect communities would already have been done. In terms of ecosystem benefit, then, it is better for young birds to die in summer than to overburden our woodlands, and their resources, come the autumn.

In reality, the role of the sparrowhawk is far more remarkable and beneficial than the simple killing of small birds. Whether protecting aphid-reliant ant societies or fruit trees, sparrowhawks – both through the predations they carry out and the fear-factor they engender that changes the behavioural patterns of birds within their territory – act to protect and enhance the lives of both insect and plant communities. Yet, for all its yellow-eyed ferocity, the sparrowhawk, too, is designed to be served for dinner. In the ocean, it is said that there is always a bigger fish, and in the taloned world of birds of prey, the very same rule applies. In fact, the sparrowhawk is not, quite, where the food chain ends.

A female goshawk, bulging with a kilogram of muscle, five times the weight of a female sparrowhawk, is a formidable predator. For 10km² or more around her home, a host of smaller taloned creatures must hide, flee or die. Goshawks are the hunters both of adult birds of prey but also, more often, their young. They do so for food – and also to reduce competition. This rarely seen yet normal behaviour, known as ‘intraguild predation’, is one means by which smaller aerial predators are kept in check.

At the time when 60 per cent of Britain was covered in large tracts of Atlantic rainforest and vast wood pastures, it is thought that as many as 20,000 pairs of goshawks may have hunted our island home. Their dominant presence in all largely wooded areas would have ensured that sparrowhawks and kestrels, and even buzzards and kites, remained refugees in those of our landscapes – such as scrub grasslands or river valleys – less suitable for the goshawk’s needs.

Eradicated by the end of the nineteenth century, the goshawk’s loss has imbalanced the countryside for centuries. And whilst it has now returned in good numbers to Wales, western England, the New Forest and areas of Scotland, we still enjoy goshawks as prized rarities, rather than the dominant woodland predator of our wider countryside.

Goshawks require large tracts of woodland in which to hunt, though they hunt it with enormous flexibility. From the dark plantations of upland Wales to the broken deciduous woodlands of Herefordshire, and the ancient wood pastures of the New Forest, the goshawk thrives and kills in them all. Given a complete absence of persecution, as seen in Germany, for example, so adaptable is this woodland hawk that it can hunt as effectively in Berlin’s city parks as in the larches of the Forest of Dean.

Goshawks will rip kestrels from their nest without a second thought, and pummel young buzzards and honey-buzzards to death. Video footage has showed Polish goshawks calmly flying off with the large chicks of lesser spotted eagles. Recent nest-cam footage from the BBC’s Springwatch even showed a pair of goshawks pelting towards an osprey eyrie. As the larger osprey takes off to tackle one adult goshawk, the other deftly flies off with the osprey’s large chick, with barely a second’s delay.

Sparrowhawks are also high up on the taloned menu for goshawks, and frequently found, plucked, below goshawk nests. Young tawny owls, unwarily ‘branching’ from their tree-cavity nests, are transformed from downy to mere down. A host of other species, including grassland-nesting short-eared owls and copse-nesting long-eared owls, can be removed from the territory of goshawks, as was studied at some length, again by Professor Ian Newton.

In the 1980s, the goshawk returned to Northumberland’s Kielder Forest and to the Scottish Borders. A large area of dense spruce plantation intersected with rough, vole-wriggling moors, Kielder was home to a wide range of common birds of prey. Kestrels hunted small birds and rodents at its margins. Ground-nesting short-eared owls floated over its grasslands, seeking the field voles that constitute almost all of their diet. Buzzards, recovering well in most of their range as rabbit populations increased, were abundant. The goshawk’s arrival transformed the state of play.

At one goshawk nest in the Borders alone, 20 newly plucked kestrels were found at the end of summer. Just as sparrowhawks time the hatching of their young to coincide with an abundance of the young and unwary, so goshawk chicks demand the most protein during the time when young raptors of other species are also in the nest. As well as eradicating competition, the killing of smaller predators by goshawks feeds to their own chicks a prime steak’s worth of meat, the muscle richer and denser than that of a woodpigeon or squirrel. Within a decade, almost all kestrels, and most breeding short-eared owls, had vanished from Kielder Forest.

Whilst an onslaught like this may seem ferocious and destructive, such an apparent killing spree is generally what happens when a cornerstone predator, absent for decades if not centuries from much of the landscape, makes a sudden return. Just as the wolves in Yellowstone killed more than 20 elk per wolf pack member in the years after their reintroduction, and wiped out a large number of coyotes, so British goshawks have got to work in rebalancing our own long-imbalanced aerial food chain. But as they have done so, remorselessly ripping out the smaller predators, the beneficial effects have been profound and surprising.

Goshawks are not only the predators of other birds of prey. In addition to squirrels, woodpigeons and a range of larger prey (including ducks, and even birds as large as greylag geese), it is the predation of crows that renders goshawks so important to the countryside. Prior to the goshawks’ return to Kielder, huge marauding gangs of non-breeding carrion crows were wreaking havoc. Barely ever hunted by sparrowhawks, there is nothing more devastating to landscape diversity than an army of crows with time on their hands.

Carrion crows, as gamekeepers will correctly warn, are a threat to the life of wading birds. Sitting at leisure upon a tree, bush or telegraph post, crows will watch ground-nesting birds, like curlews and lapwings, as they return to their nests and will then make off with all the eggs, or as many newly hatched chicks as they can capture in the grass. In doing so, carrion crows, as well as magpies and ravens, can dramatically reduce wader breeding success.

The presence of goshawks changes such a dynamic. Indeed, on returning to a breeding territory, one of the first game-keeping services provided by goshawks is the removal of a large proportion of a landscape’s magpies. Clever at planning but terrible at flying, a magpie is no match for the aerial agility of a goshawk. Carrion crows are often next to go – since the goshawk’s return to Kielder, huge reductions have been seen in the crow population. Furthermore, jays (which raid the nests of many other species) must become ever more wary if they are to survive. In controlling the predators of nests, goshawks, which seldom bother with protein parcels as small as eggs or newborn chicks, can therefore increase the chances of survival for some of our most vulnerable birds.

In the rich woodlands of the New Forest, one of many birds thriving here, yet vanishing elsewhere, is the enigmatic hawfinch. A powerful parrot-like finch whose black eye-mask gives it a perennially angry expression, the hawfinch has a seed-crushing bill that can slice through cherry kernels or, in the case of one unfortunate bird ringer, the bones of a human finger. Hawfinches are canaries in the mine when it comes to the health of a woodland. Not only do they need large tracts of deciduous woodland to survive, but they also favour the oldest and most diverse of woods. Oaks provide them with moth caterpillars to feed their chicks; hornbeam and beech provide them with fallen mast in the autumn months; and crab-apples and cherries, rare in many newer planted woodlands, can be vital sources of food come the winter. In the past three decades, hawfinches have vanished from most of our woodlands, including almost all of the smaller ones. This has happened for a number of reasons, including the loss of wood-pasture habitats and older deciduous trees within the landscape, the loss of a rich diversity of trees from many habitats – and also, nest predation.

Hawfinches now persist, in good populations, in just five areas of Britain, and in many of these they continue to prosper. From the woods of the southern Lake District to north-west Wales, the Forest of Dean and Wye, and the New Forest, the hawfinch’s last strongholds share two things in common – large tracts of mature deciduous trees, and, more surprisingly, a good supply of goshawks. Why?

In spite of their fierce, formidable appearance, hawfinches are noted for being birds that build surprisingly flimsy nests. Many nests, like those in wild apples, are simply placed on branches, where the fluffy chicks stand out like pompoms on a tree. Or a nest might be placed in the ivy-clad cleft of an oak tree – often the first place that an aerial predator such as a jay will alight. Even in well-regulated woodland ecosystems like Poland’s Białowieża Forest, less than 30 per cent of hawfinch nests survive predation. Yet even this number is enough to ensure their survival. In other words, hawfinches have always been predated at the nest, and most nests fail. But their nest predators are supposed to be regulated, too. Jays are the main predator of hawfinch nests – and this is where the goshawk comes in.

Fieldworkers in the New Forest have found that hawfinches cluster almost all of their roosts, and many of their nest sites, within 200m of an active goshawk nest. Nest raiders like magpies and carrion crows, which can haunt the woodland edge, are often removed from play. Jays may still be present, but in lower numbers. In addition, the same fear factor that discourages bullfinches from open fields means that jays dare not linger long in the heart of a goshawk’s territory, reducing their time to find and predate hawfinch nests. Goshawks, by contrast, will rarely expend significant energy chasing birds like hawfinches, or other small birds, for food.

In helping to protect hawfinch roosts, goshawks allow these strange, parrot-like birds to carry out a range of woodland services. Hawfinches are one of few species capable of tackling the oak processionary moth, a sinister danger to oak trees if left uneaten. Most of all, they are the only aerial disperser of the wild cherry: no other flying species can penetrate its kernels.

In turn, by muscling buzzards and sparrowhawks out of a landscape, and eliminating a large proportion of its crows, goshawks are one of the most powerful and effective of winged gamekeepers, creating habitats where endangered smaller birds, and wader chicks, are more likely to survive. Yet, as the studies in Kielder Forest have shown, a goshawk unchecked can remove not some but all of the smaller birds of prey in a woodland. And if rodent-hunting species like kestrels vanish completely, there are other, less-welcome ramifications. Rats, for example, would greatly increase – and that, in turn, might lead to increased predation of the eggs of ground-nesting birds! As with anything involving birds of prey, all is not straightforward. Nature does, however, have a trump card designed to handle an ecosystem surfeit of goshawks. It’s giant, it’s silent, and a goshawk never sees it coming.

In parts of Europe such as Fennoscandia, a strange distribution befalls the owl population. Often, you will find a landscape full of middle-sized owls, such as tawny owls – but few small owls. In other landscapes, you will discover very big owls, and very small owls – but hardly any middle-sized owls. This peculiar situation arises because owls, like diurnal birds of prey, specialise in eating one another as well.

Both Ural and eagle owls, for example, will actively prey upon tawny owls, but seldom bother with the irate, feathered tennis ball that constitutes the pygmy owl. Pygmy owls, however, are often eaten by tawny owls. When giant owls are present in a landscape, however, they create the space for the smallest predators to survive. This came to the attention of ecologists in Germany, who were faced with a dilemma – the return of the goshawk was welcome, but their numbers had grown exponentially, and impacts were being noted on other species, such as honey-buzzards, at a landscape scale. So the scientists turned to the goshawk’s only natural predator – the eagle owl.

Of all the birds in Europe, nothing comes close to the predator clean-up operation run by eagle owls. In Norway, a third of all birds eaten by eagle owls are other birds of prey. Long-eared and tawny owls, buzzards and kestrels are commonplace prey – but so is larger game: goshawks, peregrines, and even the relatively large chicks of ospreys and white-tailed eagles. Since the reintroduction of eagle owls to Germany’s forests, densities of goshawks have declined by up to 50 per cent.

The secret to these extraordinary assassinations is that whilst those other raptors fly during the day, eagle owls hunt at night, when the raptors are tucked up and asleep. What would be an internecine conflict of talons, bills and blood by day thus becomes a swift and silent death by night. One nest camera, mounted on the cliff-side nest of a long-legged buzzard in Israel, gives some idea of how little chance a daytime raptor stands against a nocturnal super-sized owl. In the video, two young buzzards are dozing. Then, a fox-sized bolt from the black pelts out of the darkness, seizes one of the buzzards, the same size as itself, and vanishes into the gloom without even landing. The entire event takes two seconds. This is how eagle owls prey not only on smaller owls but also on goshawks, ospreys and even young eaglets. In some cases, the eagle owl will even eliminate all the birds of prey within a territory. As such, its effects on the ecosystem are profound. Whole orders of small day-flying birds, susceptible to daytime predators but secure in well-hidden nests by night, benefit greatly from the presence of eagle owls.

In the history of British birds, none has a more mysterious record of occupation than the eagle owl. We know these were native birds; fossils prove their existence as firmly as they do that of our elephants and aurochs. Eagle owls were present around Demon’s Dale, in Derbyshire, 10,000 years ago, but after that, the fossil record goes quiet. Eagle owls may have vanished from Britain even before the aurochs and Dalmatian pelicans. In some ways, this might not come as a surprise.

The eagle owl might not have been the friendliest of neighbours. Professor Ian Newton points out that not only does the call of the eagle owl, a haunting ‘boom, boom’ that bounces around inside your skull, and shivers your spine, carry for miles (and would have engendered much fear and superstition), but eagle owls are also amongst the fiercest of birds when defending their chicks. Their favoured rocky bluffs, bulging from sheltered hillsides, would have been the perfect homes for Homo sapiens. We know from cave paintings in France that humans watched cave lions and their prey from the safety of such vantage points. Sharing your home with a giant owl may have led to a conflict that could only end one way.

So incomplete is our fossil record of eagle owls, rather like the bison that must once have graced our shores, that tracing their departure proves difficult indeed. The discovery of a few bones hint at their presence in Somerset until 2,000 years ago, whilst reliable Victorian naturalists were describing eagle-sized owls in Scotland considerably later. For now, eagle owls rest under the label of ‘non-native’ species; a strange one indeed, given that they nest from the trees of Finland to the rock faces of Calais, within sight of Dover’s white cliffs.

Whilst eagle owls are long forgotten as native predators, and goshawks only beginning the process of attaining the numbers needed to influence ecosystems here in Britain, the absence of these predator-killers from large areas of the British countryside has led to other predators, those designed for the ‘middle’ of the food chain, to come out on top. And that brings us, in turn, to the extraordinary success story of the common buzzard.

The aerial fox of the countryside, mobbed by everything from crows to starlings, it can be easy to mistake the buzzard for the bumbling buffoon of the avian predatory kingdom. Lacking the muscular lethality of a goshawk or the pace of a peregrine, these lumpish raptors can neither soar as well as an eagle nor hover as well as a kestrel. But watch a buzzard for long enough, and you will witness a dozy brown lump transform into a rabbit-killing torpedo. Buzzards, when they wish, can stoop at over 100km per hour, and aerially ambush a range of wary prey from woodland jays to fleet-footed squirrels. A surprisingly large part of a buzzard’s diet comes from earthworms, but they will also harvest many of the lower levels of the food chain, from nestling and newly fledged birds to voles and amphibians. Buzzards share certain tendencies with their fiercer woodland cousin, the goshawk. They will frequently skim kestrels from their nests and muscle these small falcons off nesting sites in quarries and on cliffs. At the same time, buzzards can afford powerful protection to the small. By preying on large quantities of rodents, which can eat the eggs of ground-nesting birds, buzzards act to protect species such as meadow pipits, skylarks or corn buntings.

As buzzards have bumbled back into British airways, they have been greeted with applause by nature lovers. Now they grace the skies of every county in our island. In the wave of enthusiasm, conservation groups have argued that buzzards, as well as red kites, are welcome ‘apex predators’. But in the red-taloned world of raptors, buzzards do not rank highly: classic mid-order or ‘meso’ predators, they are more suited to a role of limited power. If one reason for this is the power of the goshawk within woodlands, the other is merely a matter of size. Buzzards, in turn, would once have bowed to eagles.

In many ecosystems, from the river valleys of southern Africa to the Spanish hills, from the lakes of northern Finland to the coast of Japan, all functional ecosystems need giant aerial scavengers. As far as we know, Britain has never played home to vultures, but nor has it needed to do so. Britain’s vulture niche was, and is now again being filled by a far more versatile bird – the white-tailed eagle.

Prior to the Bronze Age, as wild horses perished from old age in winter hilltop blizzards, the white-tailed eagle would have closely followed ravens to a carcass, scattering them as it alighted. As the written records of Saxon battles attest, as the dead fell, so eagles would swoop from the skies. Yet the white-tailed eagle has a versatility rare in any bird of prey. Not only a consummate scavenger, it can also kill a greylag goose on land as effectively as it can rip a salmon from the water. Whilst tied largely to water, it can nest anywhere from giant pine trees to hanging willows and, if short of options, it will even build floating platforms in the reeds. Hunting deltas, floodplains, ponds and the coast with equal ease, white-tailed eagles are a species built for versatility, abundance – and dominance.

So persecuted have eagles been over centuries, so degraded their habitat, that we have come to cherish them as rare. Yet the designs of an ecosystem necessitate that white-tailed eagles, like any apex scavenger, should in fact be common. And when undiminished by habitat loss or human depredation, they are. Protected since 1919, Russia’s Volga Delta is one of the only places in Europe where the preservation of original habitats has been matched by a century’s fierce legal protection. Recalling the Somerset marshlands of 3,000 years ago, the Volga reminds us of a world that only Britain’s Neolithic ancestors would remember. In all, one thousand white-tailed eagles feed and nest here in the Volga, in an area of willowy marshland smaller than Norfolk.

Extrapolating from such natural densities, contemporary estimates that Britain held around 1,400 pairs of white-tailed eagle, prior to their eradication, seem extraordinarily low. In the Bronze Age, large wetland systems covered 20 per cent of Britain – the greatest being in the mosslands of Cheshire, Somerset, the Humber estuary and the huge fens of present-day Lincolnshire and Cambridgeshire. Each of these wetlands alone may have been large, and prey-rich, enough to host 1,000 white-tailed eagles.

Early on, however, Mesolithic settlers moved into these marshlands, living on boardwalks and in small boats. The audacious white-tailed eagle would have competed with them for food. Centuries later, it is thought medieval monks, tending fish ponds rich in carp, would also have been ‘plagued’ by these birds. As we drained Britain in the seventeenth century, we would drain our lowland eagles. For centuries, we drove them to our coasts, then wiped them out. Birds remained for longer in Scotland – and eventually we cleansed them from here as well. Yet even as the white-tailed eagle was being hunted out of Britain in the early nineteenth century, we are reminded of its onetime abundance here on our own shores.

The records compiled in Roger Lovegrove’s Silent Fields reminds us that on one Sutherland estate alone, home to numerous fish-rich lochs, 171 adult eagles and 53 young were wiped out during the 1820s alone. Such localised examples of abundance suggest that centuries before, the lowlands, sea bays, wetlands and rivers of Britain may have been home to several thousand pairs of white-tailed eagles. These birds had evolved, like the vultures of Africa and India, in an age of plentiful herbivore carrion, and fish. They had evolved to be common.

In recent decades, thanks to pioneering reintroduction schemes, Britain’s ‘flying barn door’ has recolonised a little of its former range, with more than 100 breeding pairs. At the time of writing, birds reintroduced to the Isle of Wight are now gracing English skies for the first time in centuries. Yet today, white-tailed eagles remain so rare that we have forgotten the fundamental role their circling flocks once played in altering the landscape. Their effects upon fish, and fishing, would have been profound.

As well as eating their fair share of nestling buzzards, and displacing others from their territories (buzzards would never have attained their numbers here in Britain, had the white-tailed eagle been present in its former numbers), white-tailed eagles bring to heel that most ‘insatiate’ of birds, the cormorant. In northern Germany, entire colonies are forced away from prime fishing grounds due to heavy predation on their chicks. Cormorant colonies coming under attack are prone to panic; fleeing their guano-washed nests, they leave their chicks to be harvested on repeated visits by eagles.

Heronries, too, are often moved or displaced by the threat of white-tailed eagles. Large colonies, capable of reducing fish productivity, are fractured into smaller ones. Scattered across the landscape, these refugees come to have less effect upon a wetland, dispersing the prey-base for a wider array of other species to profit from. Birds like herons and cormorants are elegant and graceful, yet the latter, in particular, is one of the most intensive hunters on the planet. Unchecked, cormorants can decimate fish-stocks; the white-tailed eagle prevents this. In suppressing the most demanding anglers in a wetland, yet taking only far smaller quantities of fish themselves, white-tailed eagles ensure that sufficient stock exists to replenish the population the following year.

In undiminished abundance, the effect of gregarious fish-eating eagles grows greater. In Alaska, the bald eagle has recovered to a far greater degree than its European cousin. Each autumn, thousands of eagles, dispersing from breeding grounds along the coast of British Columbia, gather to feast on the post-spawning carcasses of fish, in rivers that still run red with salmon each fall. In scavenging the salmon, flying with them to perches and losing others during aerial squabbles, bald eagles fulfil the aerial role of bears, dropping the remains of nutrient-rich salmon to fertilise the land. Long ago, when British coasts wriggled with spawning salmon, white-tailed eagles would have carried these ashore. In doing so, these birds would have played an important role in fertilising the lowland woodlands of our coast – acting as nutrient vectors, transforming the very composition of the soil – and the trees that grew within the Atlantic rainforest.

White-tailed eagles may be the largest birds of prey ever to have graced our island, but alighting at a carcass, even they can defer to one other. Peregrines flee before this eagle. Buzzards and hen harriers move home to avoid it. It regulates the land with some of the keenest eyes on Earth and talons that can pierce the backbone of a wolf. Of all our flying creatures, not since the age of dinosaurs has one more powerful graced Britain’s skies.

Golden eagles are regarded the world over with reverence and awe. They are the most powerful aerial hunter in much of the world, outside the tropics. With a grip 15 times the strength of ours, they know few limits in the prey they are able to capture. Documentary video evidence shows that golden eagles trained by Mongolian falconers can not only capture but also dispatch adult wolves, though fights do not always go their way. In Britain, livestock predation is extremely rare, yet in one extreme but well-documented incident in New Mexico, a particular population of eagles felled 12 domestic cattle calves, some exceeding 100kg in weight. Pairs of golden eagles in North Macedonia have been known to specialise in horses.

The scale and audacity of the golden eagle’s hunting operation is known only to a few. In Sweden, a young lynx was found in a nest. Young otters and badgers have been brought to Scottish eyries. Red foxes are commonly taken, making up more than a tenth of the eagle’s diet in places such as Sicily. Roe deer are not only frequently killed but also carried to the nest: in the Italian Alps, up to a third of the nestling diet consists of this fleet-footed ungulate. Red deer calves can be carried off. On the Swedish isle of Gotland, half of the eagle’s diet consists of hedgehogs. In Alaska, brown bear cubs have been whisked away. In Europe, Hermann’s tortoises have gained surprising turns of speed in their final minutes. Across mainland Europe, wild boar piglets have gained the power of flight.

By contrast, records of golden eagles being killed are as rare as might be imagined. In one case, an overambitious bird died in a fight with a snow leopard. In Scotland, an eagle seeking to attack wildcat kittens died in a fight with their irate mother, who was also killed. In Alaska, only adult brown bears regularly dare to raid the ground nests for eaglets to eat. Barring perhaps the orca, golden eagles may be the most widely feared of the world’s apex predators.

Whilst small birds sharing the realm of eagles have little to fear, the same cannot be said of the birds of prey, crows or other large birds that fly where eagles dare. In Estonia, cranes are regularly eaten, and, in northern Norway, mute swans. Golden eagles will regularly kill buzzards and hen harriers, or push them into areas of marginal habitat. They will drive peregrine falcons from their nesting cliffs. In the Galloway hills, in the 1940s, when golden eagles returned after a century of persecution, each pair would displace a peregrine from its ancestral cliff-top home. In Europe, even the Ural owl – a huge, deceptively calm-looking owl famous for striking at the eyes of humans – is not beyond a golden eagle’s reach. Even goshawk-killing eagle owls have, on occasion, been discovered in an eyrie. In most direct interactions with white-tailed eagles, golden eagles win. At carcasses in Finland, the larger eagle inevitably gives way to the superior talons and supercharged ferocity of its muscle-bound predatory peer.

So early did golden eagles lose their wilderness and habitat in Britain, we have all but forgotten them except as Scottish birds. For centuries, no one has watched golden eagles harry deer on the hills of Snowdonia, or power through Dartmoor’s steep valleys in search of woodland grouse. Yet these sights were once our ancestors’ to enjoy.

Reconstructions of the golden eagle’s former range in Britain have found it present throughout the hills of northern England and Wales. The fossil record records eagles from Fox Hole Cave in Derbyshire, an area of low hills east of Chesterfield. Their bones have also been found at Catterick, an area of moorland in Yorkshire, and in the Ossom’s Eyrie Cave in central Staffordshire. None of these sites, incidentally, falls within the high, forbidding mountains that we might associate with this species in Britain today.

Not only do bone remains from Stafford Castle date into the sixteenth century, but reliable eyewitness accounts are also surprisingly recent. Eyries were found in Derbyshire’s Derwent Valley until at least 1668, and in North Yorkshire until the 1790s. In Wales, eagles were still nesting on the cliffs of Llangollen in 1656, and until 1800 in Snowdonia. More recent studies have further ‘expanded’ the range of Britain’s aerial masters. One study, analysing old place names in relation to the habitat of white-tailed and golden eagles, has found good evidence that golden eagles hunted Dartmoor a millennium ago, whilst some naturalists’ accounts appear to reliably detail golden eagles on Dartmoor as recently as the early 1800s. Yet even these records are unlikely to reveal the whole picture.

As with so much of what we have lost, ‘shifting baseline’ syndrome has led to ecological amnesia amongst many of Britain’s naturalists. We have assigned golden eagles to steep crags and mountain ranges, forgetting that they have, over millennia, become mountain refugees. Studies have assumed that eagles stop where mountains end. Yet given any choice in the wilderness they hunt, golden eagles can breed and thrive in lowland areas as well.

In countries like Estonia, where the undisturbed lowland forests lost to Britain in the Bronze Age still grow intact, eagles build their largest nests in giant pines. Here, they breed successfully in remote areas where grouse, deer and hares form much of their diet. Estonia’s low open wetlands are ruled by white-tailed eagles; its remote, broken forests by their golden cousins.

In addition to enormous areas of dry forest – far from water and unsuitable for white-tailed eagles to hunt – rich lowland forest and bogs would have been found within many British wetlands. The fossil record details golden eagle bones from Meare Lake, in Somerset, as late as the Iron Age. If not from Somerset’s marshlands itself, perhaps this eagle had ventured over from the Mendip Hills, where its bones have been unearthed in Cheddar Gorge. Dense Atlantic rainforests, greening the steep, cliff-rich hills of Wales, Exmoor and the Mendips, would, prior to their deforestation, have suited golden eagles to perfection. Now, long forgotten by us, the British landscape still feels the gaping loss of its golden eagles.

In regulating all flying predators, deer and ground predators such as foxes, golden eagles free up whole orders of the animal kingdom to go about their daily business, and can even protect ecosystems against overgrazing. By pushing small hunters to the margins, golden eagles guard the realm of the small, the fragile and the young. In preying on young foxes and badgers, golden eagles create a landscape of fear, where ground hunters dare not wreak havoc for long. And in taking such a broad diet of animals, as generalist predators, golden eagles never exert too much pressure on the survival of any one species. Their role in the wild is as finely balanced as their perfect silhouette. And the golden eagle is the final, greatest piece in the seemingly paradoxical puzzle of birds of prey: those species who, through killing, simultaneously protect and enhance the natural world.

It is very hard, however, for many British people, or indeed those in most of the industrialised world, to grasp the true power and importance of birds of prey – large and small – for the simple reason that we now have so few. But what would happen if these diverse hunters were restored to their original numbers, across ever-expanding tracts of suitable habitat? What would happen if we briefly turned back the clock 5,000 years, to a time when eagles governed every British airspace? To get some idea, we must look, for now, to those parts of the world where birds of prey have never vanished at all.

In 2019, I spent over eight weeks in the Luangwa Valley of Zambia, an area of untouched river valley and wood-studded savannah larger than Yellowstone National Park. Few places on Earth may be considered truly pristine – but Luangwa is as close as it comes. For centuries, sleeping sickness and the impossibility of farming has preserved an ecosystem not dissimilar in magnificence to that last seen in Europe during the Pleistocene Era. Whilst the ever-vying lions, wild dogs, leopards, hyenas and crocodiles are the familiar ground predators that help protect the diversity of this landscape – preying upon the sick and weak, and preventing Luangwa’s diverse herbivores from grazing down its scrubland, grassland and trees – fewer tourists here look to the skies. In reality, one of the greatest guarantors of biodiversity in this landscape is a teeming abundance of different birds of prey.

South Luangwa National Park, covering 9,000km² of Africa, has seen the poaching of rhinos in recent years, but there is no evidence that its birds of prey have ever been persecuted, or their habitats fundamentally altered, in the past 10,000 years or more. Everywhere you travel, birds of prey abound, each governing its niche within a hostile wider kingdom. Large kettles of vultures, in their dozens, forever scour the landscape, as white-tailed eagles once did in Britain, seeking fallen herbivores; some felled by disease, others by lions, hyenas, leopards or dogs.

Martial eagles, capable of lifting impala from the ground, relentlessly hunt grazing animals from gazelles to scrub-hares; protecting, as they do, the grasslands and new trees, none of which would form were small herbivores alone left in charge. Lizards abound in the grasslands, scoffing many large grasshoppers on which shrikes depend – but many will be carried off by the lizard buzzard. A rich chorus of scrub-dwelling songbirds, denser than any left in Europe, haunts Luangwa’s diverse bushlands, but they will never get the chance to harvest more than a portion of its small invertebrates: each is being watched by predators from the little sparrowhawk to the Gabar goshawk – no sooner has prey filled a niche than a predator is on the scene. Fish flourish across the river valley, but they will not divest it of small, aquatic life; a large population of African fish-eagles see to that. The plentiful African guineafowl here feast upon beetles and weeds, but they will decimate neither: the African hawk-eagle keeps them in check. Venomous snakes haunt the grasslands here, killing many of the rodents that would eat birds’ eggs. But they will never eat them all: no fewer than three species of snake-eagle act as airborne anti-venom. Ground-nesting waders, such as lapwings and thick-knees, may be sometimes plagued by birds that rob their nests. But should those robbers hesitate an instant, a hawk, buzzard, falcon or eagle would be upon the scene. In Luangwa’s skies, for every check, there is a balance. For every order in the animal kingdom, forever threatening to grow out of control, there is a bird of prey. One day, we may once more enjoy the same here in Britain.

Even now, it is possible to restore birds of prey to all corners of our land. And as we restore our ecosystems, we will begin to see the effects of birds of prey once again. From the sparrowhawk’s safeguarding of wood ants and fruit trees to the goshawk’s protection of the hawfinch; from the white-tailed eagle’s protection of fish stocks to the golden eagle’s dominance over buzzards and crows, all of our aerial predators have a vital role to play – the protectors of a song-filled world that we all wish to inherit and enjoy.