Even within that harrier zone there are demarcations – holding patterns – for each of the harrier species. The marsh harrier tends to fly a little higher than its congeners, the hen and Montagu’s harrier, relying more on its eyesight than the other species to peer down into the tall reed beds that make up so much of its hunting range. The hen harrier (the greater vole specialist) hunts perhaps the lowest of the three, scything the ground. The hen harrier also has the most pronounced facial ruff of the three resident British harriers. And as the ruff is the harrier’s radar rim, of the three species, the hen harrier has evolved the most efficient sound detector to pick up the minute patter of a vole moving through its grassy tunnels.
But the marsh harrier is as much a sound detector, as much a listener-in as its harrier cousins. And the panicked splashing of a duck with her flotilla of ducklings through the reeds must flood the marsh harrier’s hearing. At night, roosting on the ground, often in open spaces, harriers depend on that hearing to listen out for threat. Roosting sites are selected for their acoustic properties: reed beds, barley crops, dried mudbeds, all places that crackle and ripple when entered by a predator. A bird that can detect the sound a locust makes feeding along a branch must also hear the footsteps of a fox.
The harrier’s face is a scoop, a shallow drinking cup, an Elizabethan face, rimmed by the silky, light-reflecting ruff. The ruff itself is like a thick plait, a ring of closely packed barbules layered around a rim of skin. The ruff can inflate, puff out, increasing the surface area of the face, increasing the harrier’s ability to capture sound. The face is really a giant ear. It works like an ear, or, rather, serves the ears, scooping up sounds and channelling them into the large ear openings set behind the eyes. The harrier’s facial disc is always working, drinking up sounds, weighing them, tasting them in the feathers’ nerves, reflecting them back off the ruff, through the ear-coverts, into the large ears.
I walk north-east across the saltmarsh, following behind the two harriers. In the distance: a hamlet crouched low on the headland, hunkered in on itself. It is slow going against the headwind and I am amazed any bird could beat into such a wind. Then I reach the island’s east coast and there is the sea again, brown and unrecognisable. I walk up over the dunes and peer down at the beach. Between the narrow road and the dunes is the most incongruous sign, as bizarre as my ostrich encounter in the fog above Bolton: This Stretch of the Beach is Dedicated to Naturist Bathers. The thought of being able to take your clothes off, let alone bathe in such a place … It is impossible to imagine the beach in light and warmth. There is no shelter, even among the dunes, and the beach is all crashing, roiling noise, spume-flecked, wind-wrecked, abandoned to the gulls and wading birds. Past the dunes: a bric-a-brac of summer beach huts and hauled-up, upturned boats, the colour gone out of them, everything shut down and weighted down by stones and ropes. A place in such deep hibernation you could kick and yell at it and it would not stir. In front of the huts the beach is demarcated with wooden groynes, the space between each of them filled with wind and shrieking gulls.
I turn at last inland. A brief dose of wind-relief as I shelter behind a caravan on its breezeblock stilts. I watch a flock of lapwings shivering over the fields. Then, glancing past the lapwings, closer to me, a marsh harrier: a male, working the seam of a ditch, gliding low over an abandoned saltworks, flying into the wind to slow himself down.
The harrier hunts through an interplay of sight and sound. The harrier’s ears are not positioned asymmetrically (like an owl’s), so it does not possess the owl’s supreme ability to pinpoint prey in the dark. But, for the harrier, hearing and vision work off each other and a movement through the reeds can first be detected through the ears before it is homed in on with the eyes.
The marsh harrier is as much a generalist predator as the red kite and sea eagle. Almost anything is taken where available: insects, crustaceans, fish, snakes, birds, small mammals … In the British Isles the largest prey is an adult duck. Unlike the other harriers, the marsh harrier will also occasionally feed on carrion, its larger size and larger bill enabling it to compete amongst the other carcass-squabblers, the corvids, kites and buzzards. The marsh harrier specialises only when there is something to specialise on, when there is a glut in a particular prey species. But it is not reliant on a specific prey as other raptors – the vole specialists – are. Young moorhens, coots and rabbits are taken in the summer months. Also, partridges, skylarks, rats, small coypus, where available. In Kent, the marsh harrier is known as the coot-teaser (other local, archaic names include: bald buzzard, white-headed harpy, duck hawk, moor buzzard). It will repeatedly dive at coots and water-rail to exhaust and drown them, much as the sea eagle does. Marsh harriers have been known to barge the smaller Montagu’s harrier off its prey. They have even been observed trying to knock an adult female pheasant off her feet to get at her chicks sheltering beneath.
They are more methodical too, marsh harriers, in their hunting than the hen and Montagu’s harrier. Marsh harriers do not range as far when hunting (certainly nothing like as far as the long-distance foraging of the Montagu’s harrier). The marsh harrier will work a patch of reed bed over and over, scrupulously checking it for the slightest movement, the slightest leaf shiver.
They rarely give chase. Marsh harriers rely on surprise and ambush, coming across prey unawares in the reed beds and ditches. But just as they hunt through the interplay of sight and sound, marsh harriers also hunt through a blend of search and flush, alternating their speed and height, leaning, like the other harriers, into a head wind to slow themselves, rising to take a closer look inside the reed bed, or, rushing low over a drainage dyke, hoping to surprise prey feeding on the marsh below the dyke. The male marsh harrier, his pale underside merging his outline with the sky, hunts more than the darker female over open spaces. The larger female is the reed-bed specialist. But both sexes prefer a broken landscape where they cannot be seen coming, where they can utilise landscape features – ditches, hedges, field edges – to surprise their prey. Often the harrier spots prey having already flown over it, performing a split-second somersault, tracking back to drop with wings held back and legs stretched out in front to make the strike.
Mostly it misses: most birds of prey miss most of the time. They are not the super-efficient predators we take them for. Five to 10 per cent is around the average success rate for raptors. Estimates for the marsh harrier are slightly higher, 5–17 per cent. One study in East Anglia gave a success rate of 27 per cent, though killing is hard to monitor because so much of it goes on out of sight in the deep reed beds. Young raptors chase everything and miss almost everything. They learn quickly what is suitable and what should be left alone. They learn to read the signals: coots flick their white tails at marsh harriers when they are still a long way off, saying, We have seen you, we can see you coming, don’t bother yourselves with us. Skylarks, singing vociferously over the moor, are saying to the merlin, Listen, I am loud and fit and can climb as far as the clouds if you try to pursue me. Save your energy, don’t bother with me. The myth is that killing is easy, that all the osprey has to do is turn up and fish will float to the surface, belly-up in submission. Most raptor prey is quick to adapt to predation. Raptors tend to hunt routinely, predictably. A marsh harrier will cover the same ground daily, often for years on end. Their prey know they are there: many small mammals seek out the cover of denser vegetation or make use of heavy rain (which grounds birds of prey) to do their foraging.
The marsh harrier kills with its talons, a seizure in the foot. The rear and front talons grip then squeeze, puncturing the prey from either side with the harrier’s long sharp claws. If this does not result in death, prey can be stabbed with a talon or, more rarely, with the bill. Larger mammals are then skinned, the skin pulled down neatly like a sock from the head down over the rear legs. Avian prey is plucked then stripped of its flesh by the harrier’s strong bill.
Enemies: heavy rain, bitterns, foxes, egg collectors, wild boar, mink �
� Bitterns (who will eat anything, including marsh harrier chicks) are the marsh harrier’s sworn enemy. As the raven is to the red kite, so is the bittern to the marsh harrier. Bittern-baiters, harriers will persistently mob any bittern that comes too close to their nest. The marsh harrier will swoop down at the bittern, veering up at the last moment as the bittern jabs its long spearlike beak at the harrier to ward off the attack.
I stand beside the caravan for a while, enjoying its shelter, hoping the marsh harrier will come back. But he has moved on, hunting the fields way over to the west, so I turn north and walk along a frozen farm track. I pass some outbuildings on the edge of a farm. I can see just an arm’s depth into their open doorways, bridles on a nail hook, a lasso of blue bailer twine. Manure heaps beside the track are bulbous under the snow. I can still hear the sea. Between the track and the sea there is a narrow field with a thin windbreak of stunted birch trees.
I don’t know why I stop there on the track, gazing through the swept-back trees at the muddy sea. I think I am just tired after walking into all that wind and I like the shape the dungheaps make under the snow, glandular, like giant puffballs. But then, out of the trees, racing towards me: a female sparrowhawk, the last bird I expect to see out here in the marshes. A burst of speed, then my binoculars find her and I can see the black and white patterning of her breast. It makes no difference to the hawk that I am here. What happens next carries on around me and close to me as if I’m not here at all. I stand on the track and watch the hawk fling itself at a blackbird, a glossy black male. The blackbird is on the ground, close to the fence that borders the track and the field. He is scolding hysterically, frantic with alarm. With its first stoop the sparrowhawk misses, lands on the ground beside the blackbird and proceeds to pounce at it, stabbing at the blackbird with its long yellow legs. The blackbird easily dodges the stabs. So the hawk tries again, lifts up, hovers a couple of feet from the ground, and flings itself once more at the blackbird. Again the blackbird easily steps out of reach and it seems to hold the advantage, the hawk has lost the element of surprise and it has too little space to use its speed. The blackbird, it seems, has no intention of taking flight. But the hawk will not give up, it keeps lunging at the blackbird until the blackbird has pressed itself right up beside the bottom of the wire-mesh fence, as if it is trying to squeeze itself under the fence. The hawk cannot risk flinging itself at the blackbird in case it misses and crashes against the fence. So it is finished: the hawk lifts off the grass and flies straight back into the trees. The blackbird, still scolding, shoots off low across the track and into the adjoining hedge.
I thought that was it and the sparrowhawk had gone. But she is suddenly flying back out of the trees and flinging herself at a large mistle thrush crossing the field between the track and the wood. The gap between the two attacks is barely a minute. The hawk seems exhausted, grabbing at the thrush, stabbing at it with its legs. Always missing, the thrush easily dodging the hawk’s talons, feinting, checking, sidestepping away from the hawk. And once the thrush has twisted out of the momentum of the hawk’s attack, it is over and the sparrowhawk turns away and flies back into the bare wood. For a few minutes afterwards I watch her burning in her hunger-rage through the trees, unsettled, skidding from branch to branch. Above the spinney, flocks of woodpigeon, like a weather system, stream over the trees on their way to roost.
Of all the British birds of prey the marsh harrier inhabits the most specialised habitat. It is a bird of the reed and the wet, the marshlands and fenlands, the border zone between land and water. The reed bed is the marsh harrier’s backyard; in French it is le busard des roseaux (the harrier of the reeds). To hunt across such a landscape it needs to be able to listen deeply, see deeply and stretch deeply. So it has evolved the longest legs and largest feet of all the harriers and its greater size enables it to kill much larger prey than the hen and Montagu’s harrier can.
Where it nests, in the deep reed beds, amongst bulrush, bur-reed, reed buntings and bitterns, is as remote and inaccessible as the peregrine or golden eagle’s cliffside eyrie. A reed bed is the most difficult, unnavigable landscape to try and move through. I tried it once, late one summer (after the nesting season was over), walking through a huge reed bed on the Tay estuary. It was muggy and the river smelt of warm mud and rotting vegetation. On the path beside the river I almost stepped on a rabbit with foamy myxomatosis eyes. The rabbit sensed me and leapt awkwardly to the side, spraying dew from the long grass where it landed. I walked down a steep bank through thigh-deep thistles. Reed buntings were clicking all around me and through binoculars I could see the streaked patterns on their pale breasts and the distinctive black heads of the males. A female marsh harrier was cruising over the beds below me, her brown back the same colour as the reeds’ seed heads. I could just make out her pale silver throat and nape. She circled briefly over a cornfield above the river, stirring up house martins that looped around her in agitation. Then she was out over the beds again, sweeping their expanse. In the distance, I watched her suddenly check her flight, turning right around. She swooped down towards the reeds, paused, then dropped into the reeds and out of sight.
I found a narrow path somebody had cut into the reeds and followed it. More like a tunnel than a path, the reeds completely dwarfed me and leant over to touch each other to form a roof. But then the path just stopped and I was confronted by a 10-foot-high wall of reeds in every direction. I tried to wade into them but it was impossible, I could not see where I was going and I needed a machete or stilts, or both. It was the most claustrophobic space I have been in, the reeds were so ungiving. So I gave up and waded back to the small clearing where the path ended. When I had stopped and caught my breath it was quiet inside the reeds. The place had its own acoustic reach, insects – the whirr of mosquitoes – were amplified inside the reeds. The floor of the bed was an oily black mud, I would have sunk into it if it wasn’t for the broken reeds that lined the path and supported my weight.
Later I found a section of the path where the reeds were not quite so high and I could stand looking out across acres of reed bed. I enjoyed this new perspective, eye level with the tops of the reeds, at the same height as the marsh harrier cruising over them. I often seek out these sight-angles, try to get myself, if possible, at eye level with the birds. I had done this with the peregrines at the top of the cathedral tower in Coventry, the red kites on the hill above Llandovery and the golden eagles on the mountain tops of the Outer Hebrides. With harriers there is much less of a climb, you just need to find somewhere suitable to hide. Then wait, keep watch: the harrier’s flight level is often as low as your eyes.
Perhaps more so than any other bird of prey the marsh harrier just needs to be left alone. They need the isolation – the strange quarantine isolation – of the reeds. They are the most fragile and flighty of raptors, easily spooked, easily disturbed. It does not take much for them to desert their nests: children splashing in a nearby pond, pleasure-boaters, a clumsy wildlife photographer … The Danish ornithologist, Henning Weis, who studied both marsh and Montagu’s harriers in West Jutland between 1913 and 1918, put it best when he described the marsh harrier as a creature of infinite caution and wariness towards everything unknown. One incident Weis records in his beautiful book Life of the Harrier in Denmark perfectly illustrates this caution in the bird. Weis was attempting to photograph a family of marsh harriers when the adult male bird spotted him crawling out of his hide in the reeds close to the harriers’ nest. Weis at once destroyed his shelter but neither of the harrier pair landed in the nest again. Instead they dropped food down to the young as they flew over the nest. Eventually the adult birds persuaded the young harriers to abandon the nest site and move to a new location some distance away.
Henning Weis felt that this innate wariness was probably the only reason the marsh harrier still existed in Denmark, though he was pessimistic about its chances of surviving as a breeding species after the brief respite of the First World War. Once wildfowlers retu
rned to the marshes again after the war was over Weis was sure the marsh harrier would be done for in Denmark. In Britain extermination of the species was more advanced. The last known breeding pair of marsh harriers were trapped in Norfolk in 1899. They had once been so common in that county they could have been named the Norfolk Harrier. And across the border in what is now Cambridgeshire, Whittlesea Mere, before it was drained, had been a mecca for the harriers, a place where oologists returned again and again to collect their eggs.
Gone by 1899; crept back in 1911; bred again in Norfolk in 1915. But the marsh harrier’s status was so tenuous, so precarious, for many decades it was easily Britain’s rarest bird of prey, rarer even (and you would not think this possible) than the red kite still clinging on in Wales. Numbers were boosted a little by wartime coastal flooding where land was deliberately flooded to deter invasion. Even more land was abandoned to the reeds along the Norfolk and Suffolk coasts after the devastating tidal surge of 1953, and by 1958 there were fifteen nests in Britain. Then came the pesticide years: eggshell thinning, convulsions, death by poisoning. By 1971 their numbers had plummeted to just one nest in the entire country, and the marsh harrier was the country’s rarest breeding/not-breeding bird of prey again. Just as the red kite was exiled, banished to the remote Welsh hills for the first half of the twentieth century, so the marsh harrier, during the same period, was kept in check, contained within a small corner of the Norfolk Broads. For decades the marsh harrier existed as a fragment of itself, a sprinkling of birds holed up – held up – in the marshes of Hickling and Horsey. The birds were held there in a quarantine of sorts, any attempt to colonise neighbouring areas being met with persecution, exclusion.
Marsh harriers were not resettled – not reintroduced – in the way that the red kite and sea eagle have been. They just came back of their own accord once the persecution abated. There are now over three hundred breeding pairs in Britain and they can be found in wetland habitats between the east coast of Scotland and the south coast of Dorset. Some of these, like the Montagu’s harrier, are migratory, but recently, as winters have become milder, British marsh harriers have also begun to overwinter here.
Raptors Page 19