Читать книгу Bowland Beth: The Life of an English Hen Harrier - David Cobham - Страница 9

The male hen harrier, on his way back to Bowland, had overnighted in that part of the Peak District known as the Dark Peat. As he took off from his roost where he’d been safe under cover, hidden from sight by a few stunted trees and warm in the comfort of the sphagnum bog, he noticed the almost complete absence of other birds of prey – no harriers, peregrines or goshawks, just the occasional merlin or kestrel. It was not a good place to be a bird of prey. Like all hen harriers he had a distrust of man. The sight of a line of men managing a heather burn made him jink to one side to avoid the billowing flames and smoke.

Much of the heather moorland is managed for the benefit of those who shoot red grouse. The birds are driven towards the ‘guns’ waiting in a line of butts set up across the moor during the grouse-shooting season, which starts on 12 August and ends on 10 December. There are four main grouse moors in Bowland – United Utilities (formerly North West Water Authority), Abbeystead, Bleasdale and Clapham estates. There are other smaller moors, all of which are important players in their own way.

The United Utilities estate is not a true moor, nor is it managed to the extent of the others. There is some driven grouse shooting but the majority of the grouse killed are shot by a single gun walking the moor with setter and pointer dogs ranging ahead. If they find grouse, the pointer holds its point on the crouching birds. The gun moves up and the setter flushes the grouse, allowing the gun two shots at the grouse as they fly off. It is good exercise, and was the method used when grouse shooting started in the north of England and Scotland at the beginning of the nineteenth century.

In 1831 the Game Act was passed to protect the interests of all those preserving game for shooting, setting dates in the calendar between which it was permitted to shoot different species of bird. It also gave gamekeepers the power to carry weapons and to arrest poachers. This set in motion a chain of events that ensured that the goshawk had disappeared by 1889, the marsh harrier by 1898, the osprey by 1908, the honey buzzard by 1911 and the white-tailed eagle by 1916.

It was a prosperous time in England and rich sportsmen lusted after shooting increasing numbers of grouse, just as they shot driven pheasants flying out of a covert. This passion for driven grouse was aided midway through the nineteenth century by two factors: Queen Victoria’s love affair with Scotland – and Balmoral in particular – and the expansion of the railways.

So how does driven grouse shooting work? The moor is divided up into a number of beats, and towards the end of each beat a line of six to eight butts – breast-high embrasures, behind which stand the guns – are positioned. A line of beaters, starting from the far end of the beat, walks slowly forward through the heather towards the butts. The red grouse, which tend to congregate in packs at the end of the breeding season, are flushed and fly very fast at shoulder height towards the guns. Good shots kill two birds in front, take their second gun from their loader, who is standing behind them to their right, and shoot another two birds as they fly away. It is the kind of shooting that sorts the veterans out from the rookies.

Over time the grouse shooters demanded grouse in ever-increasing numbers. This led to overstocking, with more grouse left in the winter than the moor could sustain. Two diseases – strongylosis (caused by a worm in the gut) and looping-ill (a tick-borne disease of sheep) – found ready purchase in the weak birds and were to bedevil grouse-moor management for many years to come. Grouse disease was such a problem that the government stepped in and commissioned a two-volume monograph, The Grouse in Health and Disease, published in 1910. Dr Edward Wilson, one of the heroes of Scott’s ill-fated attempt on the South Pole, was among the team that compiled the report.

They concentrated on strongylosis and succeeded in plotting out the disease’s life cycle. Sometimes the disease can develop very rapidly, completing its cycle in fifteen days. The larvae hatch out in the droppings of the grouse and then climb up to the green shoots on the heather. The grouse eat the green shoots and larvae, then the larvae grow to their adult stage in the grouse’s gut and reproduce, laying eggs. They pass out in the grouse’s droppings for the cycle to be repeated. All red grouse carry strongylosis and late spring – April to May – is when the disease peaks. Allowing too large a stock of birds for the moor will lead to a periodic epidemic.

It is an interesting sidenote that in 1908 a protozoan parasite was discovered, Cryptosporidium baileyi, that affects poultry. A hundred years later it would cause what is known as ‘bulgy eye syndrome’ in grouse, and had a devastating effect on driven grouse shooting when the moor was left overstocked at the end of the season.

Not long after the discovery of Cryptosporidium baileyi, driven grouse shooting and the number of grouse shot were reaching their apogee. I consulted Record Bags and Shooting Records by Hugh S. Gladstone for information on numbers of grouse shot, and discovered that on 12 August 1915 at the Little Abbeystead beat in the Forest of Bowland eight guns shot 2,929 red grouse in six drives, a record that stands to this day.

For several days the female hen harrier, number 22, tried to return to her birth place but was put off by the heather burning on the moorland below the ridge. Now, as she wheeled high above, she could see that the men had gone and all that was left was a mosaic pattern of blackened, burnt areas. Cautiously she drifted lower and then made several passes along the ridge until she was satisfied that it was safe. She dropped down and landed by the bilberry patch she remembered so well. The sky darkened as a ragged shower of rain swept across the moor, dousing those newly burnt heather patches, which were still smouldering.

Heather burning is part of the history of driven grouse shooting, a sport that started in about the middle of the nineteenth century. Beforehand moor owners had derived income from farmers wishing to graze their sheep, and the farmers burnt the heather to improve the grazing. Moor owners realised that they could receive a better income from driven grouse shooting than from sheep grazing, so heather burning was banned. All went well for a few years until grouse numbers suddenly collapsed. What the moor owners hadn’t realised was that red grouse eat heather shoots virtually throughout the year. Burning was quickly reinstated, with the aim of burning patches of heather on the moor when it was about ten years old. Burning at this age stimulates regeneration of growth from the roots to provide the green shoots that grouse feed on. If the heather is not burnt until it is fifteen or twenty years old there will be a very hot ‘burn’, caused by the long, woody heather stems – and there will be no regeneration.

The burning, which starts in October and continues until April, should produce a mosaic of burnt areas (an area burnt this year, last year and so on), the areas becoming greener and greener as the heather regenerates, with the edge of each burn ragged rather than straight. During the first fortnight after they leave the nest, grouse chicks feed on insects and wander into the open, and ragged edges gives them a chance of escaping a hunting hen harrier while a straight edge leaves them totally exposed.

The sun was low over the horizon as the male hen harrier crossed the River Ribble and flew up into the Forest of Bowland. Smoke from heather burning was still drifting across the moors and fells, with men in lines tending the edge of the fire. He turned sharply to avoid them, as last year he’d lost three primary feathers to a shotgun blast. He flew straight to one of his favourite hunting areas, an open area of fell well covered with grass. He saw the occasional sheep grazing contentedly, but they took no notice of him. Eventually he found what he was looking for, a marshy area from which sprang a rill that eventually fed into the Ribble. He dropped down until he was about ten to fifteen feet off the ground and began a methodical search for prey into the wind. Flap, flap, flap, glide.

At the end of the marshy area he turned and drifted down with the wind, a V-shaped silhouette that hovered now and then to investigate a movement or a sound. By the rill were several stands of rushes. He heard a squeak and hovered over it, his ears hidden behind the owl-like mask of his face picking up the rustle of movement through the rushes. He extended his long yellow legs, closed his wings and dropped down. His eight black, needle-sharp talons unerringly grabbed the prey, a short-tailed field vole.

Short-tailed field voles thrive in any patch of land or field where there is rough, tussocky grass. Mainly nocturnal, their presence is indicated by holes in grass tussocks where they nest, runs in the grass with holes where they pop up from time to time and remains of grass clippings that they have chewed. Both male and female field voles mark their territory and defend it with splashes of urine. It is estimated that there are 75 million field voles in the British Isles, and their breeding season starts in April or May, continuing through to September or October. A succession of litters is produced, with an average litter size of five, and young born at the start of the breeding season will themselves breed later in the same year. Their breeding success follows a cyclical pattern, a poor year followed by a better one. Then, either in the third or fourth year, there is a peak breeding season. This cyclical pattern is exploited by predators in the good years and has a depressing effect on their productivity during lean periods. Research has shown that peak vole years influence hen harrier numbers, with bigger clutch sizes and number of chicks fledged. Small mammals make up a modest but important part of the hen harrier’s diet throughout the year, and two voles would meet the daily prey requirement of a harrier.

Volume 3 of The Handbook of British Birds, 2nd edition, which I bought as a young boy in 1944, gives a concise list of birds’ prey items. The handbook states that the hen harrier:

preys chiefly on birds and mammals taken by surprise on the ground. Mammals include young rabbits, leveret, mice, field- and water voles, rats, etc. Birds: frequently Meadow-Pipits, Sky-Larks, or young Lapwings; occasionally chicken or duck, Teal, Red Grouse, Partridge, Golden Plover, Snipe, Dunlin: also finches (Linnet, Chaffinch, Snow-Bunting), Song-Thrush, Blackbird, Ring-Ouzel and Stonechat. Snakes (Adder), lizards, slow-worm, frogs, etc., also taken, and eggs or young of ground-nesting birds (Meadow-Pipit, Dunlin, etc.): small fish also once recorded: also Coleoptera.

Eagles, Hawks and Falcons of the World by Leslie Brown and Dean Amadon, published in 1968, tackles the subject from a different perspective. The authors cite one analysis that gives the hen harrier diet as 25 per cent birds, 55 per cent mammals and 29 per cent snakes, frogs and insects. Another nesting analysis gives 31 per cent birds and 69 per cent mammals, with meadow mice predominating. Brown and Amadon state that the hen harrier can occasionally take mammals up to the size of a rabbit, and birds up to the size of a young bittern, but large birds such as ducks are usually wounded or moribund when taken. Food is usually taken on the ground, as the hen harrier can rarely capture birds in the air. Food requirements vary from 100 grams daily for a female (19 per cent of body weight) in cold weather to 42 grams (12 per cent of body weight) for a male in warm weather, the maximum daily intake by a female being 142 grams in cold weather.

Some of the more unlikely species that hen harriers have tackled include hedgehogs and adders, and apart from red grouse hen harriers have been known to take ptarmigan, black grouse, partridge and pheasant. Intra-guild predation has accounted for merlin and kestrel . . . and lastly, an unlucky short-eared owl.