Nature Conservation. Peter Marren

Чтение книги онлайн.

      About 14 per cent of our moss and liverwort flora is considered vulnerable, endangered or extinct. This is JNCC’s projection of their respective ‘threat status’. (JNCC)

      The losers – Mead’s unhappy faces – include familiar farmland birds such as skylark, song thrush, linnet, grey partridge, lapwing and snipe. Even starling and house sparrow have declined markedly. The problem they all face is lack of food on today’s intensively managed, autumn-sown cereal fields. The red-backed shrike has ceased to breed, and the red light is showing for black grouse and capercaillie, which are finding life difficult in the overgrazed moors and upland woods (and no good just putting up deer fences: the capercaillie crashes straight into them). Interestingly, small birds are faring worse, on balance, than big ones. A birder of the 1960s would be shocked at what has happened to lapwings or golden plovers, but pleased and probably surprised at how well many comparatively rare species have adapted to a changing environment. Stranger things lie just ahead. Try imagining green parakeets stealing the food you left out for the disappearing starlings.

      Like birds, some of the smaller mammals have declined more than the big ones. Some carnivores, such as polecat and pine marten, are more widespread today than they were in 1966. The grey seal is much more numerous, thanks entirely to the cessation of regular culling. Deer are also more numerous, though this is a mixed blessing. Though increasing, the red deer is threatened genetically by hybridisation with the increasing, introduced sika deer, and may soon be lost as a purebred species. Bats, as a class, have declined. The best counted species, the greater horseshoe bat, is believed to have declined by 90 per cent during the twentieth century. The present population is estimated to be only 4,000 adult individuals. Only 12 colonies produce over ten young per year (Harris 1993). Rabbits have made a slow recovery from myxomatosis, and are back to about 40 per cent of their original abundance, but occur more patchily than before. The otter has staged a slow recovery, aided by reintroductions, but may take another century to recover its former range across eastern Britain. The real losers are red squirrel and water vole, both victims of introduced mammals. Dormouse and harvest mouse are also declining, apparently because of changes in woodland and agricultural land that reduce food availability. Our rare ‘herpetiles’ (i.e. reptiles and amphibians), sand lizard, smooth snake and natterjack toad, have benefited from site-based conservation and a zealous British Herpetological Society. Most of our freshwater fish seem fairly resilient, but the burbot has been lost and our two migratory shads reduced to rarity status because of pollution and tidal barrages. The char, which likes clear, cold water, has disappeared from some former sites. The powan faces an uncertain future in Loch Lomond following the accidental introduction of a competitor, the ruffe, which eats its eggs. Its relative, the pollan of Lough Neagh, is now threatened by carp, casually introduced nearby to please a few anglers. In the sea, we, with the help of our European friends, have overfished herring, cod and 22 other species, and almost wiped out the skate.

      We should not, however, judge the success of nature conservation measures solely by changes in the numbers of well-known animals. Birds are important, because everyone likes them, and because losses and gains among such well-recorded species are important clues to what is happening to their environment. In nature conservation, every bird is a miner’s canary. But birds are almost too popular. In the 1960s, many field naturalists specialised in relatively obscure orders, pond and shore life, and difficult insects, such as beetles or bugs. Today, an oft-heard complaint is that taxonomists are an ageing and diminishing band, and that the few professional ones are nowadays tied up in administrative tasks. The number of people who can identify protozoa, or diatoms, or worms is probably fewer now than a century ago. As a result, we have no idea what is happening to them. All too often, biodiversity has been lost from ignorance, even on nature reserves. Britain’s nature reserves are run by people who would know a hawk from a handsaw at a thousand paces, but to whom invertebrates are just wriggly things that live in bushes.

      Discovering where the wildlife is

      In the 1960s, the study of British natural history was in a reasonably healthy state, better in some respects than it is today. Entomology and microscopy were less popular than in their late Victorian heyday, but with the advent of cheap, lightweight binoculars, birdwatching was growing in popularity, and ecology was being taught at schools and universities. Serious naturalists were making connections between a species and its environment, which led, by extension, to conserving and managing natural habitats. Naturalists were well catered for by a wide range of books in print, not least by 40-odd volumes in the New Naturalist library. The now universal field guide had made an appearance, but there were also handbooks on beetles, spiders, bugs, grasshoppers and even centipedes and rotifers, at affordable prices. Naturalists were not infrequently equipped with a hand lens, and specimen collecting was not yet considered a crime. Television natural history had begun, with programmes such as Look and Survival and, though still in black-and-white, had less manic, less dumbed-down presenters and they were more often about wildlife near at home.

      Much less was known about wildlife habitats and sites. Although some places had been thoroughly explored by naturalists, with long typed lists of species bound in massive ledgers, there had been few systematic surveys of habitats or species. The first attempts to census and record the distribution of species had been made in the 1920s and 1930s for certain colonial birds, such as heron and rook. However, the most important mapping scheme to date had been for wild flowers. In 1962, the Botanical Society of the British Isles published the Atlas of British Flora, which mapped the nationwide distribution of some 1,400 native or naturalised wild flowers and ferns using dot-maps based on a grid of 10 x 10 kilometre squares. What made the atlas possible was the invention of punch-card computers. СКАЧАТЬ