ON A WING AND A PRAYER

Over the last year or so, anyone with more than a passing interest in wildlife will not have missed the media coverage about the decline and fall of our once abundant farmland birds.

Skylarks for instance, have declined by 58 per cent over the last 25 years, a loss of 3m birds. Grey partridges are down by 82 per cent; tree sparrow numbers have fallen by 89 per cent. They are staggering reductions, caused by the intensification of agriculture since the Fifties. With flower and insect-rich fields ploughed up, wetlands drained, hedgerows uprooted and crops sprayed with selective herbicides and insecticides, there is now little habitat in which they can eke out an existence.

But all is not ornithological doom and gloom. While around 100 of Britain's breeding birds have declined overall between 1800 and today, 130 species have increased or held their own. And, although 20 species are in steep decline, 18 are increasing rapidly. Even more surprising is that we have 36 more species of breeding bird today than in 1800. Less than a third of these have been released or escaped from captivity; the majority arrived naturally, have found our countryside to their liking, and have settled down.

These statistics come from a unique analysis by Dr David Gibbons and Dr Mark Avery of the RSPB working with Dr Andrew Brown of English Nature and published in British Birds. They used a scoring system to assess the general population trend of each species that bred in Britain between 1800 and the present, pulling together information from previous estimates of populations and what was happening to them.

Why 1800? Simply because there are few reliable accounts going back further. The oldest systematic census in Britain dates from 1928 when a yearly count of nesting herons began. More recently, the first nationwide, systematic census - begun in 1962 - is the Common Birds Census (CBC), organised by the British Trust for Ornithology and carried out by an army of volunteers to a standard method.

The CBC - recently replaced by the Breeding Bird Survey - required a series of visits to defined plots of land in which the breeding territories of birds were marked on maps. The results, collated for the whole of Britain, provided the basis for monitoring population trends. It's from this date that we know about the severe falls in farmland birds.

The Breeding Bird Survey (BBS) requires fewer site visits but gives better habitat and geographical coverage so that trends in the populations of individual species can more easily be understood. It has been running since 1994. Britain's top 20 breeding-bird league (see box) is based on its 1995 results, the most recently analysed.

Conservationists of the future will have one of the most comprehensive data banks anywhere in the world upon which to base judgements about what is happening to Britain's birds. Positioned as they are towards, or at the top of food chains, breeding-bird populations can be a reliable index of the general state of our countryside. If, for instance, barn owls are on the increase, it is reasonable to assume that populations of small birds and small mammals - mice, voles and shrews - are also increasing, along with the lowland habitats of hedgerows, marsh and flowery meadows that provide them with a home.

There are now 230 bird species that breed in Britain compared with 194 in 1800. Most of this increase has occurred since 1940. Nine of the new species are introductions, unintentional or otherwise, according to Dr Gibbons and his co-researchers. One example is the mandarin duck. Kept since 1747 as an ornamental bird, the first releases into the wild were made around 1900 by the Duke of Bedford. Today there are nearly 4,000 mandarins in central and southern England, exceeding the number in all the Orient, excluding Japan.

The common pheasant, let loose here by the Romans or in the early Middle Ages, is, to say the least, an introduced bird with a long pedigree. But two other species, the golden pheasant - first released in the wild in the 1880s - and the showy Lady Amherst's pheasant - introduced in the 1890s - are more recent arrivals which have established themselves in parts of eastern England. The other introductions since 1900 are the wood duck, red-crested pochard, ruddy duck, rose-ringed parakeet, little owl and the domesticated rock dove.

The other new species - 27 of them - have arrived here naturally. They include the elegant crane, now a rare breeder in East Anglia where it hadn't been seen since the 17th century; the little ringed plover, a shingle- breeding wading bird which arrived in 1938 and now numbers perhaps 1,000 pairs; and the noisy, little brown and cream Cetti's warbler, which made its debut in the 1960s and now numbers perhaps 500 pairs breeding in dense scrub in parts of southern England and Wales.

Dr Gibbons and his colleagues examine the reasons for such a hike in bird species in their analysis, concluding that improved protection, more positive attitudes towards wildlife, and better care taken of key habitats and sites all play a part. So, too, do the sheer numbers of today's bird watchers. The chances of a new species arriving here and hoping to go unnoticed are slim.

"I think that better habitat management by conservation organisations and landowners plays an important role; birds arrive by chance but then they stay," comments Dr Leo Batten, a leading ornithologist working for English Nature. "Species have colonised here from different directions, so there is no overall climatic trend. It may be that climate warming is helping a few species such as Cetti's warbler (a Mediterranean species) survive here," he adds.

By attributing positive (for increasing abundance) or negative scores (for decreasing abundance) from zero for no obvious change to plus or minus five for a substantial increase or fall, the researchers have compiled a pattern for each species in five time periods from 1800 to 1995. Several of the species with the highest positive scores over the two centuries increased most between 1800 and 1939 and have since slowed.

The tufted duck is a good example. It first bred in 1849 and spread rapidly to colonise most suitable lakes. By 1940- 1969 its spread and increase in numbers, had slowed; between 1970 and 1995 it had stabilised in Scotland and was increasing very slowly elsewhere.

Some species, here in 1800, have since gone. The great bustard, a turkey- sized land bird, last bred in 1832, a victim of land enclosure, agricultural intensification and hunting. The great auk, a large, penguin-like bird, was once found on some of the Scottish islands. Persecuted to the end, the last Scottish bird was beaten to death on St Kilda in 1821. It is extinct worldwide.

For others, birds of prey in particular, long declines - mainly at the hands of gamekeepers and landowners - have been slowed, even reversed, in recent years. Greater tolerance coupled with legal protection, the banning of the most poisonous pesticides, and some restoration of previously damaged or destroyed habitats have all helped.

The red kite, for instance, an impressive, red-brown, bird of prey with a forked tail, was a common street scavenger in Chaucer's London. Persecution reduced it to a handful of pairs in west Wales by early this century. Conservation efforts have turned the tide. This year, 150 pairs bred in Wales. Introductions in England and Scotland have resulted in around 50 pairs breeding, creating the prospect of it regaining its rightful place in the countryside.

Although the new analysis shows that 102 bird species have declined overall between 1800 and today, the number falls to 82 if those showing an increase in recent decades are removed from the statistics. They include birds of prey such as the sparrowhawk, buzzard and osprey plus others like the perky Dartford warbler of southern heaths, the woodland and garden jay, and the seacliff-breeding guillemot.

It is difficult, though, to be overly positive, especially about farmland birds. More intensive farming ousted the corncrake, a noisy but secretive haymeadow and cornfield bird once commonplace across Britain. Now confined to the Hebrides and Orkney, expensive conservation programmes have bolstered numbers from an all-time low of 480 singing males to 564 this year. Other birds of the farm - the corn bunting, yellowhammer, turtle dove and skylark - are plummeting too.

But should we be so concerned about farmland birds when the fields and hedgerows so reminiscent of some bucolic idyll are entirely man-made. Until Roman times and the early Middle Ages, extensive forests clothed much of Britain and wetlands filled many a lowland valley. If we took a perspective longer than a couple of centuries, we would not be bothered about skylarks, the numbers of which must have shot up as forests were felled. Long term, it is woodland and wetland birds which have crashed in numbers: woodpeckers, tits, nightingales and thrushes; tree-hugging species such as nuthatches; and the snipe, bitterns and herons of the marshes.

Dr Mark Avery, one of the study's authors and the RSPB's head of research, agrees. "But," he says, "Re-creating woodland and wetland habitats is a major, longer-term investment. The recent declines in common, farmland birds is so big and rapid; relatively small changes in the way farmland is managed would halt the decline and boost their numbers again."

Britain's birds, their abundance and distribution, are a litmus test for the state of our countryside. We know more about how they are faring than we do for any other group of plants or animals. No longer can there be a case for ignorance of the consequences of how we steward this land of ours. !

WATCH THE BIRDIE

BRITAIN'S MOST ABUNDANT BREEDING BIRDS

Starling

Wood pigeon

House sparrow

Blackbird

Chaffinch

Wren

Carrion crow

Blue tit

Jackdaw

Robin

Skylark

Swallow

Greenfinch

Linnet

Magpie

Great tit

Willow warbler

Dunnock

Pheasant

Song thrush

Source: 1995 Breeding Bird Survey run by the British Trust for Ornithology, the RSPB and the Joint Nature Conservation Committee