If you go down to the woods today, you may not be guaranteed to see too many birds but you could well bump into a census-taking birdwatcher. The Biological Records Centre celebrated its 50th anniversary this summer and citizen science flourishes in Britain as never before. If one needs proof, look no further than the proliferation of published bird atlases, in which every single scrap of data has been sourced from the fields and woods by volunteers and then donated freely to the atlas editors. The resulting books are among the most compelling statements of our nation’s amateur fixation with nature.

Since 2011, around 20 such works have gone to press, covering counties or regions as diverse as Greater London and Clackmannanshire. They span the country from Sussex to Aberdeen and Argyll. They culminated recently in the largest-ever nationwide stocktake of our avian populations by the British Trust for Ornithology (BTO), Bird Atlas 2007-2011 (£69.99). Indeed, it is the field census efforts undertaken by the BTO’s army of volunteers that have, in many cases, catalysed the recent slew of regional and county-based works.

Individual fieldworkers, monitoring their local birds in selected two-kilometre squares (known in atlas parlance as “tetrads”), have been able, because of new data-processing software, to contribute to the national overview and to the finer-grain regional picture. Between them, the tens of thousands of observers have assembled an astonishing 19 million records. In the process, they have made Britain’s birds the most thoroughly documented avifauna on the planet.

Yet the story they reveal is deeply troubling. Never before have we known in so much detail how badly some of our birds are faring. The grey partridge, which was once found nationwide and whose overall numbers were calculated in seven figures, has sunk towards national extinction. Today, there may be fewer than 75,000 pairs and the decline continues.

The BTO’s national atlas may give us the bigger picture but it is in the many new regional works that one truly sees the impact of change on the ground. Andrew Self’s The Birds of London (Bloomsbury, £50), for example, reveals how grey partridges were once all over the capital, including areas such as Dulwich, Kew, Chiswick and Wormwood Scrubs. Then began the bird’s inexorable vanishing act. Self’s last report is of just three pairs in west London and even these are thought to be individuals released from captivity.

The picture is much the same in The Breeding Birds of North Wales (Liverpool University Press, £45), edited by Anne Brenchley, Geoff Gibbs, Rhion Pritchard and Ian M Spence. Grey partridges once occurred in almost every lowland parish and only the more austere Snowdonian uplands were without them. By 2012, however, the editors could pinpoint the four tetrads where the bird was still proven to breed. Most of the map is blank.

Even more compelling is the equivalent account of the lapwings of north Wales. These beautiful waders, whose cartwheeling song displays were once a quintessential part of rural life, have a particular association with the grass pastures used for grazing livestock. So the sheep-flecked hills of Cymru were once lapwing heaven. Not now. The atlas editors estimate a breeding total of just 600 pairs in more than 6,000 square kilometres of what was once their primary habitat.

It is when the regional atlas dials down the focus to look at specific places that you start to unearth the real effects of the developments. In the lapwing account in the hugely detailed and beautifully produced The Birds of Derbyshire (Liverpool University Press, £45), the book’s editors, Roy Frost and Steve Shaw, tell us of a spot called Calton Pastures near Bakewell. This small place may have held lapwings for 2,000 years and in 1976 there were still 39 nesting pairs at Calton. By 1981, numbers were down to eight or nine pairs. Twelve years later, there were none at all.

I can testify to how such change affects both place and human occupant, because I grew up in Buxton, ten miles from the lapwing pastures near Bakewell. The songs of lapwings were the soundtrack to my childhood. During the 1970s, I recorded all the local birds almost daily. In the intervening 40 years, I have monitored the gradual disappearance of an entire breeding community: grey partridge, lapwing, redshank, snipe, dunlin, woodcock, common sandpiper, cuckoo, ring ouzel, wheatear, whinchat, common redstart, wood warbler, tree pipit and twite. All of these birds once bred near my family house. All have gone.

The Birds of Derbyshire documents the wider and slow-failing fortunes of this avian suite, which is part of the fabric of the northern uplands, yet the book cannot conjure the sense of personal loss. For me now to revisit Buxton is to encounter a landscape of ghosts.

There are also positive developments reflected in The Birds of Derbyshire. One of the most heartening is the resurrection of our birds of prey following centuries of human persecution and the subsequent crisis triggered by organochlorine pesticides. In the 1960s, raptors such as the peregrine were thought to be at risk of global extinction. Today, however, there are probably more peregrines in Britain than at any time since the early-modern period.

In Derbyshire, the birds are now widespread, and a pair routinely nests on Derby Cathedral. Andrew Self notes a similar churchgoing habit in London, with peregrines haunting St Paul’s and Westminster Abbey. This falcon’s return reflects that of other birds of prey: marsh harriers and red kites, common buzzards and hobbies, even rarities such as the white-tailed eagle, goshawk and honey buzzard. All have flourished in an era of greater protection and wider tolerance from game shooters.

A second good news story is that the numbers of many wetland birds have either remained stable or, in some cases, vastly risen. In recent decades, the human demand for drinking water and construction materials – which has given rise to reservoirs and gravel pits – has supplemented the deliberate creation of aquatic habitats by environmental organisations. Some of the results have been spectacular. The avocet, for instance, the symbol of the Royal Society for the Protection of Birds (RSPB), has increased greatly in numbers and spread to a dozen counties.

To the traditional British birds of wet areas such as swans, geese and ducks we may soon have to add a species suite from other parts of the continent. They include a range of herons – great and cattle egrets, purple herons, spoonbills – and also European gems such as the hoopoe and bee-eater. More than a dozen southern birds are predicted to arrive in Britain soon but, even though their exotic presence is much anticipated, they are not a signal for hope.

The northward expansion of Mediterranean inhabitants is clear proof of climate change, which could eventually wreak havoc by shutting down the entire Afro-European migration system. Some of the birds whose loss in the Derbyshire hills I previously lamented – the common sandpiper, cuckoo, ring ouzel, wood warbler, tree pipit and common redstart – will not just decline further. They will cease to come altogether.

When all the increases and losses are taken into account, the overarching picture is one of devastating reduction. In the last decades of the 20th century, 44 million breeding birds vanished from the British countryside. The total avian population has probably never been lower since the last Ice Age. A highly troubling aspect is the pace of change. The north Wales atlas reports that in 2002, local ecologists classified the region’s entire avifauna according to categories of red (27 species), amber (69 species) and green (125 species). This reflected an assumption that more than 60 per cent of all Welsh birds were in a healthy condition. However, in 2010, the list was revised – red was up to 45, amber was up to 100 and green was down to 68 – to reflect the new reality.

Birds are metaphors for landscape not just in an imaginative sense but also at an ecological level. Warm-blooded vertebrates that are high in the food chain, they are the most compelling expressions of an underlying bio-luxuriance, which is rooted in the diversity of invertebrate and vegetative communities. The immense decline in the overall numbers of birds foretells a wider and systemic shrinkage in all natural species. Last year, there was confirmation that the entire countryside is in crisis with the publication of the State of Nature report, compiled by 25 wildlife organisations. Of 3,148 species, 60 per cent were found to be declining and 31 per cent declining strongly.

This presents a challenge in more ways than one. Since the 1980s, successive British governments, following the lead of the Thatcher administration, have withdrawn from the notion of a state-backed policy on nature. Under the present government, the official conservation agency Natural England (along with its counterparts in Wales and Scotland) has been financially emasculated and politically silenced. What became in effect the privatisation of the nature business has left the voluntary sector, represented primarily by the National Trust and the RSPB (with the Wildlife and Woodland Trusts in a secondary role), as the lead players in the wildlife market.

The Herculean achievements of these institutions have moderated the problems of natural loss but they cannot by themselves be a remedy. The National Trust and the RSPB may own or manage 460,000 hectares of some of our richest habitats but that is only 2 per cent of Britain’s land surface. That the RSPB has more members than all the main political parties combined is probably the most frequently cited statistic about the organisation. But the statement rests on a major fallacy: most of these members are not motivated activists. Very often they are just people who like the birds in their gardens. The RSPB’s magazine, now blandly renamed Nature’s Home, is less a political pamphlet than a source of reassurance and a sales brochure. The RSPB and the National Trust may have a combined membership of five million but this does not embolden them; it makes them nervous about their primary asset.

In some ways, they are right to be nervous: research shows that bleak messages of wholesale decline wash poorly with the public. Since the 2008 recession, polls have consistently shown that support for nature conservation has declined, while the perceived need to sacrifice land for economic development has gained in popularity. For much of the public, nature is not a topic for political anxiety. It is a green and pleasant comfort blanket, a sort of immersive therapy to help slough off other social woes – food banks, recession, jihad, the EU, and so on.

The publication of so many detailed bird atlases now leaves the environmental community in a bind. The books’ message about the systemic loss of nature in Britain becomes the truth that dare not speak its name. This much, however, is also certain: if the British are ever going to be able to reverse these losses, then accurate, detailed inventories such as these exemplary works of citizen science will be of central importance.

Mark Cocker’s books include “Birds and People” (Jonathan Cape, £40) and “Birds Britannica” (Chatto & Windus, £35)