Woodland birds on route to extinction as numbers dive

Birds of Britain's woodlands are declining so rapidly that some appear to be on the road to extinction, a study reveals today.

A suite of woodland species, from the nightingale to the spotted flycatcher, fell by more than 50 per cent between 1994 and last year, according to the report of the annual Breeding Bird Survey, run by the British Trust for Ornithology, the Royal Society for the Protection of Birds and the Joint Nature Conservation Committee. The willow tit has declined by 77 per cent over the period and is extinct over much of Britain. But other declines are nearly as bad: since 1994, wood warbler has declined by 67 per cent, nightingale by 60 per cent, spotted flycatcher by 59 per cent and pied flycatcher by 54 per cent. Lesser spotted woodpecker has declined so much that it is too rare to monitor accurately on a national basis.

Over the past 30 years declines of Britain's farmland birds have been the main concern, with grey partridge and corn bunting falling nearly 90 per cent because of the intensification of agriculture. Now woodland birds seem to be going the same way – but the causes are much less obvious.

Factors being considered include predation by grey squirrels or great spotted woodpeckers (not proved), the decline in the form of woodland management known as coppicing (possible) and the huge rise in the numbers of deer (much more likely). Virtually all species of deer are steadily increasing, led by the muntjac. Their browsing is causing structural changes to the vegetation, and the undergrowth where birds nests are disappearing.

The other factor is migration. Four of the five birds with the biggest drop in numbers - wood warbler, nightingale and the two flycatchers – are summer visitors, spending the winter in Africa south of the Sahara, and conservationists fear trouble on their journeys or on the wintering grounds could be to blame.

The possibility is increased when the picture is widened beyond woodland birds to all species. Of the 10 greatest declines recorded between 1994 and 2007, eight concern long-distance migrants – the other four species being turtle dove (down 66 per cent), yellow wagtail (47 per cent), swift (41 per cent) and cuckoo (37 per cent.) "There may be trouble on migration or on the wintering grounds, such as drought in the Sahel [the region south of the Sahara], but we don't actually know," said Kate Risely, the Breeding Bird Survey national organiser. "We are starting to do more research to try and find out."

But over the same period, nearly all of Britain's more familiar garden birds showed substantial increases, probably reflecting the popularity of garden feeding and warmer winters. Great tit was up 55 per cent, followed by goldfinch (39); greenfinch (27); wren (25); dunnock (25); blackbird (24); robin (21); coal tit (19); song thrush (18); blue tit (14) and chaffinch (also 14). Only house sparrow bucked the trend, down 10 per cent, which reflects its mysterious disappearance from many urban areas.

Other significant rises include raven (up 134 per cent) and buzzard (up 56 per cent), both species now spreading as persecution by gamekeepers declines.