What does our warm winter mean for Britain's wildlife? The RSPB reports that it is receiving "endless calls" from people worried about the dwindling numbers of birds. Readers concerned at the absence have flocked to the Telegraph's letters page, casting blame far and wide. Alan Stewardson, a correspondent from Redditch, in Worcestershire, fears the decline of song thrushes in his garden is as a result of magpies stealing the eggs. Another letter writer, Freddie Gee from Harpenden, Hertfordshire, suspects next door's cat for the absence of blackbirds, which each autumn feast on grapes that hang outside his kitchen window. The real problem is, say experts, that normally, at this time of year, the first frosts would have forced birds over picket fences in search of food in Britain's back gardens, the combined acreage of which is bigger than all our national nature reserves put together. Instead, they remain out in parks and open spaces, feasting happily on autumn's lingering fruits. "We run a garden survey through the winter, and people are telling us that activity in their gardens is very quiet," says Paul Stancliffe, from the British Trust for Ornithology. Because it's so mild, birds are not using up as much energy as usual. It's also a really good berry and seed crop this year. There is plenty to eat still out there. They don't need to come into gardens to find food. It is, as Stancliffe says, a paradox. Despite the alarm at their absence, this winter has been the best for birds for a long time. The biting frosts of recent years have claimed many lives, but when the survivors rush to our gardens for something to eat we don't necessarily notice the decline. For decline it is. The State of the UK's Birds report, published last week, shows that of Britain's 107 most widespread and common breeding birds, 16 species have plummeted by more than a third since 1995, including the willow tit, starling, cuckoo, lapwing and wood warbler. The song thrush population has dropped by 56 per cent since 1970. Yellowhammers, those wonderful ruffled farmland birds, have declined by 54 per cent over the same period. As another Telegraph reader, Hamish Grant, from Buckland St Mary, Somerset, says, this is largely as a result of habitat loss. Mr Grant recalls a childhood where hedgerows were so thick one couldn't even count the eggs in a nest. Now they are strimmed to their stumps, he has not seen a yellowhammer for 10 years. The destruction of habitats was also addressed by Sir David Attenborough this week when discussing BBC Radio 4"s Tweet of the Day, a 90-second burst of birdsong that has become the station's most popular segment online since launching this year, and which he is presenting over the festive period. For now, the birds are singing a chorus - though perhaps not in our gardens - that outstrips even Sir David's mellifluous descriptions each morning. But it is a long few months ahead. Soon, winter will bite, the berries will disappear and the birds will retreat to our gardens - and feeders - once again. When we finally start seeing them is, we must remember, when they will need us most.