The British household garden is playing a much bigger role in the conservation of wild bird species than was thought.
Blue tit numbers are highest (RSPB-images/Chris Knights)
A study by the British Trust for Ornithology says gardeners can make a difference by making space for birds.
The report has said wildlife friendly gardening is important for the future of threatened species like the song thrush and spotted flycatchers.
Also, a study by the Game Conservancy Trust has said that the endangered grey partridge population has risen.
Britain's gardens cover an area more than twice the size of all the country's nature reserves.
The report by the British Trust for Ornithology (BTO) has said the garden's role in providing a haven for wild birds is equally as important, and millions of pairs of birds have chosen to nest in Britain.
The study is made up of information taken from 6,000 gardens, and ornithologists have produced new figures for the number of pairs of different species nesting in domestic properties.
The blue tit came top, followed by the house sparrow, the blackbird, the great tit, the starling and the robin - all these species had between one and three million pairs each.
The BTO's findings show that species like the song thrush and spotted flycatchers have been declining rapidly in the wild. But the concentration of nesting birds is as high in built-up areas as it is in woodlands.
The estimate for the song thrush nesting in gardens was 300,000 pairs, up 100,000 on a previous estimate.
Richard Bland, one of the report's authors, said: "If all of the gardens in Britain were as bird-friendly as those surveyed, the total number of pairs of birds that would be nesting nationwide could be 30 million.
"That's not bad when national surveys have shown there are only some 60 million pairs of birds in Britain - and that's everything from puffins to pigeons."
The survey by the Game Conservancy Trust is also good news for a bird species that had plummeted in the 1950s and 1960s because of intensive farming.
In 1911 it was estimated that there were a million pairs of breeding grey partridges, but by the early 1990s weed killers and modern crop methods had taken their toll.
Song thrush numbers have significantly increased in Britain's gardens
About 145,000 pairs were left and monitoring has suggested that numbers have halved in the last decade.
The trust says the grey partridge has managed to boost its population numbers because of careful management of the birds' habitat.
A project in Hertfordshire has shown that leaving wild edges to intensively cultivated fields, and creating patches where the birds can forage, have been a significant help.
But a spokesman for the BTO has said the long term population trend for the grey partridge is still downwards.