The number of birds visiting our gardens and parks has plunged, a survey has revealed.

The decline follows a succession of mild winters and the growing popularity of paving and decking.

The latest figures from the Royal Society for the Protection of Birds come from its annual Big Garden Birdwatch in January, when more than 960 Brighton residents spent an hour counting birds in their gardens and local parks.

The survey showed that the starling remains the city's most common garden visitor, followed by the house sparrow and then the blue tit.

However, numbers have fallen dramatically in four years.

In 2005 an average of 7.17 starlings, 5.4 house sparrows and 2.47 blue tits were spotted per garden in an hour.

This year birdwatchers recorded averages of just 3.46, 3.14 and 1.89 in an hour.

During mild winters, birds are able to find the nuts and seeds they need in the wild, and so do not have to stray into gardens.

The trend for decking robs gardens of valuable plants and insects.

An RSPB spokesman said: "If you don't have as much grass and plants, then you won't see as many birds."

Changes in farming techniques, a decline in hedgerows and increased used of pesticides may also have hit bird numbers.

But while there have been losers, some species that might normally shun our shores are attracted by the warmer conditions.

Four species of colourful finch - siskins, bramblings, redpolls and goldfinches - are making increasing visits to Sussex gardens while in Brighton and Hove the chaffinch ranked eighth - its first appearance in the top ten.

Dr Andrew Farrar of the RSPB said: 'It's definitely been a good winter for finches.

'The figures suggest that tree seed supplies have been poor this year and they've been forced into gardens to find food.' Hester Phillips, from RSPB South East, said: "The survey findings help us to understand more about the population trends of garden birds.

"We predicted that last year's terrible weather would be reflected by the Big Garden Birdwatch and this seems to be the case, especially for blue tits.

"A snapshot of winter only gives part of the picture but this year's results also suggest a further fall in sparrow numbers in some areas.

"Our gardens can be very welcoming to finches, especially where people put out food and provide a wildlife area where thistles and teasels are left to grow which also provide food."

Would you welcome more diverse and colourful birds attracted by global warming - or would it be an environmental disaster?