WHICH bird will be crowned Cornwall's number one feathered visitor to gardens this winter? It is the 25th anniversary of the RSPB's Big Garden Birdwatch and everyone's chance in Camborne and Redruth to take part in the world's biggest survey of its kind.

Since 1979, the first year Big Garden Birdwatch took place, the RSPB has seen national participation rise from 30,000 to a record-breaking 314,000 in 2003 with 4,843 people surveying 3,151 gardens in Cornwall. The county's number one bird was the house sparrow

The survey has provided some very useful information on the state of garden birds. Although many birds are doing well, there are some areas of concern.

Alarmingly, the RSPB has seen the average number of starlings in gardens plummet from 15 to just four and house sparrow numbers more than halve from ten to four. Song thrush numbers have also fallen sharply, dropping out of the top ten. All three of these species have now been declared birds of high conservation concern.

Big Garden Birdwatch takes place every year during the last weekend of January and aims to find the most commonly seen garden birds. Bird watchers do not have to be an expert to take part and it is a fun event designed for all the family.

People are being asked to spend one hour counting the birds in their garden or local park, and record the highest number of each bird species seen at any one time. The morning is the best time to look, when the birds are active feeding after a cold winter night.

Tony Whitehead, Big Garden Birdwatch co-ordinator, said: "It's an incredible achievement for a survey to reach its 25th anniversary. We are amazed at how the popularity of Big Garden Birdwatch has grown over the years. I hope we'll attract even more people in Cornwall to take part in this year's survey, helping us to celebrate 25 years of birdwatching fun."

There is a serious side to Big Garden Birdwatch. Numbers of many familiar garden birds are falling. This survey alone has seen starling numbers drop by 67 per cent and house sparrow numbers by 52 per cent in the last 25 years, which shows surveys like Big Garden Birdwatch can provide vital information.