The world's largest garden wildlife survey, now in its 37th year, takes place on 30 and 31 January 2016. Since it began it has provided valuable information about the changes in numbers of birds using UK gardens in winter.
Continuing declines include starlings and song thrushes, which have dropped by 80 per cent and 70 per cent respectively since the event began in 1979.
There is slightly better news for the house sparrow, as its long term decline appears to have continued to slow, and it remains the most commonly spotted bird in UK gardens. However, its numbers have dropped by 57 per cent since 1979.
Daniel Hayhow, RSPB conservation scientist said: "Last year's survey saw more than 8.5m birds spotted, making it another great year for participation. With over half a million people now regularly taking part, coupled with over 30 years' worth of data, Big Garden Birdwatch allows us to monitor trends and helps us understand how birds are doing."
The format of the survey has stayed the same so the scientific data can be compared year-on-year, making the results very valuable, he added.
"With results from so many gardens, we are able to create a 'snapshot' of bird numbers across the UK. Once we know which birds are in trouble, together we can ensure that our garden wildlife will be around forever."
The RSPB is also asking participants to log other wildlife, including hedgehogs, foxes, stoats and squirrels, to help build an overall picture of how important gardens are for giving nature a home.
Hayhow explained: "It is estimated that we've lost more than half of our hedgehogs in the last 50 years. We're going to include this part of the survey every year now, enabling us to monitor the distribution of our other wildlife as well as trends in bird numbers."
The survey is part of the RSPB's Giving Nature a Home campaign, aimed at tackling the housing crisis facing the UK's threatened wildlife. The RSPB is asking people to provide a place for wildlife in their own gardens and outside spaces.