The RSPB Big Garden Birdwatch aims to provide the charity with valuable information about the numbers of birds visiting gardens in the winter.
More than half a million people are expected to take part in this year’s event, which is regarded as the world’s largest garden wildlife survey.
Daniel Hayhow, RSPB conservation scientist, said: “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.
“As the format of the survey has stayed the same, the scientific data can be compared year-on-year, making your results very valuable.
“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 survey is now in its 37th year and takes place on January 30 and 31.
Previous figures show a continuing decline in the number of starlings and song thrushes, which have dropped by 80 and 70pc since the bird watch began in 1979.
The house sparrow is the most commonly spotted bird in people’s gardens, but its numbers have dropped by 57pc since 1979.
People taking part in the survey are also being asked to log other wildlife found in their gardens.
Hedgehogs, foxes stoats and squirrels can all be recorded to help build an overall picture as to how important gardens are to animals.
Mr Hayhow added: “The threats to our wildlife means that it’s facing tough times. For example 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.”
How you can take part
To take part you will need to spend one hour at any time over the Big Garden Birdwatch weekend recording the maximum number of each bird species you see at any one time.
People are also asked to jot down any other types of wildlife in the garden, such as hedgehogs, foxes, stoats and squirrels.
All you need to do to take part is grab a cuppa and position yourself comfortably in front of a window with a good view of your garden.
People without a garden can head to a local park to carry on bird watching there.
To sign up for your free Big Garden Birdwatch 2016 pack and to submit your results, visit www.rspb.org.uk/birdwatch.
Students are also being encouraged to take part in the Big Schools Birdwatch from January 4 to February 12. More information can be found at rspb.org.uk/schoolswatch.