Why are we counting birds?
To understand why we're asking you to count birds, we need to rewind the clock and start at the beginning!
It's 1979 and we're looking for a simple winter activity that our junior membership can get involved in. As it's likely to be cold and the evenings dark, we think a weekend activity in the garden would be best.
So, we asked our members to count the birds in their gardens, all at the same time, so we could work out the UK top ten most common garden birds.
Biddy Baxter - the editor of Blue Peter at the time - liked the idea so much that she featured the survey on one of the programmes. We had only expected a few hundred children to take part, but thanks to Biddy's coverage, we actually got over 34,000 forms!
And that's how our 'one-off' activity grew into the regular event it is today. Although it wasn't until 2001 that we invited adults to join in the fun, too.
Find out more about the history of the world's biggest wildlife survey as Gemma Butlin, RSPB Media Manager, talks to Peter Holden, the creator of Big Garden Birdwatch:
How you've already helped
For over 30 years, we've been asking you to count the birds in your garden – and you've been brilliant at it.
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 to our scientists.
With results from so many gardens, we are able to create a 'snapshot' of bird numbers across the UK. Let's take a look at some of the population changes you've helped us see. All changes are from 1979 to 2012:
Blue tit numbers have increased by 20% from 1979 to 2012
We've lost two-thirds of our house sparrows
Robins have suffered a population decline of 32%
Starlings have suffered one of the steepest declines (80%) of any bird in our survey
Woodpigeon numbers have increased a massive 800%
While these changes can seem scary - we've lost more than half our house sparrows and some three-quarters of our starlings - it isn't all doom and gloom.
Your results help us spot problems, but more importantly, they are also the first step in putting things right. And this is why it's so important that we count the garden birds.
The more people involved, the more we can learn, so please encourage your family, friends and neighbours to take part.