From 1 October to 31 March Natuurpunt collects and compiles the results of the bird counts by a number of volunteers.
They send information every month regarding the species of birds that come to their gardens and their numbers.
Apart from the monthly information from volunteers a national Bird Counting Weekend is held once a year.
That is what is taking place this weekend.
And how does this work?
After having replenished the feeder you count how many birds come during a period of 30 minutes. Per species, they write down the largest number in the garden at a given moment.
According to Natuurpunt you do not have to be an expert to count the birds in your garden.
On the Natuurpunt website there are photos of the most common birds in Belgium so you can recognise the type of birds you have in your garden.
Several dailies also periodically include posters with the most common birds in Belgium.
Last year 450 people were involved in the monthly counting. More than 6,600 took part in last year's national Bird Counting Weekend. Some 290,000 birds were counted last year.
The information compiled by Natuurpunt is clearly not scientific, but it gives an idea of the trend from year to year.
Last winter was the coldest winter since the counting started and the result was that there were spectacularly more species of birds than in the previous winters. This winter is also much colder and Natuurpunt expects a wide variety of birds to be counted this weekend again.