How was your garden over the weekend? Was it full of birds, attracted in by the food provided in hanging feeders, scattered on the ground or placed on your bird table? In many thousands of gardens across the country, householders will have spent some time watching the birds and recording their observations for the RSPB’s Big Garden BirdWatch (see www.rspb.org.uk). This once-a-year, mass participation project is a fantastic example of how to get people engaged with their garden birds and the concept of ‘citizen science’.
So, how was your garden over the weekend? Did you notice more coal tits and siskins than you would normally see; did you have more birds visiting because of the weather or because you’d topped your bird feeders up in preparation for the weekend? There’s a lot of subtlety to the patterns seen in garden use by birds. The numbers visiting are not simply related to population size but are strongly influenced by weather, food availability and where your garden is located. This year, for example, we know that coal tits have increased their use of gardens, starting last autumn, because the 2012 conifer seed crop was so poor. The same is true for siskin (another conifer specialist) but, since this species only turns to gardens in big numbers from late January, we can make the prediction now that you will see increasing numbers of these birds over the weeks ahead.
The failure of other tree seed crops and the poor showing of autumn berries might see other birds increase their use of gardens this winter, although some – notably the thrushes – may have pushed further south into France and Spain to seek more favourable conditions there. Freezing temperatures elsewhere on the Continent, will have been behind the movements into Britain of other thrushes over the last two weeks, so it is a very dynamic picture. What is clear, however, is that what you will have been seeing in your garden reflects what has been happening at a much wider spatial scale.
You might wonder how we know that coal tits increased their use of gardens last autumn, that late January is when the siskins arrive or that there have been fewer thrushes in gardens over the early part of the winter? Well, it’s all down to another group of citizen scientists, those who take part in the BTO’s weekly Garden BirdWatch survey (see www.bto.org/gbw). By charting what they have seen on a weekly basis, these citizen scientists have delivered a wealth of information on how the use of gardens by birds (and other wildlife) varies throughout the year and in relation to other factors, like seed crops, weather and local habitat; all very useful stuff.