Garden birds: international travellers or staycationers?

There’s a point coming up very soon when, should you step outside on a clear night, you are very likely to hear the soft but insistent tseee calls of migrating Redwings as they pass overhead.

Later in the winter if conditions turn harsh, you are then likely to see some venture into gardens looking for berries and windfalls. And given that barely a handful of redwings breed in the UK up in the wilds of Scotland, you know that they are all likely to be international migrants from Scandinavia and beyond.

But what of your other garden birds in winter? How do you know if they are local birds (the ones you’ve been seeing through the summer), or incomers from distant lands, or indeed a mix of the two?

Well, decades of bird ringing have given us the answers that otherwise would be nigh on impossible to tell. These bird ringers are dedicated folk, working under licence, putting up fine mist nets to catch the birds, quickly wrapping tiny numbered metal rings around their right leg, and setting them free again. With luck, the ringed birds will then turn up in another net somewhere else, giving us a clear picture of how far they have moved (even if we don’t know what mischief they've got up to in between).

The results are summarised in a chunky tome called The Migration Atlas produced by the BTO, which gives us a window on the lives of birds, including those in our gardens. Here is my headline interpretation of the data for some of our most familiar species.

Robin, Blackbird and Song Thrush:

For all three species, those that breed in our gardens are unlikely to ever move very far. Some may disperse after breeding, but only locally. For example, only 4% of British-bred Blackbirds move more than 20km, and most move less than 1km. The Robin is the same. In Song Thrushes, birds from northern Britain are a little more likely to move further, probably to escape the worst of the winters, but then head back where they came from.

However, large numbers of Continental birds of all three species migrate through the UK in autumn, coming from the Low Countries, northern Germany and Scandinavia. But most are on their way further south, leapfrogging our resident populations.

So those you see in your gardens are almost certainly familiar faces.

Blue Tit and Great Tit:

These two species are interesting in that adults tend to stick close to their breeding territories all year, but youngsters born this year do like to have a bit of a wander. I can’t claim that they are mega adventurous – by September, for example, 95% of young Blue Tits are still within 28km of their birthplace.

But it is as if these two birds put on their teenage backpacks and go exploring their home county. Don’t worry, by the next breeding season, most of those young Blue and Great Tits will be back within earshot of where they were born.

Goldfinch:

Ah, now here’s a bird with a bit of a difference. On the one hand, some are just like the other birds already mentioned which stick very close to where they hatched. However, quite a few head south, often all the way down to Spain and Portugal for the winter, returning in spring. And it seems that this isn’t hardwired into them – some years an individual bird may staycation in the UK, sticking to lockdown; in other years it may spread its wings for a winter break in the Med.

Chaffinch:

Half of the Chaffinch population wintering in the UK are visitors from the Continent. However, what we don’t know for sure is how many of these venture into gardens to mix with our home-bred Chaffinches, which in contrast are very sedentary.

In fact, there is evidence that Chaffinches from abroad tend to form large flocks out in the wider countryside, so those in your garden may indeed still be mainly your local birds. Yes, yet another case showing how those birds that breed in our gardens love them so much that they just stay put!

Starling:

And you know what, the theme continues with our Starlings, with those that are British bred seeming to be homeboys and homegirls, very faithful to where they were born. To travel more than a few kilometres would be unusual.

But our home-grown birds are then joined by mass flocks from all the European countries around the North and Baltic Seas, and it seems very likely that these happily intermingle with our own Starlings.

So, your flock of Starlings at your feeders could be a happy melting pot of British, German, Polish and Danish birds, all mucking in together.  

So, wrapping it all up…

As you can see, the picture is clearly one in which many of the birds in your garden in winter are likely to be the same faces you saw in summer. If you have one of those gardens where bird numbers build up in winter, well, they probably bred nearby. They’re locals.

But among them, especially if the weather turns a bit hard, may be a few glamourpusses: the Redwings, Fieldfares and Blackcaps plus some European Starlings to add some Continental flavour to the amazing melting pot of life in gardens.