I'm Winterwatch ornithologist Jack Baddams and this is why feeding birds might be doing more harm than good

This article first appeared in Radio Times magazine.

I’ve fed the birds for as long as I can remember, and I’m not alone. We love seeing birds on our windowsills and balconies and in our gardens, and want to help them. In the UK, it’s estimated that every year 17 million households spend £250 million, collectively, on bird food.

There is, however, growing chatter among conservationists about whether feeding the birds is all it’s cracked up to be. It’s an issue we’ll address on this year’s Winterwatch – might we be doing more harm than good?

One of the biggest concerns is that bird feeders spread disease, sometimes with devastating consequences. In 2005, the disease trichomonosis made the jump from pigeons to greenfinches after they shared feeding stations. The greenfinch population crashed by 62 per cent and the species is now on the red list.

Their close cousin, the chaffinch, is suffering a similar fate, with almost 40 per cent disappearing in just 11 years. The RSPB has stopped selling bird tables and other flat-surface feeders while it awaits the outcome of a review into the issue.

We should also consider the staggering quantity of food we leave out for birds. In the UK we buy more than 150,000 tons of bird food every year. Where does it all come from? Bird food is farmed, like any other crop. The ground is worked and often sprayed with chemicals to suppress native plants that might compete. Some of our favourite bird food, like peanuts, is grown in warm climates and so shipped here from around the world.

A third issue is the ecological effect of all that bird food. Does feeding favour all birds equally? Some of our garden bird populations are thriving, with 40 per cent more great tits and 152 per cent more goldfinches than 30 years ago. Other populations, though, like that of the pied flycatcher, are plummeting.

After flying to Africa for winter, the pied flycatchers should return to UK woodlands to find that the colder months have knocked back numbers of some of their nest-hole competitors, like blue tits and great tits. With a constant supply of bird food, however, competitor populations have risen, while theirs – which doesn’t benefit from feeders, as they prefer insects – has decreased by 38 per cent in three decades.

Scientists are working to increase our understanding of how feeding might alter bird populations, but it appears that we could also be changing birds’ bodies. A study into the beak lengths of great tits found that British birds’ bills are becoming longer. The researchers’ best guess as to why this change is happening is that they’re evolving a longer beak to help them get food from bird feeders.

We’ve all been encouraged to feed the birds for years, including by us on Winterwatch, where this year we’ll feature red squirrels, pine martens, badgers and songbirds at our new base of Mount Stewart, a National Trust estate in County Down. But if feeding might be more problematic than we thought, what can we do instead to help birds get through the winter?

You can bring them to your garden or balcony with plants that produce berries, nuts and seeds. Replicate nature as best as you can, in whatever outdoor space you’ve got to work with. Sunflowers are a great option, providing nectar for insects in the summer and tasty seeds when the flowers have finished.

Plant native bushes and trees, like oak, birch, guelder rose or hawthorn, that provide home for lots of insects for birds to eat, or make a pond that will catapult the biodiversity in your garden through the roof.

Put simply, when it comes to helping our feathered friends, think about how you can build an ecosystem, not just a fast-food restaurant.

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Winterwatch returns at 7pm on Tuesday 20 January on BBC Two and iPlayer.

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