Your bird feeders are killing garden birds, warns wildlife expert – do these safety checks NOW!
As Britain’s birds quietly begin their search for somewhere safe to raise the next generation, our homes – gardens, balconies and even walls – have never mattered more. Wildlife expert Kate Macrae explains why nest boxes are now essential, how to get them right, and how a little care can turn any outdoor space into a haven for our garden birds
Britain’s garden birds and the modern housing crisis
On a still February morning, when frost lingers on lawns and the first clear birdsong breaks winter’s hold, many birds are already house-hunting. Not for food, not yet for mates, but for somewhere safe to nest. For generations, birds relied on gaps in old buildings, rough eaves and holes in ageing trees. Today, those spaces are disappearing.
“Our homes are warmer and more efficient than ever but that’s come at a cost for wildlife,” says Kate Macrae, wildlife expert and founder of wildlifekate.co.uk. “Modern buildings are sealed tight, with smooth plastic facades and repaired roofs that leave birds with nowhere to go.”
Dead and decaying trees, once full of natural cavities, are also routinely removed for safety or aesthetic reasons. The result is a national shortage of nesting spaces, hitting cavity-nesting birds hardest.
Nest boxes help to replace what has been lost. They are a small intervention with a big impact – and they offer something else too: a way for us to slow down and notice the natural world just beyond the glass.
Which birds need our help the most?
Many people start with a simple wooden box and are delighted when blue tits or great tits move in – often within days. But beyond these familiar favourites are birds whose decline has been quieter, and far more concerning.
House sparrows, once synonymous with British streets, have declined dramatically, especially in towns and cities. “They’re social birds and love nesting together,” explains Kate. “A sparrow terrace – several boxes grouped together – can make a real difference.”
Starlings, now red-listed in the UK, also depend on cavities in buildings. Slightly larger boxes, mounted high on a house wall, can provide a lifeline.
Perhaps the most urgent case is the swift. These extraordinary birds spend almost their entire lives on the wing, returning each year from Africa to the exact same nesting site. Historically, they slipped under eaves. Today, many of those access points have vanished.
“Swifts are heartbreakingly faithful to their homes,” says Kate. “If that space is blocked, they don’t just find another, they often fail to breed altogether.” Swift boxes and swift bricks, which can be incorporated into new builds, are now considered vital conservation tools.
“If you can help cavity-nesting birds, you really are helping the species that need us most,” says Kate
Photo: Kate Macrae ‘Wildlifekate’ wildlifekate.co.uk
Tree sparrows, marsh tits and willow tits have also suffered from habitat loss and changes in land management. All will use suitable nest boxes, sometimes raising multiple broods in a season.
Even adaptable species like robins and wrens need the right conditions. They favour open-fronted boxes tucked into dense foliage, mimicking the sheltered nooks they naturally seek.
Larger birds face their own challenges. Barn owls have been hit hard by the loss of old barns and quiet lofts, while kestrels and tawny owls depend on large cavities in trees or buildings. Specialist nest boxes can offer a second chance.
You don’t need a big garden
One of the most common myths about nest boxes is that you need lots of space. In reality, birds are remarkably adaptable.
“Putting up a nest box is one of the simplest, most joyful ways to help wildlife – and it brings nature right to your window,” says Kate
“Even the smallest outdoor area can work,” says Kate. “I’ve had blue tits nesting on a balcony wall on a block of flats. If the box is secure and sheltered, they’ll find it.”
Late winter is the ideal time to put boxes up. From February onwards, birds begin prospecting for nest sites. By April, many are already laying eggs.
Position matters more than size. Boxes should be out of direct midday sun and protected from driving rain. A north- or east-facing wall is often ideal, and boxes should be fixed securely, high enough to deter predators.
Video: Kate Macrae ‘Wildlifekate’ wildlifekate.co.uk
What size nest box is best?
Nest box painted in Protek Royal Exterior in Mendip Mist, £3.96 for 125ml sample tin
Photo: protekproducts.co.uk
For most gardens, a traditional rectangular wooden box is perfect. Hole size determines which birds can enter:
- 25mm – blue tits
- 28mm – blue and great tits
- 32mm – sparrows and larger species
Open-fronted boxes suit robins and wrens, while swifts and birds of prey require specialist designs.
Material matters too. “Avoid thin, novelty boxes,” advises Kate. “They offer little insulation and can overheat or become damp.” Solid wood provides protection from temperature extremes and weather.
Technology has added a new layer of connection. Nest box cameras now allow us to watch nesting behaviour live via an app for a Springwatch-style experience at home. Kate live-streams several of her own boxes on her website, including blue tits, nuthatches and even a tawny owl.
“Watching a family of birds grow, from mossy nest to first flight, never gets old,” says Kate
How to look after your nest box
A well-cared-for nest box can last for many years. Treating wood with a wildlife-safe paint or stain protects against damp – one of the main causes of nesting failure.
Kate recommends Protek Royal Exterior, a UK-made paint designed to be safe for wildlife once dry. “I use it inside and out,” she says. “This will prevent damp, which is key, and will make cleaning it easier too. It means the box lasts much longer.”
Photo: Kate Macrae ‘Wildlifekate’ wildlifekate.co.uk
Natural tones are best. Becky Rackstraw, Director at Protek, explains why: “Birds see colour differently to us. They are generally drawn to bright, high-energy and vibrant colours, as their tetrachromatic vision allows them to see UV light, red, green and blue, often with higher acuity than humans. But while they’re drawn to vibrant colours, nesting birds need to feel safe. Greens, browns and greys help boxes blend into their surroundings, whereas even a white box can be alarming.”
“Nesting birds need to feel safe so paint nest boxes in shades of green brown and grey to help them blend into their surroundings,” says Becky
Each autumn, once breeding has finished, boxes should be cleaned. Remove old nesting material, which can harbour mites, then pour boiling water inside and allow the box to dry thoroughly.
“Every year, once cleaned out at the end of the season, I give it my nest boxes a new coat of Protek in my favourite shades of Jungle Green and Forest Green,” says Kate.
There’s no need to add bedding. Birds prefer to build their own nests. You can help by offering natural materials – moss, grass, sheep’s wool or untreated pet hair – placed loosely in feeders or even a kitchen whisk. Avoid anything synthetic and never use pet hair from animals treated with flea products.
Bird feeders are vital, but they can kill
Feeding birds can be invaluable, particularly in winter and during extreme weather but only if it’s done properly.
“Hygiene is absolutely critical,” says Kate. “Dirty feeders spread disease incredibly quickly.” Feeders should be easy to dismantle and cleaned thoroughly at least once a week, with ports and perches wiped daily.
Surface feeding on tables is discouraged. Food becomes damp and mouldy, and wooden surfaces are hard to disinfect. If you do use a flat surface, choose removable dishes that can be cleaned daily.
Photo: Kate Macrae ‘Wildlifekate’ wildlifekate.co.uk
High-quality food matters more than quantity. Sunflower hearts, sunflower seeds, suet pellets and fat balls are excellent energy sources. Peanuts must be offered only in specialist feeders. Mealworms (dried or live) are particularly valuable in spring when adults are feeding chicks.
To keep larger birds and squirrels at bay, Kate mounts feeders inside a repurposed dog crate with a plastic lid – small birds slip through the mesh, while bigger visitors are excluded.
Helping birds through cold and wet weather
Flooding, frost and prolonged cold can be deadly. Nest boxes also double as winter roosts, offering shelter on freezing nights. Supplementary feeding helps birds maintain energy reserves when natural food is scarce.
Fresh water is just as important. A shallow dish, cleaned daily and kept ice-free, can be a lifeline.
“Clean food, clean water and safe shelter – those three things can save lives in winter,” says Kate
Photo: Kate Macrae ‘Wildlifekate’ wildlifekate.co.uk
Common mistakes to avoid
- Feeding bread, which fills birds without nourishing them
- Buying cheap feed full of wheat and fillers
- Leaving feeders dirty, allowing disease to spread
- Offering peanuts loose, which can cause choking
- Placing boxes in direct sun or exposed positions
- Disturbing nests during the breeding season
A simple way to make a real difference
In a world of overwhelming environmental challenges, nest boxes offer something rare: a practical action that genuinely works. They bring birds back into our daily lives and reconnect us with seasonal rhythms that are easy to forget.
Whether it’s a single blue tit box on a balcony or a carefully placed owl box at the edge of a field, every safe space matters. For birds facing a housing crisis of our making, a nest box is not just a feature – it’s a lifeline.
Photo: Kate Macrae ‘Wildlifekate’ wildlifekate.co.uk
National Nest Box Week runs from 14th – 20th February – putting the spotlight on breeding birds and asking everyone to put up more nest boxes in their local area.
Photos: Getty Images
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