Most bird boxes are made of wood and will be fine when hung up in their natural state, as untreated, unpainted wood most closely resembles birds’ natural nesting environments.
However, as pressure-treated wood is not recommended for bird box construction you may choose to paint yours to help preserve it and extend its life. A painted bird box can also make an interesting feature in your garden.
Unpainted hardwood bird houses, such as those made from cedar or cypress will withstand the weather quite well and can last for up to 15 years. But softwood bird house made of pine or plywood can rot quickly in wet weather and so may last longer with a coat of paint.
Pressure-treated wood is produced by forcing chemical preservatives into the wood. The preservatives penetrate deep into the timber which makes it more durable and able to withstand damage and exposure to the elements.
Wood treated in this way is low maintenance and ideal for decking, fences and garden furniture and most outdoor wooden structures.
Pressure-treated wood can also be treated with fungicides and pesticides and although there is no conclusive evidence that the residual fumes from the treatment can harm wild birds it is recommended that nest boxes are constructed from untreated wood.
If you are buying or making a nest box the best woods to use are hardwoods such as oak, beech, or cedar. Look for wood that is between 1.5 an 2 cm thick to give the birds the insulation they need to keep warm.
Birds aren’t too fussy about their accommodation and will be quite happy to nest in a painted bird box. It can be fun to paint a bird box so it resembles a real home or even a pub or a caravan, but be aware that your handiwork may not always be admired or appreciated by wild birds, and a novelty bird house may even put your garden birds at risk.
A very brightly coloured bird box could be conspicuous to predators or it might put off birds from using it altogether who may choose to use more natural looking sites nearby. Dark coloured bird boxes will absorb heat and the temperature inside could rise to dangerous levels on warmer days, either suffocating the chicks inside or encouraging the growth of toxic bacteria. Choose light colours that will reflect the heat, and position your bird house in a shady spot if possible.
The best colours to use are muted, natural colours that blend into the surroundings of your garden. Brown, greens, or greys are ideal if your box is hidden amongst foliage, or you could paint it to match the fence or wall you secure it to. If your bird box is going to be sited amongst flowers you may want to pick brighter colours. Whatever you choose, avoid metallic, fluorescent, or iridescent paints that may contain harmful additives.
Make sure you use a water-based latex paint and avoid lead-based paints or creosote that are toxic to both birds and other wildlife. Try using eco-friendly, organic paints and stains that are kind to the environment and kind to birds.
Don’t paint inside the box or around the entrance hole as birds may peck at it and ingest chips of paint. Clear film finishes such as shellac, varnish, or lacquer shouldn’t be used as sunlight and moisture will cause them to crack, blister, and peel.
Once you have painted your bird box leave it to dry thoroughly for a few days before hanging it up. This will mean any potentially toxic fumes have time to disperse. You should ideally paint a bird box at the end of the summer which will allow enough time for the paint to fully cure before the next spring.
When cleaning your nest box at the end of each breeding season check the paint and if it is peeling or has chipped sand it down and repaint it if necessary. This will help keep your bird house in good condition so it lasts longer.
As long as you choose your paints and colours carefully a well-painted bird box can provide an attractive home for birds that they will be more than happy to move into and raise their chicks in.