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Keep nest boxes simple, not stylish, says RSPB

Last modified: 19 February 2016

Male house sparrow in young willows

Image: Graham Catley

With BTO’s National Nest Box Week (14-21st February) upon us and spring time fast approaching, people across the UK are being urged to dust off their muddy wellies and get back into the garden to put up a nest box in time for the bird breeding season. 


Boxes shaped like caravans, farmhouses, eggs and even windmills are on sale as nesting sites for garden birds, but the RSPB is warning people that attractive and elaborate bird boxes are not necessarily safe or effective for nesting birds and, in some cases, unsuitable nest boxes could lead to birds being put in danger.


The charity is asking people to avoid purchasing or making these potentially dangerously designed bird boxes and instead ensure they choose the right shape, size and material of nest box.
Although some nest boxes might look like a quirky feature in your garden, they could actually be dangerous for young birds for a number of reasons.


Materials and designs that might look attractive, such as ceramics and bright colours, are completely unsuitable for nesting birds as they’re poorly insulated and do not make the box inconspicuous to predators.


Nest boxes with metal roofs retain too much heat and can have fatal effects for baby birds on warm, sunny days. Metal and plastic nest boxes also suffer from condensation causing baby birds to get damp and cold.


Ben Andrew, RSPB Wildlife Advisor, said: “It’s crucial that people put up nest boxes to help our garden birds, especially those in decline like house sparrows and starlings.
“Rather than choosing unusual designs and materials, people should stick to traditional, wooden nest boxes; they really are the best and often the most cost effective.
“It’s also really important to make sure boxes are sited in the correct place. This depends on the species the box is intended for but there’s lots of information on our website.
“People tend to forget that a nest box will eventually contain tiny helpless, vulnerable baby birds so the appearance of the box should be the last thing on your mind.”


The RSPB is offering advice on what is suitable and what’s not with some nest box dos and don’ts:


They should:
- Be robust – they are out in all weather and need to be strong and fit for purpose
- Be waterproof – they need to be treated with a water-based preservative
- Have the correct hole-size – if too large predators will easily get inside and rain/wind will get into the box
- Be safe – no dangerous sharp edges, protruding nails or staples or unnecessary fixtures or small gaps which may harm or trap birds
-Have good insulation – wood or woodcrete is usually the best material
- Have no perches


They should not:
-          Be brightly coloured – the more inconspicuous the better
-          Be made from flimsy material – many boxes fall apart when any weight is put inside
-          Be too shallow – young birds could leave prematurely by falling out
-          Be too deep - young birds may have problems getting out when they are ready
-          Be too smooth on the inside – slippery material will also make it difficult for young birds to get out
-          Have gaps – rain and cold air will get in and cause young birds to get cold and damp

Carl Barimore, Nest Records Organiser at the BTO, said, "Now in its 19th year, National Nest Box Week is about providing suitable nest sites for birds in our gardens and green spaces. This means taking simple precautions to make sure nest boxes are built correctly and put up in the right places so they are safe for their occupants. Looking after nesting birds also means collecting data on how well they are doing, so we encourage people to monitor their boxes and tell the BTO what they see."


Some of our best loved garden birds are losing their natural nest sites fast which is thought to be one of the reasons for the alarming decline in birds such as house sparrow and starling over recent years. At the end of last month thousands of people took part in the Big Garden Birdwatch where they spent an hour counting the birds they saw in their garden. The charity will reveal the latest highs and lows for birds and other wildlife in March when the results from the survey are released.


For more advice and a step-to-step guide on making your own nest box visit www.rspb.org.uk/makeahomeforwildlife. A variety of tried and tested nest boxes, including the new sparrow terrace nest box, are also available to buy on the RSPB’s online shop at www.rspbshop.co.uk.

How you can help

Nature in the UK is in trouble and some of our more familiar garden species are amongst those suffering serious declines. We can all help by giving nature a home where we live.