RSPB: keep nest boxes simple

An English Starling's home is its castle – but try not to make its nest box too ornate. Photo: Mark Thomas (www.rspb-images.com).
An English Starling's home is its castle – but try not to make its nest box too ornate. Photo: Mark Thomas (www.rspb-images.com).
As National Nest Box Week comes to an end, the RSPB has offered advice for putting up boxes.

With spring time fast approaching, people across Britain 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 breeding season, and to contribute to this year's British Trust for Ornithology National Nest Box Week (14-21 February), which finishes this weekend. 

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 elaborate bird boxes are not necessarily safe or effective for nesting birds. In some cases unsuitable nest boxes could even lead to birds being put in danger.

The wildlife charity is asking people to avoid buying or making these potentially dangerous bird boxes, and trying to ensure that they choose the right shape, size and material. 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 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 heat and can have fatal effects for chicks on sunny days; metal and plastic nest boxes also retain condensation causing baby birds to get damp and cold.

RSPB Wildlife Advisor Ben Andrew said: “It’s crucial that people put up nest boxes to help our garden birds, especially those in decline like House Sparrow and Starling.

"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 has also offered some nest box dos and don’ts:

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

They should not:
• be brightly coloured – the more inconspicuous the better
• be made from flimsy material, as many boxes fall apart when weight is put inside
• be too shallow, as young birds could leave prematurely by falling out
• be too deep, as young birds may have problems getting out when they are ready to fledge
• be too smooth on the inside, as slippery material will also make it difficult for young birds to get out
• have gaps, as 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: "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."

For more advice and a step-to-step guide on making your own nest box visit www.rspb.org.uk/makeahomeforwildlife.
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