Valentine’s Day may mean that love is in the air for some of us humans. But it is also the time of year when many birds in the UK start to think seriously about the coming breeding season. As well as performing courtship rituals and starting to hang around together in obvious pairs, they will also begin looking for the perfect place to rear their chicks. So, it is appropriate that as well as Valentine’s Day, February 14th is the start of National Nestbox Week. Running since 1997, this campaign aims to highlight the increasing importance of nestboxes. There are also lots of resources explaining how to get involved. But why do we need to put up nestboxes? And how do we go about choosing the right boxes and locations?
Replacing Lost Nest Sites
Many of our bird species use some sort of hole or cavity to build their nests in. These kinds of spaces, after all, offer protection from both predators and the worst of the elements, whether heat, cold, wind or rain. Sadly, though, birds are finding it increasingly difficult to find suitable nest sites due to a number of reasons. Much of this is down to habitat loss as we develop and remove more of our natural spaces. As climate change increases the likelihood of extreme weather events, we are also seeing more frequent and severe storms. These can bring down large numbers of trees, consequently removing many nest options. It is estimated that storms during the winter of 2021/22, for example, felled over 8 million trees across the UK. Since the Second World War, we have also lost 50% of our hedgerows, another vital nesting habitat. And many hedgerows that survive are in too poor condition to provide safe cover for nesting birds, as well.
Changes to the way we construct and maintain our buildings also impacts nest availability. Many bird species, including house sparrows, starlings and swifts, take advantage of holes and spaces in our buildings to nest. But as we become more determined to make our homes as air-tight and sealed as possible, these opportunities are removed. Swifts, in particular, now struggle to find suitable holes to nest in, having long ago abandoned more natural settings such as tree holes and caves. We also increasingly tidy our outdoor spaces, removing ivy and older trees, for instance, that are also good nest sites. However, by putting up nestboxes, we can help to replace these lost nesting opportunities.
Choosing a Nestbox
So, if you want to get involved and help your local bird populations, how do you go about it? The first thing to do is to decide what sort of nestbox or nestboxes you want to put up. You may have an idea of what species you want to attract, and which are present in your local area. As different birds prefer different nesting sites, this is probably a good place to start when it comes to choosing a box. Blue, great and coal tits, along with rarer species like pied flycatcher and redstart, prefer closed boxes with smaller access holes. Robins, spotted flycatchers and pied wagtails, meanwhile, like open-fronted nestboxes. Swifts have more specialist requirements and need fairly large boxes with an oblong access hole. Swallows and house martins use cup-shaped fittings that can be attached under a house’s eaves. House and tree sparrows like communal nest sites, so a sparrow terrace is a good idea. The National Nestbox Week site has a nice visual guide to who prefers what. If you decide to make your own nestbox instead of buying one, the BTO has some good information on constructing a number of box styles.
Materials are also important, whether you are making your own box or buying one. Good quality wood or woodcrete (a blend of wood fibres with cement and clay), provide durability and protection from both high and low temperatures, as well as predators. Plastic, metal or poor-quality wood, on the other hand, will expose eggs and chicks to extreme cold or heat, plus are unlikely to keep predators out. You might also want to provide extra protection to a closed nestbox with a metal plate round the entrance hole. This helps prevent any predators from enlarging the hole to get in the box. Likewise, if the box comes with a perch, remove it as they aren’t necessary and can potentially aid unwanted access. Choose a nestbox with a sloping roof and an overhang above the entrance hole so that rain runs off easily and is less likely to enter the nestbox. A hinged roof can also help you access and clean the box more easily once the breeding season is over. Ventilation and drainage holes are also essential to ensure temperature regulation and allow moisture to escape.
Where and When to Put Up a Nestbox
Choosing your nestbox site is also important. Boxes should be facing away from direct sunlight and with some shade so as not to get too warm. They should also face in a different direction from the prevailing winds to give them some shelter in stormier weather. Make sure there is a clear flight line to the box and that it is away from any overhanging branches so that predators don’t have a helpful nearby perch. Provide some cover around open-fronted boxes, though. If you have bird feeders up, don’t site your nestbox in the same area. Feeding stations can be competitive and noisy places, so not ideal neighbours for a young family. All that activity can act as an advertisement to predators, as well, thereby attracting them to any nearby nestboxes. As a general rule of thumb, fix your nestbox at least a metre from the ground. Some species have more specific requirements. For example, while house sparrows like to nest communally, tit species tend to be quite aggressive to each other, so their nestboxes need to be further apart.
Now is the perfect time to install a nestbox, if you haven’t already. Although some birds will already have been nest prospecting earlier in the winter, most will start from February onwards. By installing now, you give your neighbourhood birds the best chance of finding your box before the breeding season gets into full swing. Remember that birds can be wary of change, however, so it may be that no one uses your nestbox the first year it is up. If it hasn’t been used within two or three years, consider moving it to another spot. It might be that there was something about its position that put prospective nesters off. You should empty and clean your nestboxes annually but only once the breeding season is over. By law, you are only allowed to do this between September 1st and 31st January. Even when it gets to September, though, you should make sure there are no late broods being raised before removing a nestbox to clean it. Some species, such as wrens and tits, use nestboxes as winter roosts in cold weather, too, so try and complete any maintenance before any very cold conditions set in.
A Boost for Birds
As well as physically providing birds with safe breeding sites, nestboxes can benefit them indirectly, too. If you live in the UK, you can sign up to the BTO’s Nesting Neighbours scheme and help provide them with valuable data. This citizen science project is free and easy to join and involves monitoring any nestboxes, or indeed any other nests, in your garden. The scheme asks you to check the progress of active nests once a week during the breeding season and send in details of nest-building activity, eggs laid and chicks reared over the spring and summer. To avoid the risk of any nests failing, you must follow the BTO’s Code of Conduct, however. In particular, although you are asked to look carefully in your nestbox each week, never touch any eggs or chicks inside without a licence. Remember that the birds’ welfare is always of paramount importance.
The data you send back helps researchers accumulate important information about how birds are faring and why populations might be changing. This in turn can inform conservation efforts. As we continue to lose vital habitat in the UK, gardens are becoming ever more important for wildlife. As such, we can learn a lot from the birds and animals that increasingly use them. And we benefit, too. By providing birds with nesting options and attracting more to your garden, you are getting closer to nature. Research shows that connecting with nature is hugely beneficial for our mental wellbeing. It is very much a win for everyone involved. So, this National Nestbox Week, why not put up your own nestboxes and help your avian neighbours?