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BTO National Nest Box Week

National Nest Box Week


8th February 2023

Last Updated: 25th September 2023

With bird breeding season drawing ever closer, you’ll likely have begun to hear your garden birds being much more active. Being the busiest time of year for our feathered friends, it’s more important than ever to provide both food and a safe place to nest.

As part of National Nest Box Week, the British Trust for Ornithology (BTO) is asking us to put up more nest boxes for declining garden birds like house sparrows and starlings. The simple act of providing a home can make a real difference for our birds, providing them with the space they need to raise a family. At Ark WIldlife, we sell a range of high-quality bird next boxes for garden birds, such as our house sparrow nest boxes.

What is National Nest Box Week?

The National Nest Box Week (NNBW) is an established part of the ornithological calendar, taking place from the 14th – 21st of February every year. NNBW encourages people to put a nest box up in their local area. People are also asked to sign up for the Nest Box Challenge, where they can report activity in their nest box. The main aim is to promote and enhance biodiversity and conservation of our breeding birds and wildlife.

Valentine’s Day is traditionally more for birds than humans! The first mention of it as a romantic celebration was in Chaucer’s 14th century poem, The Parliament of Fowls, where he imagined it to be a day when birds gather to choose their mates under the supervision of nature. So, mid-February is the ideal time to start looking out for nesting birds. You could put up nest boxes for tits in search of nesting holes and open boxes for blackbirds and robins.

Why are bird nest boxes important?

Putting up nest boxes during NNBW can provide a nesting site for our treasured garden birds, many of which are struggling after extreme and unpredictable weather conditions. With the total number of birds on the decline and the decrease in the number of available safe places to nest, birds are having a particularly tough time. Providing nest boxes can help by offering good quality, warm, dry and safe homes for growing families in the next breeding season.

An increasing proportion of people now live in towns and cities. Urbanisation is considered to be one of the greatest threats facing birds, resulting in the loss of natural habitats and the feeding and nesting opportunities associated with them. With cleaner, more stripped-back environments, natural holes, nooks and crannies are lacking, meaning birds have fewer places to nest. The loss of these sites may have played an important role in the significant decline in these species since the early 1990s. The Common Bird Census between 1970 and 1999 revealed some shocking insights into bird declines. Some of the most endangered species include the turtle dove, cuckoos and starlings. We can help these birds by providing food, water and shelter, to encourage breeding.

Declines in breeding bird graph
Data and graph provided by the BTO/JNCC/RSPB Breeding Bird Survey

A recent study into the modernisation of urban buildings found that the loss of nesting sites in older buildings can lead to significant declines:

Decrease in bird nests in modernised houses

All birds that lived in the building decreased by at least 60%. The study then provided nest boxes in the modernised building which saw the bird population levels recover by 50%. This demonstrates the power of nest boxes and the difference they make to our bird populations. Providing a safe place to live and breed is essential to maintaining and supporting our feathered friends.

Rob Jaques, a member of the BTO’s Garden Ecology Team, said, ‘Homeowners can provide new nesting opportunities for birds by putting up suitable nest boxes and now is the ideal time to do this.’

How can i get involved with National Nest Box Week?

Helping garden birds during the breeding season is as simple as hanging a nest box in your garden to provide a safe, warm and dry environment for nesting birds. Whether it’s in your own garden, at school or with your local wildlife group – providing nest boxes will attract a wider diversity of birds.

We recommend supplying multiple nesting boxes with different entrance sizes to attract different species:

Nest Box Entrance SizeBird Species
26mm hole– Blue tits
– Marsh and coal tits
– Wrens
32mm hole– Great, marsh and coal tits
– Redstart
– Nuthatch
– Pied flycatcher
– House and tree sparrows
35mm open entrance– Wrens
– Blue, coal and marsh tits
75mm open entrance– Robins
– Flycatchers
– Blackbirds
– Wagtails
115mm open entrance– Flycatchers
– Robins
– Blackbirds
– Wagtails
32mm Sparrow Terrace triple fronted
entrance holes
– House sparrows 
– Great and blue tits

We can also help by monitoring nest box activity. Providing this data to the BTO is vital when it comes to conservation efforts and understanding the state of the UK’s bird population. You can submit data to BTO through one of two surveys – Nesting Neighbours or the Nest Record Scheme. This data is compiled and helps produce annual estimates.

When should I put up a nest box?

You can put up a nest box at any time of year but autumn and early winter tend to be the best times. Birds can start looking for a nesting site as early as January. But not to worry! National Nest Box Week is the perfect reminder to place your nest box in early February, as breeding season tends to begin in the middle of the month.

Nest box top tips

Getting involved in National Nest Box Week is incredibly fulfilling, giving you the opportunity to make a real difference to local garden birds. To make the biggest impact, have a read of some of our top tips:

  • Nest boxes should be made from an insulating material such as wood to ensure they stay warm and dry.
  • Don’t place your nest box in direct sunlight as it can overheat.
  • Avoid nest boxes with perches as these allow predators to access the interior.
  • Place your nest box at least 1.5m above the ground.
  • Clean out any existing nest boxes prior to breeding season.

For more information, read our comprehensive guide on siting bird nest boxes.