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Britain Needs More Holes

National Nest Box Week 2019

As part of National Nest Box Week 2019, which kicks off on 14 February, the British Trust for Ornithology (BTO) is calling for homeowners to put up more nest boxes for declining garden birds like House Sparrow and Starling. To support homeowners in doing this, the Trust has produced a new ‘essential guide’, full of useful information on i) what to look for when buying a nest box, ii) box placement and iii) looking after a box longer term. The free guide is available from gbw@bto.org or by calling the BTO’s Garden Ecology Team on 01842-750050.


The simple act of putting up a nest box can make a real difference for our birds, providing them with the space they need to raise a family.

A growing proportion of the global human population now lives in towns and cities, with the United Nations predicting that by 2050 two-thirds of us will live within such urbanised landscapes. 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.

Newly urbanised landscapes often lack the mature trees that provide nesting cavities for small birds, such as Blue Tit and Great Tit, while other cavity-nesting species - such as Starling, Swift and House Sparrow - have seen changes in building regulations reducing nesting opportunities that once existed under the roof tiles of our houses. The loss of such sites may have played an important role in the significant declines seen in the breeding populations of these species since the early 1990s (Starling -74%, House Sparrow -35%, Swift -51%).


Rob Jaques, part of the BTO’s Garden Ecology Team, commented: Homeowners can provide new nesting opportunities for birds by putting up suitable nest boxes and now is the ideal time to do this. You can either purchase a nest box or build your own, and there is plenty of information in our free guide, from cutting plans through to information on where to place nest boxes.

Five things to look for when purchasing a nest box:

The box should be constructed from timber that is at least 15 mm thick.

The size of the entrance hole should be at least 25 mm in diameter. Hole size determines which species will use a nest box. Blue Tit and Coal Tit favour 25 mm, Great Tit and Tree Sparrow favour 28 mm, House Sparrow favours 32 mm and Starling favours a larger box with an entrance hole diameter of 45 mm.

Avoid nest boxes with perches; small birds don’t need these and they may provide a foothold for a predatory squirrel or weasel.

The nest box should be accessible, allowing you to lift the lid or remove the side at the end of the breeding season in order to clean the box out. Boxes may be cleaned out between 1st September and 31st January.

Don’t buy a nest box where the entrance hole is less than 12 cm above the base, since a cat may be able to reach in and grab chicks if the distance is less than this

Paul Stancliffe BTO

5th February 2019