FAQs about nest boxes

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See below some of the questions we get asked about nest boxes. If you need more help nnbw [at] bto [dot] org

How high should my nest box be?

The ideal height for a small-hole type nest box is between 1m and 5m above the ground with a clear flight path. Care must be given to make sure the box isn’t easily accessible to predators.

Can I put my nest box on the side of my house?

Yes, a nest box with a 32mm entrance hole fixed on the wall of a house could well be used by House Sparrows. For Starlings try a box with a 45mm entrance hole.

How big should the nest box hole be?

Bird

Nest box hole size

Blue Tit

25mm

Great Tit

28mm

Tree Sparrow

28mm

House Sparrow

32mm

Can I look inside my nest box?

Yes, provided you approach quietly and carefully, it is perfectly safe to look into a nest box from time to time to see how things are progressing once the birds are incubating their eggs. Most birds will sit very tight on their nest if you just peek in, though an early morning visit may find the bird off her nest in search of a quick meal before nest duties call her back. This is a good time to count the number of eggs in the nest and to record this information as part of Nest Box Challenge.

Should I clean out the nest box?

When the breeding season is over, old nests can be removed and the box cleaned out. Bird Protection Law permits the cleaning out of nests between 1 August and 31 January. Any dead eggs must be destroyed promptly and cannot be kept or sold.

Some hole-nesting species, including sparrows, may have second or third broods in the same nest. The nests of these species should be left until sometime during the autumn when it is certain that they are no longer in use.

When cleaning out nest boxes it is advisable to wear surgical gloves and a dust mask. Old nests may harbour fungi growing on damp nest material, which can cause respiratory diseases. Nests can also house a variety of parasites such as fleas, lice and ticks. It is best, therefore, when removing the old nest to put this straight into a plastic bag and seal it before disposal.

My nest box has never been used...

You can increase the probability of a box being used by choosing a suitable location. However, there are lots of factors that could be stopping birds using your nest box such as the presence of natural nesting areas nearby.

Welsh language NNBW information

Download Welsh-language National Nest Box Week information

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If you can't find the information you're seeking about nest boxes in the above list then nnbw [at] bto [dot] org.