Features: Homes for garden animals

Making a nest box for hole nesting birds

You must choose a nest box design that is suited to the type of birds you wish to attract. This feature describes how to make a wooden nest box suitable for small hole nesters like blue tits and sparrows.

Selecting your materials

Its easiest to build this kind of box from a plank of wood rather than a sheet - it reduces the amount of cutting you will need to do. Rough sawn timber is cheaper and actually better for this job (birds can grip it better). Buy untreated timber - its both cheaper and better for the birds.

This box can be made using timber ranging from about 15 by 150mm to about 25 by 175mm. The smaller size is suitable for tits and the larger is big enough for house sparrows. The box described here used timber bought as 7 by 1 inch, but in fact its actual dimensions were 20 by 175mm.

Marking out and cutting the wood

Measurements marked with an asterisk vary a bit depending upon the thickness of the wood. An angled cut should be used at point A. All measurements are in millimetres. Mark your plank up as shown here. Some of the dimensions may vary slightly depending on the thickness of the wood you are using - the aim is to get a flush fit between the sloping roof and both the front and back of the box.

The entrance hole can be difficult to make. An electric drill with a specialist hole cutter is best, but you can use a coping saw or a router if you have one. The size of the hole is important because that will determine what types of bird will be able to use the box. A hole with a diameter of 25mm will allow blue tits and coal tits to use the box, but prevent larger birds like great tits and house sparrows from entering. A diameter of 28mm is large enough for great tits and you must go up to 32mm if you want to allow house sparrows to use the box.

There should be at least one small hole in the base of the box to allow rain water and waste produced by the birds to drain out of the box, but I also take a small amount of wood off the corners.

Assembling the box

I find it easiest to assemble the pieces by first attaching the sides to the front and then the base. This assembly can then be offered up to the middle of the back piece and the roof fitted last of all by means of a hinge.

Putting it all together

38mm panel pins, angled towards each other, join the wood.

Here a hinge was made of some shed roofing felt.

A catch for the roof made from two screws and some stiff wire.

Use panel pins to join the wood - they are quite narrow and are less likely to split the wood than thicker nails. A pin every 3 or 4cm should be sufficient to make a robust nest box. Attach the roof of the box using a hinge to allow you to open it for cleaning. Some old roofing felt or rubber from an old bike inner tube, can be used for the hinge.

Finishing off

The finished box. Don't use preservatives inside the box - its not good for the birds. You can finish the outside of the box with preservative if you want (but not too close to the hole) but its not necessary. If you like, you can fix a special metal guard to the hole to keep out predators.

Hanging the box

You should site the box so that it faces away from the prevailing wind and rain and where it will not be in direct sunlight for much of the day. You can hang the box on a wall or in a tree at least six foot off the ground. It must be out of the reach of cats. Hang your box at any time of year. Note that birds might take several seasons to get used to it. Always remember too that it could be used by birds and other animals in winter.

Aftercare

Around September or October you should inspect the box and remove any nesting material or other debris which you find there. You can then add some clean straw (don't pack it too tight) to make the box attractive as a winter roosting box for small birds. Up to 60 wrens have been seen leaving a single nest box after very cold winter nights! In the spring, around early March, clear the box out again ready for the nesting season, perhaps just leaving a little straw in the bottom of the box.