Building a Bat Box

Bats are becoming increasingly rare in the UK. Loss of roost sites is just one of the reasons for their sad decline. You can help these fascinating little mammals by making new roost sites for them.

Bats may roost in a variety of places - woodpecker holes, buildings, caves, mines and railway and canal tunnels. But old trees are cut down or blown over by strong winds, buildings are often sprayed with deadly woodworm treatment, mine shafts filled in, caves and tunnels disturbed, and the bats are left without suitable roosts. Bat boxes can help by providing alternative roost sites for them.

BUILDING THE BOX
Building a bat box is easy with care. The best wood to use is softwood, as it is cheap and fairly weather resistant. Rough wood is better as this helps bats to get a good grip as they clamber around, inspecting the bat box. If the wood is smooth, rough it up by using the teeth of a saw. For each bat box you will need a plank of wood of the size shown in Fig 1. To complete construction, just follow the remaining diagrams - easy!

There are some important things to remember when making and siting bat boxes:

Do not use any wood preservatives or paint on bat boxes. Bats are sensitive to smells and some chemicals are harmful to bats.

Fixing your bat box with nails may damage the tree so ask the tree owner to attach the box with wire around the trunk or branch. Use a piece of hose or section of car tyre over the wire to prevent damage to the tree. Remember that trees grow, so any fixing should be checked every year.

Place your bat boxes as high up as you can so that they are safe from cats. It is best to put them on trees but you can use the sides of buildings. Three boxes per tree is ideal, facing north, southeast and south-west. Boxes facing in different directions may be used at different times of the year and in varying conditions. Make sure there are no branches around the box - bats like an uncluttered flight path to and from the roost. bat box plans

It is useful to site boxes in places where bats are known to feed but have no nearby roosts. Good sites are near rivers, ponds, woodland glades and sheltered hedgerows. The sides of woodland rides are good places, as are trees that are a little isolated. These trees are easy to spot in urban areas such as parks, schools and hospital grounds.

Don't forget to contact your local bat group to let them know what you are doing. They will be able to offer help and advice.

Never disturb your bat boxes - it is illegal to disturb bats and it is also cruel. The best way to see if they are being used is to look for small, dry, crumbly droppings below the box or for the bats themselves leaving the boxes as night fails. A licensed batworker from your local group may be able to come and inspect them.

Don't worry if you think your bat boxes are not being used immediately. Bats leave little trace and are rarely seen as they move about a lot so they may well be using the box. If you find treecreepers, blue, coal or great tits nesting in your bat box, check the size of your entrance slit it's probably too big.

Noctule Bat

Noctules are the biggest bats in Britain and have a high and straight flightpath. They have long, narrow wings.

Brown long-eared bats can be identified by their huge ears, broad wings and hovering flight. They are rarely seen in flight because they emerge late and fly so close to the leaves of trees.

Daubenton's Bat

Daubenton's bats (above) are medium-sized bats with a white underside. Often, they fly over water like tiny hovercrafts. They have big feet to scoop insects from the surface.

Pipistrelle Bat

The pipistrelle (above) is Britain's smallest species of bat, weighing the same as just 10 paperclips. They look much bigger in flight and have a very erratic flightpath. They are the commonest bat seen in gardens and the most likely to use bat boxes.

REFERENCES AND USEFUL ADDRESSES
Our thanks go to the Robert Stebbings Consultancy and the Bat Conservation Trust for helpful comments on this article. The bat box shown was designed by Bob Stebbings and Sheila Walsh. For further advice on bats, please contact

The Bat Conservation Trust,
15 Cloisters House
8 Battersea Park Road,
London SW8 4BG.
Tel: 0171 627 2629.
or
The Robert Stebbings Consultancy,
74 Alexandra Road,
Peterborough
0E1 3DG
Tel: 01733 340318
They will also be able to tell you how you can contact your local bat group.

There are many good books on bats.
We recommend the following:

Fenton, M B (1992) Bats. Facts on File, London/New York.
Richardson, Phil (1985) Bats. Whittet Books.
Stebbings, Robert (1992) Bats. Mammal Society.
Stebbings, B & Walsh, S (1988) Bat Boxes. FFPS, NCC & The Vincent Wildlife Trust.
Richarz, K & Limbrunner, A (1993) The World of Bats. TFH Publications, Hants.
Altringham, J D (1996) Bats - Biology and Behaviour. Oxford University Press, Oxford.
Hutson, A M (1987) Bats in Houses. The Bat Conservation Trust, London.
Thompson, S (1989) Bats in the Garden. School Garden Company.

RSPB, The Lodge, Sandy, Bedfordshire SG19 2DL.
Telephone 01767 680551.
RSPB Northern Ireland Office, Belvoir Park Forest, Belfast BT8 4QT.
Telephone 01232 491547.
RSPB Scottish Headquarters, 25 Ravelston Terrace, Edinburgh EH4 3TP.
Telephone 0131 311 6500.
RSPB Wales Office, 18 High Street, Newtown, Powys SY16 2NP.
Telephone 01686 626678.

The Royal Society for the Protection of Birds is the charity that takes action for wild birds and the environment. Together with other bird and habitat conservation organisations worldwide it is part of a global partnership, called BirdLife International.

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Registered charity no. 207076

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