Bat boxes are similar to bird boxes but the entrance is a slit rather than a hole and it is underneath rather than at the front. Some form of grip is provided, usually by using a grooved back plate or rough-sawn wood.

Siting a box requires a little thought. Bats like to fly to a roost along a sheltered, linear path such as a hedgerow or line of trees so aim for this kind of site as a first choice. In groups of trees choose an outer one with easy access. Fix the box as high as possible but at least 2m high and a minimum of 5m for noctule bats. A wall or tree is ideal. Pole mounts also prove successful. If attached to a wall allow enough room for access if required. If attached to a tree the tree must be able to grow without damaging the box. Therefore, fix with headless or domed nails or straps (and be aware of where it may fall!). Nails should be aluminium of the tree is likely to be pruned or felled as they do not damage saws and chipping machinery. Tree ties are ideal. Bats drop out of boxes before stretching their wings so make sure there is a clearance of 12cm (5") below the box. 12cm (5") is also required around the entrance.

For summer roosting, bats like a warm south-west to south-east facing box. Avoid obstructions in the flight path such as tree branches. For winter roosting, bats prefer a cool north position, making multiple boxes a real bonus.

As boxes can become too hot or cold you could fix four boxes facing in all directions around a single tree so that the bats do not have to travel far to find alternative accommodation. You can join boxes together to form breeding boxes for maternal colonies.

Bat boxes have very high occupancy rates when sited well and left alone. If a bat box has not been used within 2 years, however, and there are no obvious reasons such as a blocked entrance, it would be wise to try a different location.

Bats prefer their homes to smell natural rather than disinfected so there is no need to clean them. If you do decide to, make sure it is at a time when the box is not occupied, for example when they have moved on to different winter or summer quarters, and simply brush out any droppings (which incidentally make an excellent garden fertiliser).