DBG: Bat Boxes
The British bird food shop sell bat boxes and also habitats for other wildlife - bees, hedgehogs, etc.
A local company Ebony Woodwork can supply traditional bat boxes at reasonable cost, and will undertake to make boxes to your own design. See below for plans for over-winter and soft release boxes.
The Warwickshire bat group website has some excellent information and plans if you would like to make your own boxes.
Siting and maintaining bat boxes
Please be aware that cats are one of the most hazardous predators for bats, so your bat box should be sited where cats cannot threaten the emerging bats. It is best to put them on trees, and three boxes per tree is ideal, facing north, south-east and south-west. Bats like to move around and choose boxes facing in different directions at different times of the year and in varying conditions. Make sure there are no branches around the box as bats like an uncluttered flight path to and from the box.
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.
The best way to see if the boxes are being used is to look for small, dry, crumbly droppings below the box or for the bats leaving the boxes as night falls. If you find bats are using the box, only a licensed bat worker is allowed to inspect it in the future. 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.
Once or twice a year, give the slotted opening a brush to remove any build up of dust, dirt or cobwebs that could block the opening. Also prune back any plants or tree branches that may have grown across. The best time to do this work is when the bats have left for their winter hibernation, which is from about late autumn to early spring. In particular avoid the period between June to mid-August when female bats are normally giving birth and lactating.
Reservations regarding bat boxes
Bat Boxes are a good idea in a scheme where a lot are put into a place where there is feeding habitat but few roosting opportunities - such as coniferous forest, young deciduous woodland, or highly managed mature woodland such as in parks.
In older more structured woodland there are plenty of roost opportunities in the trees.
In urban areas the houses provide hundreds of roost opportunities and, critically, these are artificially heated. We now understand just how important this is for Pipistrelle species which, of course, make up the majority of roosts.
In addition, bat boxes have a very limited life. For these reasons bat boxes are not considered suitable mitigation for the loss of a bat roost by Durham Bat group. Sticking them up is not going to do much for bats, unless the boxes are hardwood and put up as part of a big scheme. Making bat boxes is harmless but, other than major schemes run by batworkers, it does little for bat conservation.
Other boxes for bats
Here you will find plans by Colin Edwards of Essex BG for over-winter and soft-release boxes - thanks to Geoff Halfhide.
The over-winter box consists of two room, feeding area to the left hand side and hibernating area to the right hand side Both rooms are lined with cork...not quite to the ceiling so as to leave a ridge for the bats to easily hang from. The wood is pine for the main body 1.8cm thick. A thin piece of plywood secures to the inside of the side with the window trapping the two layers of mesh between the ply and the pine side of the box.. The feed area has a window which is protected ﬁrst by a 1cm wire mesh and then a finer nylon mesh (pips can escape through the 1cm wire mesh so the inner lining of nylon mesh is a deﬁnite requirement. Door hinge in the middle so as to lessen the problem of the doors swelling and sticking. A hanging cork tile is provided for the bats to roost behind. The inner ﬂoor has been raised with a piece of MDF. Plans here.
Soft release box
This is made from 5 ply marine grade plywood. The roof overhangs to front and sides to provide some protection from rain. The box is fully lined with cork. A cork panel at the rear allows bats to roost behind.
When the bats are accustomed to the environment the panel covering the exit/entry slot can be hinged down to allow bats to use the box as a normal bat box.