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Houses for bats

Mike Waite

Bat houses are not such a new idea. Over a century ago in the United States, bat droppings – ‘guano’ – was collected as a source of nitrate to make fertiliser and gunpowder, and this became easier when it was realised that bats could be attracted into special wooden tower roosts or ‘cotes’. Similar structures can still be seen around American houses today – put there just for the joy of seeing bats, not to mention the effect of their residents on reducing the numbers of annoying mosquitos!

Most British bats have evolved as creatures of forests and naturally roost in trees. No wonder they quickly adapted to living in the roofs of timber-built dwellings, full of nooks and crannies to hide away in. The problem here is that bats are in effect our guests and must live with the inevitable changes that go on – roof extensions and restoration, repair work and even demolition. Too many bat roosts are happily accepted by one owner, only to be moved on by their successors. Although wildlife law is supposed to ensure the minimum disturbance to bats in this process, they are nevertheless reliant on the continuing goodwill of their human hosts.

What better then, than to build a house (or indeed part of a human dwelling), totally dedicated to the needs of the bats, where continuity of use is guaranteed and all the features that we’ve learnt from experience attract them are designed-in from the outset? This is the overall concept of a ‘bat house’ and they are being built – bat lovers all over the country are experimenting with various designs, sometimes as expert consultants on projects where a particular development is conditional on building a bat house or roof, or just because they want to see if their design works!

There are recent examples of just this happening in Gloucestershire, South Wales, Scotland and in Cheshire. The latest ideas acknowledge the importance of high summer temperatures to breeding bats, and ingeniously attempt to incorporate heating devices, even using sustainable sources of energy. In London, too, there are already a few examples of special winter bat houses, or ‘hibernacula’. At its Crossness Nature Reserve near Erith in southeast London, Thames Water has built an artificial cave which will provide a secure home for hibernating bats. In several other places, small disused buildings have been converted for autumn and winter use by bats, mainly on nature reserves. These include a site at the Hainault Lodge Local Nature Reserve in Redbridge; a former army defensive pill-box in the Beam Valley country park in Dagenham; and two old railway tunnels – one at Highgate and the other at Feltham in Middlesex. Another tunnel soon to be converted is that at Sydenham Wood in Dulwich.

However, there is still no up-scaled (from the humble bat-box) bespoke structure that can accommodate bats year-round. Jeremy Deller’s Bat House at the London Wetland Centre will therefore be a complete pioneer in this respect and, we hope, the first of many more to come.

Mike Waite is Senior Policy Adviser (Biodiversity), Greater London Authority London Bat Group, London Bats Species Action Plan Co-ordinator

'Stark' design Bathouse Texas. Bathouses were constructed in Texas near to crops to attract bats to the area so they would eat insects. They were also built near to lakes in an attempt to keep mosquito numbers down, as some specoies of bats can eat up to 2000 insects in one night. These houses are still used and are now listed monuments in the state.



Crossness Bat Cave