Bats and Boxes

Bats are amazing animals that are important to ecosystems in the UK and worldwide. We have 18 species of bat in the UK, all of which are protected under European law. Bat populations in the UK have declined dramatically over the past century due to persecution and habitat loss. However, some UK bat species have recently shown some signs of increasing so there is hope.

Bats don’t make nests but rely on finding suitable places to rest – roost. The 18 species not only have varying preferences from each other, but each species has different requirements within themselves, such as summer compared with winter and a breeding female compared with an individual male. A good place to start to find out more about the different species is the Bat Conservation Trust http://www.bats.org.uk/pages/uk_bats.html or with this link for Young People’s Trust for the Environment http://ypte.org.uk/factsheets/bats-british

Boxes are artificial roosts designed to provide bats with alternative resting places or to encourage bats into areas where there are few existing suitable roost sites. Providing bat boxes can increase opportunities for roosting bats but it can take a while for bat boxes to be used regularly, particularly where several suitable alternative roost sites exist.

Bat boxes can have an important additional function in encouraging interest and educating members of the public about bat conservation. The correct design and placement of boxes will help increase the likelihood of their uptake by bats.

Bat roost preferences

Some knowledge of what bat species are in your local area and their preferences will help you choose the best possible box type. Some species such as horseshoe bats and grey long-eared bats do not use bat boxes. Microclimate within a new roost is a very important factor in terms of increasing the chance of successful uptake by bats. In general, they prefer warm spaces in the summer for rearing young and cooler spaces in the winter for hibernation.

Orientation and location

Structures for summer roosting should be positioned where they are sheltered from the wind but unshaded for most of the day. Summer maternity roosts (in the northern hemisphere) should be on a south-easterly to south-westerly aspect. It is always best to provide a number of different options for bats so that they can choose the most appropriate temperature based on their needs. This can be achieved by grouping a few bat boxes each with a different aspect; two or three boxes is preferable to one, although a single box still has a chance of being used depending on the bat species that use the local area. Three boxes can be arranged around the trunk of larger trees – see below for details about putting up bat boxes. Bat boxes are more likely to succeed in areas where there is a good mixture of foraging habitat, including trees, and a source of water (most maternity roosts are located within a short distance of permanent fresh water such as a stream, pond, river or lake). Bat boxes in areas with few other roosting opportunities are also likely to be more successful. Bat boxes should also be located close to unlit linear features, such as lines of trees or hedgerows. Bat species use these features for navigation between their roosting sites and feeding grounds and to avoid flying in open and exposed areas. Ensure the bats approach to the box is not impeded, for example by branches – clear away underneath the box so the bats can land easily before crawling up into the box.

Other considerations

Bats are nocturnal and adapted to low light conditions. Artificial light sources should not be directed onto bat boxes or flight paths as most bat species find artificial lighting very disturbing.

Types of bat boxes

Hollow – small, medium and large. Crevice – with one, two, three or four crevices.

What type of bat might use what type of box? 

See the table below for an extract taken from the Bat Mitigation Guidelines on what type of roost specific species prefer, and with links to the Bat Conservation Trust for more information on our UK Bat Species.

Putting up bat boxes

Most bat species will use higher positioned boxes (around 4m up); assess the risk of working at height when undertaking the installation, then place the box as high as it is safe to do so. This will also help protect bats from vandalism and falling prey to cats. If working in the public realm, try to locate boxes so they are not above public walkways. Ensure the boxes are appropriately fitted, to avoid the risk of them falling off. The boxes should be checked at least annually and after high winds to ensure they are still securely in place.

On buildings

Place the boxes high up by the eaves on a building, which can also help shelter the box from the weather. As detailed above, the aspect of the box should capture sun for part of the day if the intention is to attract maternity colonies.

On trees

Consideration should be given to tree growth and boxes may need rehanging over time, regularly check boxes to assess this. Use headless or domed nails not fully hammered home to allow the tree growth, again regular checks will ensure that this allowance can be made while still being securely fitted. Iron nails can be used on trees with no commercial value. Copper nails can be used on conifers, but aluminium alloy nails are less likely to damage saws and chipping machinery. Monitoring bat boxes

Putting up bat boxes is a great conservation action but what is even more useful is to know whether they are being used, when and by which species. How long before bats will use the box? Sometimes it can take several years for bats to find a new box. Be patient! Slow (or no) uptake may be due to the availability of other roosts locally. Sometimes, however, bats move in within months or even weeks! To check if the box is being used, look out for droppings below the box and listen for ‘chattering’ during the day, especially during the summer months. You can also watch the box for an hour either side of sunset to observe any bats leaving to feed, or around dawn to see any bats returning to their roost. Bats may be observed by looking up into the box from below, however no light should be used as this may disturb any bats that are present.

Licensing and the law

You can find out more about licensing and bats on the Bat Conservation Trust website at: www.bats.org.uk/pages/licensing.html

All bats and their roosts are protected by law and it is an offence to deliberately disturb, handle or kill bats. The relevant legislation in England & Wales is the Wildlife and Countryside Act 1981 and Conservation of Habitats & Species Regulations 2010 (as amended). In Scotland it is the Conservation (Natural Habitats, etc.) Regulations 1994 and in Northern Ireland the Conservation (Natural Habitats, etc.) Regulations (Northern Ireland) 1995.

A bed without breakfast?

Bats often use features such as hedgerows, tree lines and watercourses as commuting pathways between roosts and foraging areas. This type of habitat also provides shelter, allowing insects to gather and therefore supports foraging bats. The highest densities of bats occur where insects are most plentiful. Make sure you maintain or create good foraging habitats for bats by planting a wide range of plants such as flowers that vary not only in colour and fragrance, but also in shape. See BCT’s ‘Encouraging Bats’ leaflet for more information www.bats.org.uk\publications.

Other useful websites

Bat Conservation Trust www.bats.org.uk

The Bat Conservation Trust (BCT) is working towards a world where bats and people thrive in harmony, to ensure they are around for future generations to enjoy. BCT is the only organisation solely devoted to bat conservation in the UK.

Bat Conservation International www.batcon.org

Bat Conservation International’s mission is to conserve the world’s bats and their ecosystems to ensure a healthy planet. Based in Austin, Texas, BCI is devoted to conservation, education and research initiatives involving bats and the ecosystems they serve.

Roost www.roost.bats.org.uk

Roost is a resource developed by the Bat Conservation Trust (BCT) to aid in the gathering of information on bat roost mitigation, compensation and enhancement techniques. The aim is for this site to provide accessible information to support everyone involved in bat conservation and development.

Vincent Wildlife Trust www.vwt.org.uk

The Vincent Wildlife Trust (VWT) is an independent charitable body founded by Vincent Weir in 1975 and has been supporting wildlife conservation ever since. They conserve a range of endangered mammals through management of their own reserves, undertake pioneering research and provide expert advice to others through practical demonstration.

Publications

Gunnell, K., Murphy, B. and Williams, C. (2013) Designing for biodiversity: a technical guide for new and existing buildings (2nd ed.) Gunnell, K., Grant, G. and Williams C. (2012) Landscape and urban design for bats and biodiversity Mitchell-Jones, A.J (2004) Bat mitigation guidelines Mitchell-Jones, A.J. and McLeish, A.P. (2004) Bat workers’ manual (3rd edition) Tuttle, M.D., Kiser M. and Kiser S (2004) The Bat House Builder’s Handbook

Greenwood’s Ecohabitats give 10% of Bat Box sales (not profits!) to the Bat Conservation Trust.

 What type of bat might use what type of box? 

Key

*                - Large well-insulated hibernation boxes may be more successful

N/A           - not applicable; bat boxes should not be considered as replacement roosts

Hollow     - tree hollow-type box, providing a void in which bats can cluster

Crevice     - tree crevice-type box, with 15-35mm crevices

?                - few data on which to base an assessment

Species  Common name

Summer/

maternity

Summer/

non-breeding

Hibernation Notes
Rhinolophus ferrumequinum Greater horseshoe bat N/A N/A N/A Horseshoe bats do not use bat boxes
Rhinolophus hipposideros Lesser horseshoe bat N/A N/A N/A

Myotis bechsteinii

Bechstein’s bat Hollow Hollow   Maternity roosts

Myotis brandtii

Brandt’s bat Hollow Hollow    

Myotis daubentonii

Daubenton’s bat Hollow Hollow    

Myotis mystacinus

Whiskered bat Hollow Hollow    

Myotis nattereri

Natterer’s bat Hollow ?    
Pipistrellus nathusii Nathusius’ pipistrelle Hollow Hollow    
Pipistrellus pipistrellus Common pipistrelle Crevice C/H Crevice H are rarely used as maternity roosts. 
Pipistrellus pygmaeus Soprano pipistrelle Crevice C/H Crevice

Nyctalus leisleri

Leisler’s bat Hollow Hollow Hollow?  

Nyctalus noctula

Noctule Hollow Hollow Hollow  
Eptesicus serotinus Serotine N/A N/A N/A Not found in boxes
Barbastella barbastellus Barbastelle Crevice ? Crevice?  
Plecotus auritus Brown long-eared bat Hollow Hollow   Maternity roosts
Plecotus austriacus Grey long-eared bat Hollow ?    
Extract taken from Bat Mitigation Guidelines 2004 – English Nature