Bats are nocturnal animals and are adapted to low-light conditions. This means that most bat species can find artificial lighting to be very disturbing. Artificial lights shining on bat roosts, their access points and the flight paths away from the roost must always be avoided.
If it is considered necessary to illuminate a building known to be used by roosting bats, the lights will need to be switched off at bat emergence time and during peak bat activity times. Or better still, it is usually straightforward to ensure that the light does not fall on the roost access point or the flight line away from the roost used by bats. Celebratory lighting of buildings should be limited to special occasions. Please see BCT’s specialist document on Bats and Lighting for more detailed information.
Bats and their roosts are all protected by law and bats should always be taken into account when lighting is being considered.
Guidance for Bat Workers and Lighting Engineers
BCT is working with researchers at the University of Bristol to develop a comprehensive lighting guidance document for bats. This publication should be available later in 2012.
In the menatime please continue to consult 'Bats and Lighting in the UK', an online document suitable for both bat workers and lighting engineers. It is now available as Version 3 and it is expected to undergo further updates as knowledge from ongoing bat research and changes in lighting technology develop.
The Institute for Lighting Professionals has released a new version of their Guidance for the Reduction of Obtrusive Light (see below).
- Buglife reports on the Impact of Artifical Lighting on Invertebrates
- Exmoor National Park has been designated the first International Dark Sky Reserve in Europe
What else are we doing?
As more bat workers have access to light meters, the National Bat Monitoring Programme colony counts now allow the opportunity to include information about the lux levels measured during bat emergence. Those carrying out NBMP car surveys are being asked to record the type of street lighting along their route. All this data being gathered will be important in identifying trends that will support current research.
Other useful websites