Bats are a frequent consideration when it comes to development projects and ecology. One of the main recommendations when bats are a consideration is the design and inclusion of a sensitive lighting scheme into a project. But what does this mean, how can it be achieved and why is it so important?
Let’s begin with a quick reminder regarding bats and the law. All bat species and their roosts are currently protected by law; legislation makes it an offence to destroy, damage or block access to a bat roost, or to deliberately or recklessly disturb, injure or kill any bat. The roost is protected whether bats are present or not.
Bats are generally active at night and utilise a wide range of habitats for foraging and commuting between roost sites, hibernation sites and foraging habitats. Linear features such as hedgerows, woodland edges and even fences can be important for navigation between roosting and foraging habitats.
Bats have seen significant declines over the last century and are still vulnerable to threats such as habitat fragmentation and habitat loss.
Lighting and bats – what’s the problem?
Lighting can result in significant disturbance to bats. It can delay the emergence of some species from their roosts, resulting in them missing out on peak foraging times for insects; it can lead them to abandon a roost site; or can even act to ‘entomb’ bats within a roost.
Lighting of habitats and features that bats use for commuting, dispersal and foraging can restrict their movement, make them vulnerable to predation and lead to them being isolated from important habitats and resources.
What’s the solution?
There are a number of ways that lighting can be designed within a development project that ensures that bats are not negatively affected. The simplest solution is to avoid any increase in light levels in relation to key habitats or features.
Where it is necessary to include lighting, a number of measures can be introduced to mitigate its effects on bats. The Bat Conservation Trust (BCT) has developed guidance to assist with this. Measures recommended include: dark buffer zones, sensitive site configuration, minimising light spill, targeted lighting, screening, glazing treatments, dimming and part-night lighting.
Our licensed bat ecologists are highly experienced when it comes to working with clients on projects where bats are a consideration. If you have any questions when it comes to bats and lighting, please do not hesitate to contact us.
 Bat Conservation Trust and Institute for Lighting Professionals (2018) Guidance note 8. Bats and Artificial Lighting. https://www.theilp.org.uk/documents/guidance-note-8-bats-and-artificial-lighting/