Action Synopsis: Bat Conservation About Actions

Use ultraviolet filters on lights

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • One study evaluated the effects of using ultraviolet filters on lights on bat populations. The study was in the UK.



  • Abundance (1 study): One randomized, replicated, controlled study in the UK found that hedges lit with ultraviolet filtered lights had higher soprano pipistrelle, but not common pipistrelle activity (relative abundance) than hedges lit with unfiltered light.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, randomized, controlled study in 2014 at five hedges in Devon, UK (Mathews et al 2015) found that hedges lit with ultraviolet (UV) filtered lights had higher activity for one of two bat species than at hedges lit with unfiltered lights or unlit hedges. Soprano pipistrelle Pipistrellus pygmaeus activity was higher at hedges lit with UV filtered lights (average 5 bat passes/night) than at hedges lit with unfiltered lights (3 bat passes/night) or at unlit hedges (4 bat passes/night). Common pipistrelle Pipistrellus pipistrellus activity did not differ significantly between any of the light treatments (data not reported). At each of five hedges, two lights (8W LED flood lamps with additional UV bulbs) were set up 15 m apart and 5 m high. Filtered lights were covered with UV film filters to reduce UV emissions by 40%. Three treatments (UV filtered lights, unfiltered lights, unlit/control) were carried out at each pair of lights in a random order for three nights each between July and October 2014. Two additional unlit locations were also surveyed at each site. During each night, bat activity was recorded using bat detectors placed at the treatment site and at the unlit locations for 3 h from sunset.

    Study and other actions tested
Please cite as:

Berthinussen, A., Richardson O.C. and Altringham J.D. (2021) Bat Conservation: Global Evidence for the Effects of Interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.


Where has this evidence come from?

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Bat Conservation

This Action forms part of the Action Synopsis:

Bat Conservation
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