Action

Action Synopsis: Bat Conservation About Actions

Use red lighting rather than other lighting colours

How is the evidence assessed?
  • Effectiveness
    50%
  • Certainty
    50%
  • Harms
    0%

Source countries

Key messages

  • Three studies evaluated the effects of red lighting on bat populations. One study was in the UK, and two studies were in the Netherlands.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (2 STUDIES)

  • Abundance (2 studies): One replicated, controlled, site comparison study in the Netherlands found that red lighting resulted in higher activity (relative abundance) for one of three bat species groups than white or green lighting. One site comparison study in the Netherlands found that culverts illuminated with red light had similar activity of commuting Daubenton’s bats as culverts illuminated with white or green light.

BEHAVIOUR (1 STUDY)        

  • Behaviour (1 study): One replicated, controlled study in the UK found that more soprano pipistrelles emerged from a roost when lit with red light than when lit with white light, but no difference was found between red and blue lights.

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, controlled study in 2000 at two bat roosts within buildings in Aberdeenshire, UK (Downs et al. 2003) found that when roosts were illuminated with red light more soprano pipistrelles Pipistrellus pygmaeus emerged than when roosts were illuminated with white light, but no difference was found between red and blue lights. At both roosts, more bats emerged when the roost entrance was illuminated with red light (13 and 72 bats) than when it was illuminated with white light (2 and 24 bats). No difference was found between red and blue light (6 and 62 bats emerging) at either roost. A hand-held halogen light with coloured filters was placed within 3–5 m of each of the two roosts. Over 20 nights in July–August 2000, nights with roosts unlit and nights with lighting were alternated. On nights with lighting, white, blue and red lights were rotated in a random order and changed every 30 seconds. On each of 20 nights, the number of bats emerging per 30 second interval was counted at dusk.

    Study and other actions tested
  2. A replicated, controlled, site comparison study in 2012–2016 at eight forest sites in the Netherlands (Spoelstra et al. 2017) found that red lighting had higher activity for one of three bat species groups than white or green lighting, and similar activity was recorded for all three species groups in red lighting and darkness. For Myotis and Plecotus spp. more bat passes were recorded in red light (66) and darkness (67) than in white (31) and green light (22). For Pipistrellus spp. fewer bat passes were recorded in red light (5,940) and darkness (3,655) than in white (17,157) and green light (9,695). None of the light treatments had a significant effect on the number of bat passes recorded for Nyctalus or Eptesicus spp. (red light: 495; white light: 719; green light: 950; dark: 521). At each of eight sites, one 100 m transect was set up for each of four treatments (red light, white light, green light or left dark). Five 4 m high light posts were installed along each transect. Lights (8 lux) were turned on from sunset to sunrise. Bat detectors recorded bat activity for 5–15 nights/transect in June–July and August–September in each year between 2012 and 2016.

    Study and other actions tested
  3. A site comparison study in 2015 of two road culverts near Elburg, Netherlands (Spoelstra et al. 2018) found that culverts illuminated with red light had similar activity of commuting Daubenton’s bats Myotis daubentonii as culverts illuminated with green or white light. The average number of Daubenton’s bat passes did not differ significantly between culverts illuminated with red (43 bat passes/night), green (37 bat passes/night) or white light (39 bat passes/night). Activity was similar when culverts were left unlit (34 bat passes/night). Two light-emitting diode (LED) lamps of three colours (red, green, white) were installed on the ceiling of each of two identical, parallel road culverts (31 m long, 1.6 m diameter) carrying a stream. Different light treatments (unlit; red, green, or white light at 5 lux intensity) were applied simultaneously in each of the two culverts with treatments changed each night over a total of 47 nights in July–August 2015. Two bat detectors fitted alongside the lamps in each of the two culverts recorded bat activity.

    Study and other actions tested
Please cite as:

Berthinussen, A., Richardson O.C. and Altringham J.D. (2019) Bat Conservation. Pages 67-140 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.

 

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Bat Conservation

This Action forms part of the Action Synopsis:

Bat Conservation

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence in synopses. Subjects covered so far include amphibians, birds, terrestrial mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read latest volume: Volume 17

Go to the CE Journal

Subscribe to our newsletter

Please add your details if you are interested in receiving updates from the Conservation Evidence team about new papers, synopses and opportunities.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust