Use lights low in spectral red to reduce mortality from artificial lights

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
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How is the evidence assessed?

Effectiveness

56%
Certainty

15%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

Birds are most sensitive to red light, meaning that if bulbs used at night emit less red light then they may prove less attractive to birds, whilst remaining equally visible to humans.

Key messages

Two studies from the North Sea and the Netherlands found that fewer birds were attracted to low-red lights (including green and blue lights), compared with the number expected, or the number attracted to white or red 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

A study on an oil rig in the southern North Sea on three nights in October 2007 (van de Laar 2007) found that the number of migrating birds circling the rig was 10-50% of the number expected when the majority of external lights were replaced with ‘low red’ bulbs (150-2,500 birds observed circling vs. 750-5,000 birds expected). Low red bulbs emit lower levels of red light than standard bulbs. Attracted birds were mainly songbirds, waders and wildfowl and expected numbers were estimated based on previous observations and calculated from the number of migrating birds recorded on nearby islands, the number observed from the rig and the weather conditions.
Study and other actions tested
Referenced paper
van de Laar F.J.T. (2007) Green light to birds: Investigation into the effect of bird friendly lighting. (Nederlandse Aardolie Maatschappij (NAM) report, no. L15-FA-1, The Netherlands.
A replicated, controlled study from Friesland, the Netherlands (Poot et al. 2008), in September-November 2003, found that on clear nights, significantly fewer migrating birds were attracted to two 1,000 W lamps when they were covered with opaque white or red filters (61% of 38 birds and 54% of 13 birds reacting to each), compared with green (13% of eight) or blue (3% of 37) filters. The same pattern, but with higher overall levels of attraction were detected on overcast nights (white: 81% of 156 birds reacting; red: 54% of 24; green: 27% of 77; blue: 5% of 38).
Study and other actions tested
Referenced paper
Poot H., Ens B.J., de Vries H., Donners M.A.H., Wernand M.R. & Marquenie J.M. (2008) Green light for nocturnally migrating birds. Ecology and Society, 13, 47-47.

Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2020) Bird Conservation. Pages 137-281 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Bird Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Use lights low in spectral red to reduce mortality from artificial lights Action Link	Unknown effectiveness (limited evidence)	2	Synopsis Link
Shield lights to reduce mortality from artificial lights Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Reduce the intensity of lighthouse beams Action Link	No evidence found (no assessment)	0	Synopsis Link