Garden lighting: effects on wildlife

Used sparingly, lights in the garden can enhance its night-time charms, but what about the effects on wildlife?

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Frogs seem to be attracted to light. Credit: RHS.

Quick facts

The breeding success of glow worms is adversely affected by artificial lighting
Bats show disrupted feeding patterns in lit areas
Robins extend their activity period in artificial light, feeding longer and singing in the middle of the night
Moths and nocturnal-flying migrating birds can be disorientated by light sources and urban areas

How to effectively use garden lighting

Gardeners often use garden lighting to brighten up their garden at any time of year - from summer parties to winter viewings.

  • Lighting in gardens can illuminate particular features and create a welcoming place to sit in the evenings but can negatively impact on wildlife
  • Security lighting is another major use of light in gardens, positioned to catch the movement of visitors or intruders, often around entrances and the sides of buildings
  • Low-voltage, easy-to-install kits can be plugged into a pre-existing mains socket, and usually have smaller light fittings than mains electricity lighting, which is only really necessary for illuminating large gardens or big trees
  • A registered electrician must be used for all mains garden installations

Lighting and wildlife

The potential effects of lighting on wildlife and the environment is often overlooked. Evidence suggests all forms of artificial lighting (including LEDs and halogen) can impact on wildlife. Light pollution from inappropriately positioned security lighting is often the worst culprit.

Impact on wildlife

  • Artificial light in gardens disrupt natural behaviour for some wildlife so it's important to retain some dark areas
  • Nocturnal insects, including many moths navigate in part by natural light sources, such as the moon, and can become disorientated by artificial light, wasting energy and reducing their efficiency as nocturnal pollinators
  • Many bat species avoid lit areas altogether and although some bats are more tolerant and take advantage of the accumulation of insects at artificial lights to hunt, it can then open these species up to the risk of predation
  • Security lights may temporarily blind some animals and may even attract them, as appears to be the case with frogs
  • Garden birds are disturbed from sleep by sudden lighting and can begin singing before dawn. Robins especially seem sensitive to light and will extend their feeding period into the night where artifical light is present. Owls may find hunting more difficult in lit, urban areas and birds that prefer to start migration flights at night can become disorientated
  • Disruption of animals’ breeding cycle is more serious. Light pollution is thought partly to blame for the decline of glow worms; these emit low, greenish light to attract mates
  • Dim lights, such as white solar powered lights, are less likely to affect wildlife. But avoid coloured solar lights as these seem to confuse and attract glow worms

Minimising impact

  • Ask yourself whether you really need lighting
  • Lessen the effects of lighting by positioning lights as low as possible and aiming lights responsibly
  • Turn garden lights off when not in use or use motion sensors or timers for essential or security lighting
  • Hoods can also direct the light downwards to reduce light pollution of the night sky
  • Choose low-intensity lighting and warmer hues (warm white, yellow or amber): solar lighting is cheap, safe and emits a dull glow suitable for garden use
  • Encourage local councils to adopt switch-off schemes for street lighting: even part-night lighting instead of full-night lighting has been found to reduce negative impact on the behaviour of moths

Measures to reduce negative impacts of lighting on wildlife are also likely to be beneficial in reducing adverse impacts on people - see Chapter 4 page 4 'Light pollution and health' from the UK Government's Annual Report of the Chief Medical Health Officer 2017: Health Impacts of All Pollution - what do we know?

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