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World Biodiversity Forum: The Light of the Earth

Light pollution – from street lamps to floodlit monuments – is disrupting insects, birds and mammals alike, causing them to become disorientated and upending their natural feeding, breeding and migratory patterns.

Modern highways, for example, can become insurmountable fences running through the landscape, attendees at the World Biodiversity Forum were told on Monday.

In a series of presentations, researchers showed how different light shapes, strengths and colours can impact a range of creatures from butterflies to badgers.

It could be the 9/11 Memorial in New York, the intensive tomato farms of The Netherlands, or oil rigs that appear like lit-up islands in the North Sea.

“You have this effect on the motivation (of creatures) for when to move and how to move,” Gregor Kalinkat of the Leibnitz-Institute to Freshwater Ecology and Inland Fisheries said.

Bats and insects can become prey as a result of either clustering around light or being disorientated by it. In one case, research showed birds laying eggs three days earlier than their natural cycle as a result of light disruption.

The presentations at the Forum, which is being held in the Swiss town of Davos, came just a few days after the Convention on the Conservation of Migratory Species of Wild Animals for the first time included guidelines for combatting the impact of light pollution.

New research presented at the Forum showed that the shape of light rather than its colour had the most impact on insects.

The WSL Swiss Federal Research Institute set up lights of two shapes (straight down and diffuse) and three colours (amber, warm white and neutral white), and trapped nearly 15,000 insects over 102 nights.

Diffuse lights were the deadliest. As for colour, neutral white attracted the most victims.

Separate research has suggested that red lights have the least impact on wildlife other than birds, which are least bothered by green.

It is unlikely the world will turn off its lights, but such findings may help authorities choose lighting that is least disruptive.