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Light pollution has complex effects on animal vision - University of Exeter

A photo of a foxglove calibrated to different visual systems and artificial light types. From left: human vision in sunlight, hawkmoth moonlight, hawkmoth white LED, hawkmoth PC amber LED. Hawkmoth images are shown in "false colour" with their green, blue and ultraviolet sensitivities shown in the place of human red, green and blue respectively. Credit Jolyon Troscianko
A photo of a foxglove calibrated to different visual systems and artificial light types. From left: human vision in sunlight, hawkmoth moonlight, hawkmoth white LED, hawkmoth PC amber LED. Hawkmoth images are shown in "false colour" with their green, blue and ultraviolet sensitivities shown in the place of human red, green and blue respectively. Credit Jolyon Troscianko

Changes in the colour and intensity of light pollution over the past few decades result in complex and unpredictable effects on animal vision, new research shows.

Insect attraction to light is a well-known phenomenon, but artificial lighting can also have more subtle consequences for species that rely on night-time vision for their behaviour.

To explore these effects, University of Exeter researchers examined the impact of more than 20 kinds of lighting on the vision of moths, and birds that eat them.

The study found that elephant hawkmoth vision was enhanced by some types of lighting and disrupted by others, while the vision of birds that hunt moths was improved by almost any lighting.

Night-time lighting is increasing rapidly worldwide, and has changed dramatically in the last 20 years, as amber (low-pressure sodium) streetlights are replaced with a diverse range of modern lights such as LEDs.

"Modern broad-spectrum lighting allows humans to see colour more easily at night," said Dr Jolyon Troscianko, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.

"However, it is difficult to know how these modern light sources affect the vision of other animals. Hawkmoth eyes are sensitive to blue, green and ultraviolet, and they use this colour vision to help find flowers just like bees, but at incredibly low light levels – even under starlight. Moths are also vitally important pollinators – accounting for a similar proportion of pollination as bees – so we urgently need to investigate how lighting affects them.”

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