World Migratory Bird Day illuminates the dark side of light pollution

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Light pollution is increasing, with artificially lit outdoor areas rising by 2.2 per cent per year from 2012 to 2016, according to one study cited by the Secretariat of the Convention on Migratory Species of Wild Animals (CMS), a UN environmental treaty.

Currently, more than 80 per cent of the world's population is estimated to live under a “lit sky”, and the figure is closer to 99 per cent in Europe and North America.

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Artificial light alters natural patterns of light and dark within ecosystems, and contributes to the deaths of millions of birds each year.

Light pollution can cause birds to change their migration patterns, foraging behaviours and vocal communication, resulting in disorientation and collisions.  

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Migrating birds are attracted to artificial light at night – particularly when there are low cloud conditions, fog, rain, or when flying at lower altitudes -  luring them to dangers in cities.

Birds become disorientated and, as a result, may end up circling in illuminated areas. With their energy reserves depleted, they risk exhaustion, or worse.

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Two years ago, countries that are party to the CMS endorsed guidelines on light pollution covering marine turtles, seabirds, and migratory shorebirds.

The recommendations call for Environmental Impact Assessments to be conducted for projects that could result in light pollution.  

Projects should consider the main sources of light pollution at a certain site, the likely wild species to be affected, and facts about proximity to important habitats and migratory pathways.

New guidelines focused on migratory landbirds and bats are currently being developed and will be presented for adoption at a CMS conference next year.

[...] More and more cities worldwide are taking measures to dim building lights during migration phases in spring and autumn, according to the UN Environment Programme (UNEP).

World Migratory Bird Day is celebrated twice a year, on the second Saturday in May and October, in recognition of the cyclical nature of bird migration and the different peak migration periods in the northern and southern hemispheres.

(PM UN, gekürzt)

The full article can be found at news.un.org