“World Migratory Bird Day” is conducted twice a year to raise awareness for the conservation needs of migratory birds and their habitats. This year’s World Migratory Bird Day on 14 May and 8 October is dedicated to Artificial Light at Night (ALAN). With the slogan “Dim the Light for Birds at Night”, everyone is called upon to reduce unnecessary light at night to avoid its negative impact on migratory birds.
While light acts as a positive factor to human life, it disturbs many species including birds. It changes their behavior, space use, physiology, development, and even migration patterns (see illustration below), with often unknown consequences for their survival. For example, ALAN attracts birds and causes disorientation, leading to collisions with infrastructures and thus to millions of fatalities each year.
Simplified illustration on the effects of Artificial Light at Night on bird behaviour. (a) Songbirds usually sing during the day and rest at night. With ALAN, singing is extended into the night hours and sleep is reduced. ALAN also changes bird physiology and reproduction success. (b) Migratory birds rest and feed during the day and fly at night. Strong light sources at night can attract birds and cause bird strike, especially under cloudy conditions. (c) Visually foraging waders are more active during daytime than at night. ALAN allows them to extend their foraging time. Tactile foraging waders show smaller difference between day, night, and ALAN. Graphic by Annette Krop-Benesch and Michael Melchinger.
Despite its known effects on many species, light pollution is increasing globally. However, solutions to reduce ALAN exist and many initiatives are already in place to implement them locally, also in the Wadden Sea region. A recent report, produced within the framework of the Trilateral Dark Sky Initiative, provides an overview of the known effects of ALAN on organisms and ecosystems in the Wadden Sea and gives brief recommendations to mitigate these effects, such as reducing light respires, dimming, dynamic lighting and reducing blue content. Further information can also be found in the National Light Pollution Guidelines for Wildlife, drafted by the Convention on Migratory Species Secretariat (CMS).
The World Migratory Bird Day is a campaign by the Convention on Migratory Species and African-Eurasian Migratory Waterbird Agreement (AEWA) Secretariats.