Maybe to the kitchen or to your closet for a jacket. Not everyone enjoys this luxury. Every year, migratory birds travel several thousand kilometres to adapt their habitat to their needs. And every year many of these birds have to die – because of climate change, because of illegal animal killing, because of light pollution, because of us. Although these factors are not stoppable by one single person, we can try to make a contribution to easing their path even with the smallest things, like switching off the lights.
How exactly are migratory birds endangered by us and what can we do about it?
In addition to direct human threats such as the killing of rare migratory birds, it is above all unconscious man-made changes in the environment that have an extreme influence on bird migration at night. It is estimated that in Europe and North America 99% of all people currently live under a so-called "lit sky", worldwide it is more than 80%. Light pollution is increasing in all places on the planet. The amount of artificial light on the Earth's surface increases by at least 2 per cent every year and could be even greater.
For wild animals, especially migratory birds, the increasing light pollution is a honourable threat. It causes the death of millions of birds every year.
Migratory birds face dangers such as exhaustion, predation and fatal collisions with buildings, simply because of depleted energy reserves. The birds are attracted by artificial light at night and become disoriented mainly when there is low cloud, fog, rain or when flying at low altitude. Thus, they may circle in illuminated areas.
Light pollution can also alter the birds' migration patterns, as well as their foraging behaviour and vocal communication. These problems are mainly caused by the fact that man-made light pollution changes the natural patterns of light and dark in ecosystems.
At the Convention on the Conservation of Migratory Species of Wild Animals 2020, guidelines on the light pollution affecting seabirds and migratory shorebirds were endorsed. They include the special consideration of the likely wild species that could be impacted, the main sources of light pollution and facts about proximity to important habitats and migratory pathways. The parties of the convention are currently developing new guidelines focusing on bats and migratory landbirds.
However, many measures are already being taken to minimise light pollution. In numerous cities, governments and companies, initiatives such as “Lights Out” programmes are working to protect migratory birds. Guidelines for bird-friendly buildings, such as requests to turn off unnecessary lighting during migratory periods, attempt to eliminate light pollution as a hazard.
Many states and cities are trying to reduce light pollution by shifting to LED street lights which use less energy and have less of an effect on plants than traditional street lights with longer wavelengths and requiring shields to control where the light goes.
These native plants provide birds with the energy requirements needed for a long migration. They produce fleshy fruits which are very important during the late summer and fall. Others offer a variety of resources including flowers that provide nectar, fleshy fruits, acorns and nuts, seeds, and insects.
Migratory birds are a source of recreation for millions of bird watchers and enthusiasts who provide food and design backyard habitats to attract a variety of species throughout the year. But not only that: They provide ecosystem benefits that include pest control, pollination of plants and serve as food sources for other wildlife.
To preserve these important influences on our lives and the planet, and to make life easier for migratory birds, we need to take action now. It is time to take tougher action against climate change and turn off the lights when they are not needed.
Dim the light not only for your electricity bill, but also for birds at night.