Happy World Migratory Bird Day! I hope you are able to get out and enjoy watching the birds today. The 2022 theme for World Migratory Bird Day is light pollution.
Many bird species migrate at night, so light pollution from populated areas disorients their navigation, disturbs their internal clocks, and cause numerous collisions every year. In the United States alone, 100 millions birds die annually from collisions with buildings. Building collisions can happen during the day too, but the lights at night add an extra threat by attracting birds to the area, in the same way that your porch light attracts moths.
A study published in the journal Nature in 2020 found that light pollution is starting to impact breeding habits of some birds species as well. The researchers analyzed how noise and light pollution impacted breeding success of 58,506 nests from 142 North American species. They found that light pollution leads species of open habitats such as grasslands to breed up to a month earlier and 18 days earlier in forested environments. In forested habitats noise pollution was more disruptive than for open habitat birds, causing some species to delay breeding. These changes in breeding habits can cause temporal mismatch which could lead to higher mortality rates due to weather events and difficulties finding food sources.
According to the World Migratory Bird Day website, artificial light is increasing by 2% each year globally. While that may not seem that much, this increase is having adverse effects not only on birds, but other species including humans. There are 4 components to light pollution: glare (excessive uncomfortable brightness), clutter (bright confusing groupings), skyglow (brightening of the night sky in inhabited areas), and light trespassing (light in unwanted or not intended areas). According to the International Dark-Sky Association, 80% of the global population lives under skyglow and up to 99% of the public in Europe and the United States can’t experience natural night! Industrial civilization is the root cause of light pollution. Light pollution also affects melatonin production, discombobulates circadian rhythms, disrupts ecosystems, and increases energy consumption.
Lights Outs is a program created by the National Audubon Society to combat light pollution. The program encourages building managers and owners to turn off excess lighting during migration season to make it easier for birds to travel. Lights Out has found success in many cities throughout the United States and is becoming more popular over time. Individuals can participate in Lights Out events too.
So what can be done to help birds and reduce light pollution? Here are some simple steps you can take:
- Turn off unnecessary lights. Only use lighting if needed.
- Set lights on a timer or motion detector
- Keep blinds closed to keep light inside.
- Participate in citizen science projects to measure light pollution such as Globe at Night , Cities at Night, or track on your smartphone using apps such as The Dark Sky Meter app. Check out the “Measuring Light Pollution” page at The Dark-Sky Association website for more information to get involved.
- Support programs such as Lights Out
- Spread the word about light pollution to you friends and family. Knowledge is power!
- Bishop, M. (2018). Dangerous Skies: Estimated Annual Mortality from Collision Threats to Birds [Online Image]. BirdCast. https://birdcast.info/science-to-action/lights-out/
- International Dark-Sky Association. (n.d.). Light Pollution. International Dark-Sky Association. https://www.darksky.org/light-pollution/
- NSF Public Affairs. (2020). Noise and light pollution affect breeding habits in birds. National Science Foundation. https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=301714&org=NSF
- UNEP/CMS Secretariat and UNEP/AEWA Secretariat. (2021). World Migratory Bird Day 2022 Theme to Focus on Light Pollution. World Migratory Bird Day. https://www.worldmigratorybirdday.org/news/2021/world-migratory-bird-day-2022-theme-focus-light-pollution
- World Migratory Bird Day in the Americas. (2022). Dim the lights at night for birds. Migratory Bird Day.org. https://www.migratorybirdday.org/conservation-theme/