A dark sky is necessary for plants and animals to thrive
This article was originally published on Our Stories and Perspectives.
The parks in Fairfax County cover almost 10% of the land. This means that parks are near homes and businesses and in rural and urban environments. For those living adjacent to the county’s ecologically fragile parks, it is important to adopt dark sky friendly lighting and light responsibly.
Light trespass and light pollution affect wildlife and plant life in many ways — from confusing migrating bird navigation at night to having an impact in nocturnal creatures’ ability to hunt and feed at night, be they prey or predator.
Artificial light at night (ALAN) can even prevent the fireflies from finding mates in the summer. Migrating birds are especially harmed by light pollution. And high-rise buildings are particularly deadly for them; they either fly into the glass windows, killing them on impact, or the light from the building attracts them and they fly around them in circles, dying from exhaustion.
Animals are adapted to the moon and stars being the only lights visible at night, so when artificial lights become the most prevalent source of light, it harms and confuses them. Baby seas turtles are adapted to find the safety of the sea by moving toward the moon and stars and their reflection off the water. Unfortunately, the artificial light of beach towns can attract baby turtles away from the sea and lead them into danger.
The life cycles of trees and plants are also affected by artificial light at night, either by extending the fall season for them — so that they lose their leaves much later than neighboring trees — or bringing on spring too early. Similarly, outdoor lights left on at night affect pollination by moths. Some varieties of strawberry plant are dependent on the dark of night to produce its fruit. Studies have shown that streetlights near rural farms actually decrease the harvest, as they encourage the plants to leaf out instead of flower and fruit.
This tree lost most of its leaves. The only ones that remain are the ones illuminated by the parking lot lights. These leaves are getting a different signal than the rest of the tree.
Artificial light has confused this shrub. The two buds closest to the light are about to burst, but this photo was taken in October. This plant typically blooms in April and May.
Light pollution is harmful, but it is reversible. Lighting has grown as populations have grown, feeding on the myth that more light is safer.
However, well-designed lighting is safer. Light should be directed down where people need it, and light should be soft in color to protect our vision. Good lighting design benefits people and wildlife.
April 22 is Earth Day and the beginning of International Dark Sky Awareness Week.
Take a minute to reflect on the lighting at your house. Does the light point only where you need it when you need it and just the right amount? If not, consider an upgrade. Visit our new Dark Skies topic page to learn more about light pollution and how we can light responsibly to protect the night.
You can also join us in our One Dark Hour event April 22, 2022. One Dark Hour: Join us and turn off your outdoor lights from 9 to 10 p.m. and look up to enjoy the stars.
Authors: E. Kragie and T. Schwab. Schwab is the Education and Outreach Manager for the Resource Management Division of the Fairfax County Park Authority.