Light Pollution Hurts Plants and Animals

By Chris Clark, Brad Hopkins, and Betsy York

[from the Commercial Record, March 31, 2022]

Light pollution kills millions of birds every year because artificial lights disrupt their migration “calendar.”  The light causes the birds to start out too early or too late, thereby missing the best conditions for nesting. Birds that navigate by moonlight and starlight are distracted by bright lights in urban areas. They wander off course and many die, colliding into buildings that didn’t need to be lit up in the first place. Other confused birds fly around the city until they drop to the ground, dead. You don’t have to be a bird lover to understand that our planet needs these frequent flyers to distribute seeds and control pests.

(courtesy of National Audubon Society and International Dark-Sky Association)

Trees exposed to artificial light at night bud earlier, lose their leaves later, and have shorter lifespans. Plants depend on the natural cycle of day and night. Too much exposure to artificial light at night keeps the trees from adjusting to the change of seasons. Notice how the leaves on the  left side of the tree in the photo —near the streetlight— have not fallen. This disruption, in turn, has implications for wildlife that depend on trees for habitat.

A streetlight caused leaves on part of this tree to hold on too long (M. Tuhárska)

As soon as certain types of turtles hatch on the beach they must find the ocean. It should be the brightest thing they see, reflecting the moon and stars in the night sky. Unfortunately, artificial lights confuse the hatchlings and many don’t make it to the ocean. Hundreds of thousands die annually — a fact that, once again, has an impact on the ecosystem. Turtles help control the jellyfish population and keep seagrass beds healthy. Their leavings are an important source of food for coastal vegetation, and hatchlings are a source of food for fish.

This is a very limited peek at the long list of wildlife known to be affected by light pollution. A few others include coral, butterflies, fish, and geckos.

Dark Sky Action Item 3: Does your porch light attract bugs? The bluish-white color of a typical light bulb is easy for them to see, plus insects are attracted to brightness and heat. Try a lower-wattage LED “bug light” with a 2000K color rating. It’s not as bright, emits less heat, and is harder for bugs to see. A shielded light fixture will also help.

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