Light Pollution’s Effects on Wildlife

It was an October night, I was standing outside on the second floor of a motel looking out to the ocean of Myrtle Beach. Out there I saw true darkness, but it was still hard to see the complete darkness for the glare of a motel light. Bugs and moths were buzzing all around it. What drew my attention the most was a monarch butterfly fluttering around it too. I wondered why it was being attracted to the light, perhaps it was looking for somewhere warm as the cool night approached.

Yin and yang, good and evil, male and female, day and night, light and dark. One cannot live without the other; we need dark as much as we need light. As I stood there watching the Monarch being attracted to the light, I thought back to the film I had recently seen, ‘The City Dark’ (2011). The film is about the affects of light pollution on us and on wildlife.

In the film, they talk about sea turtle hatchlings. The eggs are laid underneath sand, and when the sea turtles hatch at nighttime, they begin crawling towards light. Naturally, the light they are going toward is the ocean, because it’s bright from reflecting the moon and stars. Evidence that nature works in brilliant ways. But now, the baby turtles become confused and crawl in the direction of land because of the bright light pollution. If they don’t make to to the ocean in a few short hours they’ll perish of starvation.

Light pollution also affects other wildlife. Migrating birds use the night sky as a travel map. However, light pollution from buildings and cities confuses them, which causes massive amounts of birds to fly into buildings. It is estimated about a billion birds every year collide into buildings. Part of this problem is the lights being left on in the buildings at night and the reflective materials used to build them, which birds think is sky. We can help by being an advocate and working with business owners and the city to get building’s lights turned off at night, getting decals applied to the building’s exterior, or by passing ordinances to reduce unneeded light pollution.

Closer to home in our backyards, light pollution is one cause for a decline in fireflies. Do you remember as a kid seeing more lighting bugs than we do now? Light pollution causes them to miscommunicate. Their flashes of light are a mating call, which gets faded out among excess light in the environment. There are ways to help fireflies, by ceasing to use lawn and mosquito spraying, leaving leaf litter, and leaving some bark from trees laying on the ground, which all supports habitat for firefly larvae.

There are other solutions to do at home to reduce light pollution. Simply turning off unneeded outdoor lights is the easiest, only using motion lights, or using lower wattage bulbs. If you need light outside, there are ‘turtle safe’ outdoor lights that purposefully angle light downward, instead of outward and scattered into the air. Close curtains at night to block light escaping from indoors, and avoid using landscape lighting, or use it minimally and very intentionally. Let’s enjoy the dark outside just as much as the light and see how we can help our wildlife too.

light example
baby sea turtles


Natural History Museum of Utah