Affects of Light Pollution on Wildlife

By Dr. Guthrum Purdin, DVM

Our ancient ancestors were day-active people: hunting, gathering, and farming under the light of the sun. When night came on, they’d draw together, lighting fires against the dark. Today, we have the technology to illuminate the night with brilliant electric lights. While modern day lighting is helpful, it can become extremely dangerous ‘light pollution’ for the night-active animals that share the world around us.

For example, sea turtle hatchlings emerge from their nests under sandy beaches at night. They travel this way so they can get to the ocean’s protection without being spotted by gulls and other predators. But for a newborn turtle, it’s a big, complicated world—how can they know which way to go in the dark? As soon as they’re out of the nest, they look for the reflected light of the moon and stars on the waves, then head out as fast as they can. Humans inadvertently cause serious trouble for the hatchlings through the brighter lights of buildings and roads. Infant turtles see the brilliant shine of electric lights then head inland, away from safety. When the sun rises, they are disoriented, dehydrated, and easy prey for predators. This is especially devasting for Green Sea Turtles in Hawaii, a species already endangered by human-caused environmental changes. Similarly, when leaving their natal nests for the very first time, fledglings of several Hawaiian birds such as Wedge-tailed Shearwaters, Hawaiian Petrels, and Newell’s Shearwaters also use the celestial lights to guide their first flights toward the sea. City lights confuse them, leading many in the wrong direction, away from safety and food and causing them to land disoriented on sports fields and roads.

Many birds migrate at night, relying on the stars to guide them. Years ago, while traveling with friends in Las Vegas, we passed a newly opened casino with a gigantic spotlight rising like a tower into the sky. We could see hundreds of birds circling inside the beam of light like a feathered tornado, confused and disoriented, flying around and around until they collapsed from exhaustion. Lights like the one we saw in Vegas can confuse and mesmerize night fliers, trapping them in the cones of brilliance on spiraling flights. Many die from exhaustion, others, blinded by the light, crash into buildings.

Fortunately, the ingenuity that allows people to build roads and cities blazing with light also helps to find solutions. One option is using red or amber lights with longer wavelengths that are less disruptive for wildlife. Another option is full cutoff fixtures that direct light downward only, so it doesn’t attract birds at night. At the 9/11 Memorial in New York, whenever concerning numbers of birds begin to circle the light, it is turned off for
20 minutes, allowing them to disperse and continue on their migration. Other simpler solutions include dimming and reducing the overall brilliance of artificial lights, drawing curtains closed at night when lights are on, or simply turning off unnecessary lights. Organizations like the Fatal Light Awareness Program (FLAP) in Toronto focus on rehabilitating injured birds, conducting scientific research, promoting wildlife-friendly regulations, and engaging in public outreach to develop more effective responses. Together we can all make a difference.

Dr. Guthrum Purdin, DVM