The effects of night lighting on wildlife have been known for hundreds, even thousands, of years. Hunters and fishers have used torches, lamps, and other light sources to attract their quarry to them, so powerful is the effect of light on some species.
Sea turtles are the most well-known species of reptiles that are negatively affected by artificial light. Female turtles nest on subtropical and tropical beaches around the world. About two months later, the hatchlings burst from the nest en masse and start scrambling to the brightest horizon. On a natural beach, this is toward the moon and starlight glimmering off the water, and away from the shadowy dune. Artificial lights cause a problem for hatchlings because they lead the small turtles away from the safety of the water, where they succumb to dehydration, predators, or even being run over by cars. They also affect nesting females, who may spend valuable energy moving toward lights and away from the water instead of returning to the sea after nesting. Tragically, nesting females may also be attracted to roads where they are hit by cars. The loss of a female who has, against the odds, made it to reproductive age is a significant loss to these threatened and endangered populations.
Turtle Friendly and Turtle Safe Lighting is a procedure of using a certain amber/red color (580nm) for the light bulbs, which decreases light polution. Keeping the light mounted as low to the ground as possible and/or fully shielding the light so bulbs and/or glowing lenses are not visible) cuts down on the amount of glare and light visible to the animals, so that there is less opportunity for them to get trapped, repelled, or have their day/night patterns altered. The amber/red color makes the light that is visible seem dimmer to nocturnal animals that primarily use rod vision. The rod system's peak sensitivity is at 496 nm, so a low pressure sodium light, with its emitted light at 589 nm, should seem 1/10th as bright to an animal using purely rod vision vs. an animal that uses rods and cones to see.
Changing to LOW, SHIELDED, and LONG wavelength lights also results in energy savings. For instance, lights that are lower and shielded often result in more lumens (light) being focused onto the ground, rather than wasted illuminating the sky above the light. Additionally, some long wavelength light sources such as low pressure sodium lights and amber LEDs use a fraction of the energy of their mercury halide, incandescent and even fluorescent counterparts
Wildlife Lighting, LLC.
Phone: (215) 275-1813
Photo taken by Karen Shudes, Sea Turtle Lighting Specialist -with the Sea Turtle Conservancy