While artificial lights at night facilitate human activities, like exercising, walking your dog and even driving, after dark, they can have harmful effects on wildlife. Finding a balance that benefits both human and wildlife safety is necessary to coexist and reduce harm. Oikonos, in partnership with Hawaiʻi Pacific University, is studying the characteristics of artificial light that result in disorientation and death of the Wedge-tailed Shearwater (Ardenna pacifica, ‘Ua‘u kani), a native Hawaiian seabird.
Light pollution along the southeast coast of Oʻahu.
Every autumn in the Hawaiian Islands (September to December), thousands of seabird chicks leave the safety of their underground burrows and embark on their first journey to the ocean. These fledglings rely on the natural lighting from the moon and stars to navigate out to sea where they will learn to find food. Artificial lighting from man-made structures can interfere with a young seabird’s ability to navigate using natural light, confusing them and causing them to fall to the ground. This phenomenon is known as fallout, and affects seabirds globally.
On Oʻahu, Wedge-tailed Shearwaters are the species most frequently grounded by artificial lights, with a known fallout hotspot along coastal Kalanianaʻole highway in the southeast corner (from Kailua to Waimanalo). Offshore islands in this region host breeding colonies that fledge tens of thousands of ‘Ua‘u kani chicks every year. While navigating to sea, many fledglings are drawn towards the main island and become disoriented by the lights along the highway. Once grounded, they are vulnerable to predation, starvation, and collisions with vehicles.
Wedge-tailed shearwaters grounded by light pollution, during morning fallout surveys along the coastal highway. Some shearwaters are alive (left) and are transported to rehabilitations facilities, but most are found dead (right) from vehicle collisions. Offshore islands (right) host tens of thousands of Wedge-tailed Shearwater fledglings attempting to navigate to sea from their underground burrows.
Solutions based on science
Since 2011, annual surveys are conducted to quantify Wedge-tailed Shearwater fallout from Kailua to Waimanalo. This year, with the support from Hawaiʻi Pacific University and the Christine Stevens Wildlife Award, Brianna Law and Dr. David Hyrenbach carried out a new study to measure the characteristics of light pollution at locations where shearwaters were found dead on roads. Using a radio-spectrometer, light measurements were captured from 124 shearwater fallout locations, which occurred over the last four fledging seasons (2020-2023). The spectrometer captures a wide range of data about the light fixtures including brightness and color components. Examining these parameters alongside factors, such as the distance to the nearest shearwater colony and the number of breeding pairs attempting to fledge chicks, can help guide successful management strategies for mitigating fallout.
This science will inform future efforts to improve lighting standards that are safe for both humans and wildlife. Effective solutions may involve adjusting the design, color, intensity, and placement of lights. For instance, red and amber lights are less disruptive to wildlife, helping reduce disorientation and attraction. Additionally, directing lights downward and shielding them to focus on specific areas, like pathways or work zones, can limit light pollution. During peak seabird migratory periods, dimming or turning off lights can further minimize disruptions for birds traveling at night.
In 2024, we started collaborating with a lighting scientist with expertise in setting industry standards, Leora Radetsky at Design Lights Consortium. Next, we are seeking funding to conduct novel research on seabird disorientation and replace problematic light fixtures in fallout hotspots with support from U.S. Fish and Wildlife Service and the Department of Defense.
By mitigating light pollution in southeast Oʻahu, we can restore the dark sky ecosystem that many species, like seabirds and sea turtles, rely on to successfully reproduce, while preserving the night sky for our enjoyment.
How can you help?
- Turn off unnecessary outdoor lights in your homes and businesses.
- Close blinds or curtains to cover windows at night.
- Keep pets indoors or leashed to reduce interactions between them and shearwater fledglings.
Found a seabird grounded by lights? Learn how you can help save them! Oikonos has created an informational post card for you to learn how to help seabirds survive fallout! Click here to learn more.
Watch this video to learn what to do if you come across a fallen seabird!
Who else is affected by light pollution?
Learn more about other Hawaiian seabirds affected by light pollution by clicking here.
Migratory Land Birds
Introduction to ecological impact of artificial light from Design Light Consortium
Sea Turtles in Hawaiʻi
Florida and around the world need dark skies for the hatchlings to navigate safely and quickly to the ocean.
October 31st, 2024
Written by: Brianna Law