Tuesday, July 27, 2010

Keeping Sea Turtles in the Dark

We are so happy to greet the scores of sea turtle hatchlings emerging from their nests on beaches across Antigua. Between February and June, the giant leatherback turtles arrive to nest on our beaches, and throughout the summer, we wait in anticipation of the tiny hatchlings. But while there is great anticipation for the hatchlings, there are also great challenges that these hatchlings will face, particularly on beaches with bright lights.
In natural conditions, where beaches are dark throughout the night, turtle hatchlings will instinctively head towards the “glow” of the sea. However, on beaches with artificial lighting, this first step in a hatchling’s life is not so easy. On beaches with visible lighting from buildings, gardens, or streetlights, hatchlings will instinctively crawl towards the light, often converging under the light source. Lights can also attract hatchlings into thick vegetation, across roadways, into the path of predators, and unless rescued and returned to the sea, they can die within hours.
Fortunately, there is a lot that can be done to help minimize the risks for these hatchlings. Following these best practices for lighting can make a big difference for sea turtle survival:

§ Keep the Lights LOW – The most visible lights (from the beach) are lights mounted high on buildings or poles. In many cases, simply lowering the height of the light may solve the problem. Lowering and directing light to precisely where it is needed can also be more aesthetically pleasing, more functional, and more energy-efficient.

§ Turn Lights OFF in peak times – Restrict usage or extinguish lights during peak sea turtle nesting and hatching seasons, and especially during peak hatching hours (typically 7-11 PM) when hatchlings are most likely to emerge from their nests.

§ Use Directional Fixtures – Some lights, such as carriage lights or globe lights, disperse light in every direction. Be thoughtful about your lighting! Do you really need to illuminate (and pay for!) the entire night sky? Directional fixtures can focus the light downwards and away from areas visible from the beach.

§ Shield Lights – Shielding an open light source may reduce the amount of light directed onto the beach. Simple screens (such as the use of aluminum flashing) or planting vegetation (such as an ornamental hedge) can effectively shield lights. Be creative! Soften lights with locally-made basket shades. If shielding is impractical, then these lights may need to be substituted with lower, directional lighting.

§ Use Motion Sensitive Lights – When night-time lighting is indispensable, particularly from a
security standpoint, installing lights with motion detectors reduces their detrimental effect on sea turtles because of the relatively brief duration of their illumination. Moreover, motion sensitive lighting carries the element of surprise, conveying a distinct advantage to posted guards who remain in the shadows. Motion-lighting provides light only when necessary, and is ideal for lowtraffic areas.

§ Remove Unnecessary Lights – Lighting inspections may determine that some lights are unnecessary or redundant and can be removed or turned off, saving money and benefiting both ambiance and sea turtles. Try to avoid the use of purely decorative lighting, such as lights that highlight vegetation, in places that can be seen from the beach.

§ Invest in Alterative Light Sources – Sea turtles are less sensitive to certain types (and colors) of lights. All metal hyalites can have adverse effects on sea turtles and should be replaced as a priority. High pressure sodium vapor lights also strongly affect sea turtles, and should only be used in areas not visible on the beach. Incandescent lights have moderate effects on sea turtle behavior, except for “bug lights” which are tinted yellow. Low pressure sodium vapor lights (LPS) are the least detrimental to sea turtles. Monochromatic yellow in color, LPS lights have the longest wavelengths, which sea turtles do not detect as readily. The best choice, if light is necessary, is often LPS lighting.

The Antigua Sea Turtle Project is happy to assist anyone who is interested in making their beachfront lighting more turtle-friendly. This will ensure a better chance for dozens of hatchlings, especially on active turtle nesting beaches. If you should find hatchlings heading far away from the sea or disoriented (e.g. under a light, in a garden, in the road) please:

- Turn off or shield any sources of light and remove physical obstructions that may be distracting and allow them to naturally find the sea
- If hatchlings will not enter the water, or disoriented hatchlings are found in the day time, contain them in a bucket or box and contact the EAG Sea Turtle Project at 720 6955 immediately for assistance


Unknown said...

Great article! We reposted on our facebook page for South Florida! Thank you from our turtles!. SeaTurtleOP.org

Unknown said...

Excellent Information.
Your article show us many important line for sea turtle friendly lights