The Moon and Sea Turtles

The recent "supermoon" received a lot of media coverage over the weekend.  The full moon appeared larger in the sky because it's orbit was closest to the earth, which is called "perigee." "Supermoons" actually occur regularly.  Human nature, however, seems to be attracted to them. People have ascribed all sorts of things to the full moon with very little scientific support (1).

The question we often get is, "do sea turtles come out during a full moon?"  The short answer is they nest and emerge from nests during all moon phases.   Higher nesting in olive ridleys and some loggerhead populations has been correlated to the moon phase, but for the most part factors that affect nesting are unrelated to the moon (2).  However, hatchling orientation can be affected by a new moon.  Disorientation events increase during these times because artificial light sources become a stronger attraction in the absence of moonlight.

Some astrophysicists are frustrated by the media hype surrounding the "supermoon."  Ironically, so are we, but for different reasons.  Over the weekend, our turtle walk scouts witnessed five loggerheads emerge on the beach and then return to the ocean without nesting because of people, no doubt drawn outdoors to witness the "supermoon."  We would like to remind residents and visitors, regardless of the moon phase, that most sea turtles need beaches that are relatively dark and have less human activity in order to successfully nest.

1.  Culver, R., J. Rotton, and I.W. Kelly.  1988.  Geophysical variables and behavior: XLIX. Moon mechanisms and myths: a critical appraisal of explanations of purported lunar effects on human behavior. Psychological Reports, vol. 62, pp. 683-710.

2. Lohmann, K,. B. Witherington, C. Lohmann, and M. Salmon.  1997.  Orientation, navigation and natal beach homing in sea turtles. In: The Biology of Sea Turtles (P. Lutz and J. Musick eds.). CRC Press. New York. pp. 107-135.