Have you ever wondered how the natural world is connected to the Moon and the night sky?
Watching a crescent Moon slowly drift westward in the fading light of an evening sky may not be all that scientific, but it does serve as a reminder that perhaps we aren’t the only ones drawn to its movement across the heavens.
Indeed, humankind is just one of many living things touched “By the Light of the Silvery Moon”, as Doris Day sang in the 1953 film of the same name.
The umbilical-chord existence that tethers Earth to the Moon is an incredibly strong bond.
Both Earth and the Moon duet their way around the Milky Way: a bond that’s absolutely crucial for so many species.
How stargazing gets you closer to wildlife
Turtles and the Moon
For the baby turtle after hatching amid the sand, the gaze of its freshly opened eyes focuses in on the moonlight reflected off the nearby sea, acting as a beacon to guide the turtle safely to the water’s edge.
Interestingly, to the ancient Scots, Norse, Polynesians and Native Americans, the shell of a turtle was of enormous interest.
The shell, when viewed from above, was seen to comprise 13 major inner segments and 28 outer segments around the shell’s edge.
These divisions were interpreted as 13 Moons and 28 days, the equivalent to 364 days plus one day of rest.
No doubt you can buy a calendar with turtles on it today; but to them the turtle itself was a 13-month calendar, incorporating 13 Moon cycles a year, each made up of 27–29 days.
Migration and the lunar cycle
Turning to birds, the European nightjar’s migratory pattern is synchronised with lunar cycles.
Aside from the Moon, most songbirds like thrushes and warblers migrate at night, choosing a single star like Polaris - the North Star - for guidance.
They gauge the movement of the constellations relative to the star, thus calculating the direction they need to be travelling.
At night, the air is cooler and calmer too, meaning that birds use less energy on their long migratory journeys.
With the added bonus that travelling under the cover of darkness means less predators.
Moths and light pollution
The moth, like other insects, engages in behaviour known as transverse orientation, navigating by flying at a constant angle relative to a light source, such as the Moon.
However, if the moth were to fly past an outside light, the angle of light relative to the moth changes, confusing the insect’s delicate navigation.
That is why you see them bumping into lights again and again, as if trying to rectify the disorientation.
Entomologists have found that moths are less attracted to artificial lights during the week of a full Moon than the week of a new Moon.
Animal navigation
Plenty of other creatures, including frogs, seals, and dung beetles, use the Moon and stars for navigational purposes.
Indeed, the humpback whale uses several natural aids to navigate, including not just the Moon and stars, but also the Earth’s magnetic fields.
The link that exists between wildlife and the Moon is strong – but it is under threat.
Light pollution is causing increasing disruption, to the point where migrating birds can be unable to navigate properly.
And baby turtles can be drawn in the direction of artificial lighting rather than following the Moon’s light towards the safety of the water.
This article originally appeared in the October 2023 issue of BBC Sky at Night Magazine.
