5 animals that behave differently under the moonlight

Once every spring, a few days after a full moon, Great Barrier Reef corals simultaneously release eggs and sperm. This phenomenon is so spectacular that it can be seen from space.

Not only does the moon’s gravitational pull interact with the sun to cause tidal ebbs and flows (ebbs and flows), but the moon’s orbit around the Earth produces different lunar phases that vary in brightness. Scientists believe that the moon’s light at certain times each spring may signal that conditions are right for corals to release eggs and sperm.

Of course, the lunar cycle indirectly influences the behavior of some animals during high and low tides by excluding them from fertile foraging areas such as coastal tidal flats. However, sunlight reflected from the moon also directly affects animal behavior. For example, moonlight is a resource for animals that rely on sight for foraging. It is a threat to those who are at risk of being killed at night.

A recent study found that moonlight appears to influence the behavior of mammals, even on the floor of a tropical forest, one of the darkest places on Earth.

Footage from camera traps placed in the undergrowth shows that small mammals such as rodents and armadillos appear to be less active on moonlit nights to avoid predators. Correspondingly, the activity of hunters, including ocelot wildcats, slows down.

In other words, moonlight in the tropics appears to create a natural “rest period” for wildlife. However, some species that rely on vision for foraging and predator avoidance, such as the African elephant shrew (Petrodromus tetradactylus), have been shown to have increased nocturnal activity under moonlight.

Here are five animal species from around the world that have interesting behavioral responses to moonlight.

1. African mayfly

Like corals, the mayflies (Povilla adusta) of East Africa’s Lake Victoria mate in synchronization with the moon.

These insects emerge in large numbers from their aquatic larval stage (which lasts 4-5 months) two days after the full moon. This species of mayfly only lives for 1 to 2 hours as a sexually mature adult (adult stage), so they rush to display, mate, and lay eggs before dying. By using the lunar cycle as a timer, you can see if a potential mate is nearby, and moonlight can also help you carry out urgent tasks.

2. Nightjar

The nightjar is a bird that hunts flying insects at dusk and dawn. My research team monitored nightjars (Caprimulgus europaeus) in flight (both foraging and migrating) for a year using accelerometers, a type of motion sensor.

During full moons, nightjars extended their foraging time into the night, presumably allowing them to catch more insects in the moonlight.

These birds stayed in their local areas during the full moon because they had more time to feed. Then, about 12 days after the waning moon, the nightjar, whose feeding opportunities were disappearing during the spring and fall migration seasons, set off on a long-distance flight from Europe to southern Africa and back.

The month also determines when nightjars lay their eggs. These birds incubate their eggs under a full moon, allowing their chicks to have the best feeding conditions when they need it most.

3. Swift

Swifts (Cypseloides niger) nest on remote cliff ledges and crevices in the western United States and Canada. Little was known about their migration until 2012, when scientists used a tracking device called a light-level geolocator to show that swiftlets that breed in the Rocky Mountains migrate to the Amazon in western Brazil.

Scientists already knew that the European swallow (Apus apus) flies continuously for 10 months of the year when it is not breeding, including migrating between Europe and tropical Africa.

In a 2022 study to test whether this was also true for black swifts, scientists fitted the birds with multi-sensor data loggers. Not only did the black swift remain airborne for eight months during migration and wintering, but it also displayed unexpected behavior.

During the non-breeding season, for 10 days before and after the full moon, they rise to high altitudes (3-4,000 meters) after dusk and remain there all night. In contrast, it remained at a relatively low altitude before and after each new moon.

Flight acceleration data shows swifts fly more actively during light hours at higher altitudes compared to when they were flying in the dark, catching more insects before and after each full moon. (and expended more energy).

Fortunately, a lunar eclipse occurred on the night of January 20-21, 2019, during the study, and five swifts soared high in the moonlight. As the moon hid behind the Earth, all the swifts responded by rapidly descending.

4. Barn owl

Barn owls (Tyto alba) come in two colors: red and white. Field voles, their main prey, spot owls more easily in moonlight and react by briefly freezing them.

A 2019 study found that in moonlight, a field vole is significantly more likely to escape if it’s a barred owl.

But if it’s a white owl, the vole will be blinded by the moonlight reflecting off the owl’s wings and will freeze for a longer period of time. Therefore, white owls are more successful at catching voles during full moons than red owls, which means their young are at less risk of starving to death.

5. Dung beetle

The African dung beetle (Scarabaeus zambesianus) collects elephant dung to make balls in which it rears and feeds its young. These balls are then rolled off the dung pile to avoid competition with other beetles. The most efficient way is to escape along a straight line.

After dusk, when the sun and its polarization pattern (which humans cannot see) are unavailable, dung beetles use the darker polarization pattern around the moon to maintain this straight escape route. However, this is much more effective under a full moon.

In a 2003 study of dung beetles, researchers used a polarized camera lens filter to change the direction of the full moon’s polarization pattern, allowing the beetles to change direction.

In contrast, on dark nights around the new moon, the beetles were unable to maintain a straight path and moved along a winding path.

This article is republished from The Conversation under a Creative Commons license. Read the original article.