Exploring the Moon’s Significant Influence on the Animal Kingdom…
Numerous intriguing stories have emerged surrounding full moon nights, leading scientists to ongoing debates. Researchers have proposed various hypotheses to unravel the extent of the Moon’s influence on the animal world. Is it a mysterious, mystical power of nature, or merely phenomena that science has yet to explain?
However, in a recent study, biologist Noga Kronfeld-Schor from Tel Aviv University (Israel) indicated that: “The Moon may act as a synchronizing cue between individuals, serving as a signal for other environmental parameters such as tides, food sources, or simply allowing animals to utilize visual cues. The behaviors it influences are quite diverse, ranging from long-term processes like seasonal breeding and migration to direct responses to light levels.”
Let’s explore several ways the Moon’s cycle impacts animal behavior through research from Discovery News.
1. Increased Coral Spawning
In a study of the Great Barrier Reef in Australia, scientists observed that after every full moon, hundreds of coral species spawn simultaneously. Researcher Oren Levy from Bar Ilan University (Israel) stated to Discovery News that the Moon “can orchestrate the spawning of over 130 coral species.”
Through their research, scientists found that the Moon likely serves as the primary stimulus for this phenomenon. The gravitational influence of the Moon on Earth’s fluids (a theory used to explain the tides that often rise during full moon nights) somewhat affects the habitats of various coral species.
Various factors like temperature, salinity, and food availability have contributed to supporting hundreds of coral species in simultaneously releasing sperm and eggs, thereby increasing the chances of fertilization.
2. Pets Become More Aggressive
In an extensive examination at the Colorado Animal Hospital (USA), researchers noted that animals often became aggressive and displayed unusual behaviors during full moon nights.
Commonly, they would bite, scratch, and “gift” each other wounds. Injuries or health conditions in domestic animals closest to humans, such as dogs and cats, also became more severe.
During full moon nights, the number of pets in critical health conditions at emergency veterinary rooms increased by up to 23% (for cats) and 28% (for dogs).
However, scientists believe there is an invisible connection between this time of the month and the behavior of animals that has yet to be explored. One hypothesis suggests that pets may spend more time roaming outside at night when the Moon is bright, thus the Moon’s gravitational pull somewhat affects their nervous systems, leading to increased “biting” behavior.
3. Beetles Dig Larger Holes
The ant lion larvae, a type of beetle, dig larger holes to capture prey during full moon nights.
This behavioral change may result from their insect prey becoming more active under the full moon’s light. Consequently, these beetles diligently dig larger pits in hopes of “harvesting” more prey.
Researchers found that this behavior also occurs in darkness, but it is not as effective as during the Moon’s cycle.
4. Increased Lion Attacks on Humans
Researchers from the University of Minnesota, USA, after analyzing data from nearly 500 lion attacks on villagers in Tanzania, concluded that the period right after a full moon is when lions become most dangerous and a dark time for humans.
Lions typically hunt successfully at night, allowing them to surprise their prey. On bright moonlit nights, lions may face hunger; thus, the time following a waning moon provides an opportunity for them to find plump prey.
Researchers further emphasize: “The full moon is indeed a precursor indicating a spike in predator attacks in the following days. Therefore, the full moon itself is not the most dangerous day; rather, it signals the approaching ‘darkness.’“
5. Birds Increase Hunting Frequency
Certain bird species increase their hunting frequency during full moon nights. For instance, the eagle owl often shows heightened hunting activity on full moon nights. Additionally, the bright moonlight helps birds achieve better vision, allowing them to cover wider areas when hunting at night.
However, some owl species avoid activity on full moon nights, as research has shown that this behavior helps them evade other formidable predators.
Mayflies in Africa
Mayflies (Povilla adusta) in Lake Victoria, East Africa, synchronize their mating activities with the Moon. These insects appear in large numbers following the completion of their aquatic larval stage (lasting 4-5 months), about two days after the full moon. Once they reach reproductive maturity, they only live for 1-2 hours. Therefore, they must quickly display, mate, and lay eggs before dying.
Mayflies use the Moon’s cycle as a clock to ensure that potential mates will be present. Subsequently, the moonlight helps them complete their urgent tasks.
Mayflies cling to leaves along the Otonabee River, Canada. (Photo: Nina Munteanu).
Nightjars
The nightjar is a group of birds that hunt insects at dusk and dawn. Hedenström’s research team monitored the European nightjar (Caprimulgus europaeus) as it flew (both while foraging and migrating) over a year using an accelerometer—a type of motion sensor.
The results showed that during the full moon phase, nightjars extended their foraging time into the night, possibly to catch more insects under the moonlight. During this period, with additional foraging time, they also remained local.
Then, as they entered the waning moon phase lasting about 12 days, when foraging opportunities gradually diminished, nightjars began undertaking long flights between Europe and southern Africa during the spring and autumn migration seasons.
The Moon also determines when nightjars lay their eggs. They prefer their eggs to hatch during the full moon to ensure optimal foraging conditions when the chicks need food the most.
Swifts
Black swifts (Cypseloides niger) nest on ledges and crevices of remote cliffs in the western United States and Canada. Their migration was largely unknown until 2012, when scientists used geolocators to track and discover that swifts breeding in the Rocky Mountains migrate to the Amazon in western Brazil.
Common swifts (Apus apus) fly continuously for 10 months when not breeding, including migration between Europe and tropical Africa. In a 2022 study, to verify whether this also applies to black swifts, scientists equipped them with multi-sensor data loggers.
The results showed that black swifts not only fly continuously for 8 months of migration and wintering, but also engage in a surprising behavior. Ten days around each full moon, during non-breeding periods, they fly at high altitudes (3,000 – 4,000 m) after sunset and remain there throughout the night. However, around each new moon, they fly at relatively low altitudes.
Flight acceleration data indicate that swifts are more active during brighter times, flying at high altitudes compared to flying in darkness. This suggests they catch more insects and expend more energy during the full moon.
Thanks to a fortunate coincidence, a lunar eclipse occurred during a study on the night of January 20-21, 2019, while five black swifts were flying high under the moonlight. As the Moon was obscured by the Earth’s shadow, all of them reacted by rapidly descending.
Black swifts flying in the sky. (Photo: Michael Bolte/Macaulay Library).
Grey Owl (Tyto alba)
The Grey Owl (Tyto alba) has two distinct colors: red and white. Its primary prey, the field mouse, is easier for the owl to spot under the moonlight, often reacting by freezing for a moment. A 2019 study indicated that under moonlight, field mice have a higher chance of escaping from red owls.
However, if it is a white owl, the mice are dazzled by the moonlight reflecting off the owl’s feathers and remain motionless for a longer time. As a result, white owls are more successful than red owls at catching field mice during the full moon, which means their young have a lower risk of starvation.
Dung Beetle
African Dung Beetle (Scarabaeus zambesianus) collects elephant dung and forms it into balls to nourish its young. It then rolls these balls away from the dung pile to avoid competition from other beetles. The most effective way to roll them is in a straight line.
After sunset, when the Sun is absent and its polarized light pattern (invisible to the human eye) is missing, dung beetles utilize a much less distinct polarized pattern around the Moon to maintain a straight path. This method is significantly more effective under the full moon.
In a 2003 study, using polarized camera lens filters, a team of experts successfully altered the direction of the full moon’s polarized pattern, causing dung beetles to change their trajectory as well. In contrast, on dark nights near the new moon, dung beetles struggle to maintain a straight line and instead follow winding paths.
