Dung beetles navigate better under a full moon

February 5, 2019, Lund University

Of all nocturnal animals, only dung beetles can hold their course using polarized moonlight. Researchers at Lund University in Sweden have now shown that beetles can use polarized light when its signal strength is weak, which may allow them to find their bearings when artificial light from cities swamps natural moonlight.

"Our investigation reveals that these beetles would be sufficiently sensitive to orient themselves underneath a light-polluted city sky during a full moon. But they would be lost during a quarter or crescent moon," explains James Foster, researcher at the Department of Biology at Lund University.

Moonlight becomes polarized when it strikes particles in the upper atmosphere on its journey to Earth. In the study, the researchers show that the strength of this polarized light signal changes depending on the moon's phase. Polarized light from a quarter moon is only one-third as strong as at full moon, and just one-fifth as strong for a crescent moon.

"This is the very first evidence that the polarization of skylight changes over the lunar cycle," says James Foster.

Together with colleagues in Lund, Germany, South Africa and the U.S., he tested how dung beetles cope with this weak signal at night when using polarization as their compass to roll a dung ball in a straight line across the African savannah. On clear nights, they perceive this polarized light in a blue sky like humans observe on a sunny day—but thousands of times darker.

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Full Moon Lures Ferocious Muskie Fish to Bite

By Tia Ghose, Staff Writer | May 28, 2014 05:00pm ET

Wikipedia

Werewolves and vampires aren't the only creatures likelier to bite during the full moon.

The best time to catch a muskie, one of the country's largest and most ferocious fish, is during a full or new moon, new research has found. The new study provides scientific backing to decades of fishing lore.

Big fish

The muskellunge (Esox masquinongy) is the largest freshwater fish in North America and can grow as long as 6 feet (1.8 meters) and weigh up to 70 lbs. (32 kilograms).

Continued

Sharks Dive Deep Under Full Moon

Megan Gannon, News Editor

Date: 15 April 2013 Time: 05:33 PM ET

A full moon and warm waters may send some sharks diving deep, according to a new study.

Over the course of nearly three years, researchers from Australia observed 39 mostly female grey reef sharks (Carcharhinus amblyrhynchos) living near coral reefs in Palau, Micronesia, east of the Philippines.

Gray reef sharks (Carcharhinus amlyrhynchos)

at Kure Atoll in the Papahanaumokuakea

 Marine National Monument, Hawaii. 
CREDIT: P. Ayotte 

In the winter, the sharks stayed closer to the surface, at an average depth of 115 feet (35 meters), where water was consistently warmer, the team found. Meanwhile, the sharks plunged deeper in when seasonal temperatures started rising in the spring, averaging depths of 200 feet (60 meters).

The sharks also changed their behavior in sync with the lunar cycle, diving deeper during the full moon but sticking to the shallows with the new moon. Previous tagging studies showed that other open-water predators — including swordfish, yellowfin and big eye tuna — also go to greater depths as the lunar cycle progresses. This suggests the moon's brightness might sway the movements of many big fish.

And the sun seemed to have an effect, too; the sharks hit their greatest depths at midday when the most sunlight broke through the water column and began floating back up to the surface in the afternoon. 

Continued:  http://www.livescience.com/28725-shark-dive-full-moon.html

Lions 'more likely to eat people after a full moon'

Other predators, such as wolves, may also be at their most dangerous when the moon starts to wane.


The discovery, from an African study of 500 lion attacks, could explain the full moon's place in folklore as a harbinger of evil or disaster, and its association with werewolves and vampires.

Scientists studied records of nearly 500 lion attacks on Tanzanian villagers between 1988 and 2009.

In more than two thirds of cases, the victims were killed and eaten. The vast majority of attacks occurred between dusk and 10pm on nights when the moon was waning and providing relatively little light.

Lions hunt most successfully when darkness allows them to surprise their prey, but on bright moonlit nights they might have to go hungry.

The period immediately following a full moon provides a lion with a welcome opportunity to catch up on missed meals.

As the moon wanes, it does not appear until well after dusk, which near the equator occurs early even in summer.

Peak danger times for humans are therefore the active hours after sunset, especially the day after a full moon.

The pattern emerged clearly when the researchers compared attack rates with moon phases. Attacks were a third more frequent during the second half of the cycle, when there was little or no moonlight.

Chief investigator Dr Craig Packer, a lion expert based at the University of Minnesota College of Biological Sciences in the US, said: ''People start out at moderate danger during days 0-4, when the moon is only a sliver and sets shortly after sunset.

''Danger then declines as the moon gets brighter each evening, with very few attacks in the nights just before the full moon. Then, wham, danger spikes as those hungry lions can now operate in darkness for the rest of the lunar cycle.

''The post-full-moon spike is restricted to relatively few hours of full darkness before the largish moon rises later in the evening.''

Lion attacks also increased during the rainy season, when the moon was more likely to be obscured by clouds.

The study, published today in the online journal Public Library of Science ONE, involved checking measurements of lion belly size logged regularly since 1978, and records of lion attacks kept by Tanzanian government authorities.

The researchers wrote: ''These findings provide novel insights into human attitudes towards the moon.''

They pointed out that humans have lived close to large nocturnal carnivores for many thousands of years.

Lions were once the most widely distributed mammal in the world, and jaguars, tigers and leopards have co-existed with people in Asia, Africa and tropical America. Human ancestors painted lifelike pictures of lions on cave walls 36,000 years ago.

''Thus we have always been exposed to risks of predation that cycled with the waxing and waning of the moon,'' said the scientists.

Between sunset and sunrise, humans were most active in the evening and at greatest risk from predators.

The researchers added: ''The darkest hours in the early evening are restricted to the weeks following the full moon, and lions are hungriest immediately after the bright evenings of the second quarter.

''Although we are safest from lion attacks during well-lit nights, the full moon accurately indicates that the risks of lion predation will increase dramatically in the coming days. Thus the full moon is not dangerous in itself but is instead a portent of the darkness to come.''

http://www.telegraph.co.uk/news/newstopics/howaboutthat/8650299/Lions-more-likely-to-eat-people-after-a-full-moon.html

Amphibians mate under a full Moon

Amphibians around the world synchronise their mating activity by the full Moon, researchers have discovered.

This global phenomenon has never been noticed before, but frogs, toads and newts all like to mate by moonlight.

The animals use the lunar cycle to co-ordinate their gatherings, ensuring that enough males and females come together at the same time.

In doing so the creatures maximise their spawning success and reduce their odds of being eaten.
Details of the discovery are published in the journal Animal Behaviour.

Biologist Rachel Grant of the Open University was studying salamanders near a lake in central Italy for her PhD in 2005 when she noticed toads all over the road, under a full Moon.

"Although this might have been a coincidence, the following month I went along the same route every day at dusk and found that the numbers of toads on the road increased as the Moon waxed, to a peak at full Moon, and then declined again," she says.

A review of the scientific literature found little mention of any similar records, so Grant returned to the same site in 2006 and 2007 to survey the amphibians in more detail.

She then collated her data with a 10-year analysis of the mating habits of frogs and toads at a pond near Oxford, UK, collected by her supervisor Tim Halliday, and with data on toads and newts living in Wales collected by colleague Elizabeth Chadwick from Cardiff University, UK.
"We analysed the data, and found a lunar effect at all three sites," Grant says.

For example, the common toad (Bufo bufo) arrives at all its breeding sites, mates and spawns around the full Moon. The common frog (Rana temporaria) also spawns around the time of the full Moon.

"Newts also seem to be affected by the lunar cycle but the results are less clear," says Grant.
Newt (Lissotriton vulgaris, L. helveticus and Triturus cristatus) arrivals peak during both the full and new moons.

But "newts appear to avoid arriving at the breeding site when the Moon is in its third quarter. This could be because the Earth's magnetic field is highest at that time. More research is needed to clarify this," Grant says.

The researchers have also looked at historical data collected in Java on the Javanese toad (Bufo melanostictus) and found that it too mates by the lunar cycle, with females ovulating on or near to the full Moon.

"We now have evidence of lunar cycles affecting amphibians in widespread locations. We definitely think that Moon phase has been an overlooked factor in most studies of amphibian reproductive timing," says Grant.


"We think this may be a worldwide phenomenon. However, differences between species in ecology and reproductive strategy may mean that not all amphibians are affected in the same way. This is something we would like to investigate further."

Grant and her colleagues now hope to produce a statistical model that takes into account weather factors and other environmental variables such as geomagnetism, as well as the lunar cycle.

Making accurate predictions of mass amphibian movements is important in their conservation, she says. For example, roads could be closed at precise times to avoid cars killing thousands of mating frogs and toads.

"Given the current global crisis among amphibian populations, further understanding of [their] breeding behaviour is extremely important," she says.





Matt Walker Editor, Earth News


http://news.bbc.co.uk/earth/hi/earth_news/newsid_8145000/8145125.stm