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
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