Lions are most likely to eat humans just after a full moon, latest research shows.
Other predators, such as wolves, may also be at their most dangerous when the moon starts to wane.
The finding, from an African study of about 500 lion attacks on Tanzanian villagers between 1988 and 2009, could explain the full moon's frequent appearance in folklore as a harbinger of evil or disaster, The Times reported.
In more than two thirds of cases the victims were killed and eaten, and the majority of attacks occurred between dusk and 10pm on nights when the moon was waning and providing relatively little light.
There were about 30 per cent more attacks during the second half of the cycle, when there was little or no moonlight.
Lions hunt most successfully when darkness allows them to surprise their prey.
The study, published in the online journal Public Library of Science ONE, involved checking measurements of the belly size of lions and records of lion attacks kept by Tanzanian government authorities.
The heightened danger after the full moon was 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 researchers said: "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."