July 21, 2011

Moon Phases Strongly Influence Lion Attacks

If you find yourself alone on the African plains, you may want to be more wary of wild animals, especially just after a full moon. Researchers found lion maulings increased dramatically at this time of the lunar phase when the sky is darkening and the animals are most hungry, The Guardian is reporting.

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 in Tanzania between 1988 and 2009, could explain the full moon's place in folklore as a harbinger of evil or disaster, and its association with werewolves and vampires.

According to the study, published in this week's issue of PLoS ONE, victims were killed and eaten in more than two thirds of the cases with the vast majority of attacks occurring 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.

A waning moon 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.

"So people start out at moderate danger during days 0-4, when the moon is only a sliver and sets shortly after sunset," explains Craig Packer, an international lion expert based at the University of Minnesota's College of Biological Sciences.

"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."

Lions are well-known nocturnal predators, relying on the cover of darkness to successfully hunt. This study helps confirm the long-held belief that nocturnal predators played a key role in human evolution, creating fear of the dark and driving the need for nighttime shelter as well as control of fire.

Lion attacks on humans in Africa increased during the 1990s as civilization encroached on lion territory. But Packer reports that attacks on humans throughout Tanzania have dropped off over the past three years because villagers have killed the big cats to protect themselves and their livestock.

"We may be the last research team to ever collect enough data to publish this sort of analysis," Packer says. "Big cats are disappearing fast all over the world, but their evolutionary impact on our psychology will likely persist forever."


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