Study: Full Moon Dictates When Lions Attack

In folklore, literature and film, a full moon usually means the wolves will be out to play and hunt.

In real life? It's the lions that love the days after a full moon.

A recent study from Craig Packer, an international lion expert based at the University of Minnesota's College of Biological Sciences, says a full moon represents impending feast time for the lions. Bright lights limit the lions' hunting success. However, Packer says, the day after a full moon, when the sky is darkest at night is prime time for the lions.

Packer and his cohorts conducted a study of nearly 500 lion attacks on Tanzanian villagers between 1988 and 2009. Of the 500 attacks, two-thirds were fatal and the majority occurred between dusk and 10 pm. Most attacks occurred on nights when the waning moon provided little light.

The research team used several data points to reach this conclusion. They studied measurements of belly size recorded at regular intervals since 1978 in the Serengeti and Ngorongoro Crater, looked at lunar cycles since then and looked over the reported attacks on human in the area.

While lions can attack wildlife at any time, humans are typically most active around dusk to 10 pm. This is why the moonless nights are the times lions are most active in attacking, because on those darker nights they can go after humans.

Packer and company actually quantified it.

So people start out at moderate danger during days 0-4, when the moon is only a sliver and sets shortly after sunset, Packer said in a statement. 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.

Since lions were once the most distributed carnivore on the planet, the moon's significance in those folklores may have evolved from the reality.

The attacks have actually dropped off due to attacks from the nearby villagers.

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

The paper written by Packer will appear in the July issue of PLoS One.