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A rare sighting of a chimpanzee giving birth in the wild came to a grisly conclusion. Within seconds of the birth, the baby was snatched away and eaten by a male of the same group. The observation explains why female chimpanzees tend to go into hiding for weeks or months when they have their babies.

Little is known about how chimpanzees give birth in the wild because only five births have ever been observed, says Hitonaru Nishie of Kyoto University in Japan. Nishie and his colleagues have been studying chimpanzees in Tanzania’s Mahale mountains for the last few years.

One of the reasons so few have been witnessed is that the soon-to-be mothers often leave the group when the baby is due, and don’t return until the infant is weeks or months old. This absence has been described as a chimpanzee’s “maternity leave”.

So Nishie and his colleague Michio Nakamura were surprised when, at around 11 am one December day, a female member of the chimpanzee group they were observing began to give birth in front of the 20 other members.

As soon as the baby was out – and before the mother had even had a chance to touch it – the baby was snatched away by a male member of the group, who then disappeared into the bush. The researchers found him around 1½ hours later, sitting up a tree and eating the infant from the lower half of its body. He ate the entire body within an hour.

Rare event

This is the first time anyone has reported seeing a newborn chimpanzee cannibalised in this way, says Nishie. He says that his observation provides an obvious clue as to why chimpanzee mothers tend to hide away to give birth.

In this case, the mother may not yet have had a chance to learn about “maternity leave” if it was her first pregnancy, says at the University of Kent, UK. “I would predict that she would go on ‘maternity leave’ next time,” she says.

In fact, when the female chimp did subsequently have another baby (pictured above), she disappeared for a month.

Male animals of many other species are known to kill young infants that aren’t related to them. This allows them to mate with the mother, and to have more of their own offspring in the group. And female chimpanzees have also been spotted killing the infants of other females when resources like food are scarce, says Humle.

The baby chimp may simply have been a source of nutrition to the adult that snatched it, says Nishie.

At any rate, infanticide and cannabilism are extremely rare among chimpanzees, says Hulme. “I work with a chimp community in West Africa, and I have never witnessed any cases,” she says. Humle thinks that such violence may be more likely to occur in larger groups, where there is more competition for resources.