Mountain Gorillas Commonly Adopt Young Orphaned Apes

An analysis of 53 years of data on the Gorilla Fund's Karisoke Research Center's mountain gorillas in Rwanda revealed that gorillas in the wild adopt motherless mountain gorillas to keep them safe and reduce their risk of losing their social rank.

For instance, Science reported that four female mountain gorillas four years ago left their infants when their mate got sick. Perhaps they have sensed that their offspring would have a higher chance of surviving with their ailing father as new males often kill unrelated infants from other groups.

To the surprise of the scientists, they found that the infants' uncle, a gorilla named Kubaha, have started taking care of the infants. Tara Stoinski, a primatologist and chief scientist of the Dian Fossey Gorilla Fund said that this behavior is surprisingly common in mountain gorillas.

Gorillas Form Social Groups To Protect Orphaned Young Apes

Behavioral ecologist Matthew Zipple of Duke University said that young chimpanzees, baboons, and monkeys rely on their mothers for support and they tend to die young if they lose their mothers at an early age. But even if they survive into adulthood, they tend to have lower social rank and produce fewer offsprings.

But that seems not to be the case among orphaned young mountain gorillas. Stoinski and her colleagues in Gorilla Fund found that gorillas in the wild would form a social group that has evolved to protect orphaned infants from the ill effects of losing their mothers.

The researchers compared the reproductive success and social rank of orphaned infants to nonorphaned gorillas and found that motherless mountain gorillas are at no greater risk of dying and suffered no long-term effect on reproducing or on their social rank.

The researchers reported their findings of the study, entitled "Social groups buffer maternal loss in mountain gorillas," in eLife on March 23, 2021.

In a separate study about bonobos and other species, researchers found that "Two wild female bonobos adopted infants from a different social group at Wamba."

The findings suggest that altruistic behavior is not exclusive to humans and that fathers also play a significant role in raising young primates, said Duke behavioral ecologist Susan Alberts.

Male Gorillas Love Taking Care of Young Apes

Northwestern University anthropologist Stacy Rosenbaum said that a silverback mountain gorilla named Isabukuru that lived in Rwanda was very fond of an infant ape named Mushya.

Isabukuru would usually pick up and groom Mushya, and get him to interact with him even though it is clear that Mushya would rather be playing with his age-mates. Experts would often describe this behavior as babysitting.

Contrary to popular belief that male gorillas are aggressive and chest-thumping animals, experts said that male gorillas are very gentle and loving towards infants in their group. They are described as incredibly tolerant to infants and even cuddle and play with them, The Atlantic reported.

"They'll let the infants do things to them that they wouldn't let even a subadult get away with. It's certainly not the stereotypical image you have of male mountain gorillas," Fossey said.

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