An infant gorilla hand-reared at Bristol Zoo Gardens now has a surrogate mother following a successful introduction.
Western lowland gorilla Hasani was born at the zoo in August.
He was cared for by keepers because his birth mother, Kala, struggled to look after him, despite several attempts at reintroductions.
He has now settled with his new mother, Kera. Curator of mammals Lynsey Bugg said: "It is an amazing achievement."
She added: "We have taken a young gorilla that would otherwise have died and turned him around and he is back with his fellow gorillas inside of a year."
Hand rearing the baby gorilla meant a team of six people taking it in turns to be with him around the clock for seven months, during which he needed feeding up to eight times a day.
Two months ago, keepers reintroduced him to his mother hoping that she would be able to care for him, but she "continued to show the worrying signs of not being able to cope".
Keepers then turned to 16-year-old Kera to see whether she could take on the role of surrogate mother.
A close eye was kept on the pair as introductions were made, with keepers ready to step in if things did not go well.
To the keepers' delight, Hasani and Kera "seemed to get on very well".
It is the first time Kera has taken care of an infant as she was too weak to look after her own baby Afia, who was delivered by Caesarean section five years ago.
Afia was looked after by a surrogate mother Romina when Kera became ill.
"Although Kera had no rearing experience, she is very intelligent and we have been able to nurture her behaviour," Ms Bugg said.
"She has seen several other females rear their youngsters and so had a good foundation on which to build on."
Hasani, who spends every day and night with Kera, will remain close to his surrogate mother for the next three to four years, as he learns to become more independent.
He is one of the zoo's eight Western lowland gorillas that are part of an international breeding programme to safeguard the critically endangered species.