Western lowland gorilla Hasani was born at Bristol Zoo Gardens in western England in August 2020. Yet keepers quickly realized that his birth mother, Kala, couldn’t manage him.
They designed a hand-rearing program, with six staffers on rotation to ensure that Hasani was fed up to eight times a day for a period of seven months.
“We really wanted to get them back together and give Kala another chance to look after him,” Lynsey Bugg, Curator of Mammals, explained in a Bristol Zoo news release.
In March 2021, keepers felt that Hasani was ready for reintroduction, and Kala was interested, but sadly, she continued to struggle with caregiving. After weeks of trying, Hasani’s keepers had to accept that it wasn’t working out. However, they had another idea.
A resident female gorilla, Kera, 16, had had her own daughter, Afia, adopted by a surrogate, named Romina, when she fell ill with potentially fatal preeclampsia after delivering her baby via Caesarean section five years ago.
Yet despite her lack of rearing experience, keepers believed Kera would be up for the challenge.
Describing her as “very intelligent,” Bugg explained, “She has seen several other females rear their youngsters and so had a good foundation on which to build on.”
During Hasani’s hand-rearing, Kera showed an active interest in the infant. Introductions began with the pair touching through an open partition, with keepers on standby. Things went well; they were able to progress to unrestricted access within days.
Finally leaving the two gorillas alone, keepers watched on TV monitors from elsewhere in the gorilla house. “It is a question of using experience and judgment to decide how long to leave them,” said Bugg, who also works as an advisor on surrogacy for the gorillas’ EAZA Ex-situ Programme (EEP).
With Hasani safe in Kera’s hands, the pair were given their own enclosure. On May 20, the zoo confirmed on Facebook that Hasani is now spending every day and night with his surrogate mom, and is making great progress.
For the next three to four years, Kera will show her young charge how to live, thrive, and be independent.
“This is a fantastic success,” said Bugg. The baby gorilla, who may not have made it without his surrogate, is “back with his fellow gorillas inside of a year.”
The next step is for Hasani to meet the zoo’s other resident western lowland gorillas. He has already been close enough to hear their calls, and has met his father, Jock, and has been reintroduced to his birth mother, Kala, successfully.
Bristol Zoo Gardens is home to eight western lowland gorillas as part of an international breeding program to help preserve this critically endangered species. Conservationists from Bristol Zoological Society, the charity that oversees the zoo, are also involved in a gorilla conservation project in Monte Alén National Park, Equatorial Guinea.
According to Bugg, 9-month-old Hasani is a success story.
He’s “starting to copy Kera in natural gorilla behaviors such as nest building and stripping bark and leaves from branches,” she explained. “He will grow up to be a fully-functioning gorilla, thanks to the efforts of his dedicated keepers.”