Zookeepers were taken aback when a gorilla they believed to be male gave birth this week.
Eight-year-old Sully, who has been resident at Columbus Zoo in Ohio since 2019, delivered her baby on Thursday.
Staff at the zoo say the infant gorilla appears healthy, and explained that the original confusion was due to Sully always being in good physical health and never having required examination.
The zoo said in a blog post the delivery ‘was unexpected, yet exciting for the care team and important for the conservation of a critically endangered species’.
They added that ‘until about eight, males and females are about the same size, and they don’t have prominent sex organs.
‘Males don’t develop […] their silver backs until 12 or later.’
Pregnancy can also be hard to detect in gorillas given their large abdomens and the fact infants are far smaller compared to human babies.
Experts will now conduct DNA tests to determine the father of Sully’s baby from among a troop that includes three males, aged between six and 39.
The park continued: ‘As the 34th gorilla born here since 1956, when the Columbus Zoo became the first zoo in the world to welcome the birth of a baby gorilla, she’s an important part of our work to conserve these magnificent mammals.’
They added they were confident the new arrival was indeed female: ‘It’s a girl! Our team confirmed that visually and with photographs that were also sent to a primate expert at another leading zoological facility.’
It’s not the only animal birth story to have made headlines this year.
Earlier in January, tourists in California watched on in awe as a 35-foot mother Pacific gray whale gave birth to a calf near their boat.
Excursion leader Gisele Anderson explained it was exceptionally rare to witness a whale birth in the wild, adding the experience had been ‘humbling’.
She said: ‘Just 70 years ago – well within the lifetime of some of these whales – human beings were still hunting whales. The mother is trusting us, a former predator, with her baby.’
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