Zoo thought Sully the gorilla was male. Then staff found her holding her newborn baby

Sully the gorilla is 8 years old and was thought to be a male.

That all changed when Sully was seen holding her newborn baby gorilla at an Ohio zoo.

“Talk about a surprise twist!” the Columbus Zoo and Aquarium said when announcing the two unexpected developments.

Staff members on the gorilla care team discovered the double surprise early Thursday, July 13, according to a July 19 news release from the zoo.

There were no signs Sully was pregnant, the zoo said, as “gorillas rarely show outward signs of pregnancy because the newborns are smaller than human babies and gorillas naturally have large abdomens.”

Sully has tricked wildlife experts since she was born.

“Veterinarians at the zoo where Sully was born maintained a hands-off approach in their care, as Sully was a healthy baby being well-cared for by her mother,” according to the release. “While Sully was initially identified as male, upon arriving at the Columbus Zoo, Sully was a young and healthy animal and did not need any procedures requiring immobilization that would have led to this discovery sooner.”

It’s tricky to determine the sex of young gorillas because males and females are about the same size until age 8, the zoo said. They don’t start to look “very different” until age 12.

With that said, staff at the zoo believe Sully’s baby is a girl. This was confirmed visually and through photographs sent to a primate expert at another leading zoo, according to the release.

“The infant appears to be healthy, and first-time mom Sully is taking good care of her,” officials said. “The veterinary and animal care teams have not yet approached the infant, giving them time to bond with one another and with the rest of the troop, but will conduct a wellness exam soon.”

The zoo said it will also conduct a DNA test to determine the baby girl’s father.

She is the 34th baby gorilla born at the Columbus Zoo since 1956, when the zoo became “the first zoo in the world to welcome the birth of a baby gorilla,” according to the release.

Western lowland gorillas can live into their 50s under human care, according to the Smithsonian’s National Zoo & Conservation Biology Institute. The lifespan of a wild gorilla is typically 30 to 40 years.

Western lowland gorillas are critically endangered, according to the World Wildlife Fund. Threats to the species include poaching and disease.

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