For the past four years, park staff have believed that a gorilla kept at the Ohio Zoo in the US was male. But the gorilla has now given birth to a cub. This gorilla named Sully has been living at the Columbus Zoo since 2019. Staff discovered that the gorilla had given birth to a cub. In a blog post, zoo staff said the baby gorilla is in good health and its mother is doing well.

It also stated that the confusion over Sully's gender was caused by the fact that no one had ever caught her and even tested her for sex, as she had always been in good health.  The arrival of this new gorilla cub was completely unexpected, but this new arrival will play an important role in the conservation of this endangered species," the post said. 

Zoo staff said they had no suspicions until they saw the gorilla nursing her cub, adding that "it's very difficult to determine the sex of young gorillas. Although Sully is now eight years old and has the ability to conceive a cub, at this stage she is still a young gorilla, so she has not engaged in activities that reveal her sex. 

"Male and female gorillas are of equal physical size until the age of eight. Until then, their reproductive organs are not developed enough to be seen on the outside. Male gorillas start sexual activity only after the age of 12," zoo staff say. Because gorillas' bellies are naturally very large, when they are pregnant, the cubs in their stomachs are much smaller than human babies, so they are not easily detected. 

"It was a great surprise to see the birth of one more cub of this endangered species," the zoo management said. "Since the first gorilla cub was born in Columbus Park in 1956, 34 cubs have been born so far. The truth is that protecting this great animal is a very important task for us. The park management has decided to conduct a genetic test to identify the father of this newborn baby gorilla.