‘Handsome’ Hippo at Japan Zoo Turns Out to be Female; Zoo Will Keep ‘Gen-chan’ Name

The Yomiuri Shimbun

10:34 JST, April 24, 2024

OSAKA ― Gen-chan, a 12-year-old hippopotamus that had been kept as a male at the Osaka Tennoji Zoo in Tennoji Ward, Osaka, has turned out to be a female. The zoo announced the news on its staff blog on its website.

Gen-chan was born in March 2012 and arrived from a zoo in Mexico in 2017 at the age of 5. Mexican zoo staff said Gen-chan’s sex was male, and the documents required for importation stated accordingly. In August 2017, the Osaka zoo decided to name the hippo “Gen-chan” after a public contest because of the “male” hippo’s energetic movements. Gen-chan had become familiar to visitors to the zoo.

Hippos generally reach sexual maturity around the age of 10, but the zookeepers had wondered why Gen-chan had not been seen spreading feces to claim territory or making courtship calls to females, as males are known to do.

Because of Gen-chan’s large size, it was difficult to visually confirm the animal’s reproductive organs, so the zoo requested a DNA analysis from an outside research organization this month. On April 16, it was confirmed that Gen-chan was female.

On its blog, the zoo said, “We had no doubt at all” about Gen-chan’s sex since the hippo was treated as a male when sent from Mexico. The blog also said, “In light of the results, we recognize the importance of reconfirming the sex of the animal, and we are determined to ensure that this never happens again.”

The zoo will not change the hippo’s name. A zoo official said: “Her petite, lean face had been a topic of conversation among the zookeepers, saying, ‘He’s a handsome boy.’ Even though we now know Gen-chan is a girl, we’ll keep taking good care of her to ensure her comfort. Please come and meet the female Gen-chan.”