For seven years, a wild animal in Japan misled authorities who did not suspect its true nature.
A large hippopotamus at Osaka Tennoji Zoo was initially believed to be male but turned out to be female. This discovery was made after zookeepers observed the absence of typical male behaviours and conducted a DNA test, which revealed the 12-year-old hippo’s actual gender.
Named Gen-chan, the hippo arrived in Osaka in 2017 from Mexico’s African Safari Animal Park. At that time, accompanying documents incorrectly identified her as male. The zoo’s staff initially did not question these documents, as Gen-chan was still a calf.
As Gen-chan matured, zookeepers noted discrepancies in behaviour, such as the lack of male courtship calls to females and the absence of territorial marking with faeces, typical of male hippos.
A spokesperson from Osaka Tennoji Zoo emphasized the importance of accurately determining the animals’ sex to avoid future errors and stated, “We will keep doing our best to provide a comfortable environment for Gen-chan.”
The zoo has publicly addressed the mix-up on its website, ensuring such mistakes are not repeated. The zoo’s vice director, Kiyoshi Yasufuku, also commented on the incident, underscoring the need for thorough verification of gender identification of zoo animals.
