Zookeepers in Japan have learned that no matter how hard you try and no matter what some Arnold Schwarzenegger movies tell you, two males can’t have offspring.

Image via Sapporo Zoo.

In what seems like an article taken straight from The Onion, staff at Maruyama Zoo in the northern city of Sapporo spent four years trying to get two spotted hyenas to mate, only to find out that they were both males. The zoo said in a statement that they received Kami and Kamutori, as a “male and female pair” as part of an exchange with a South Korean zoo in 2010, and they never double checked that.

“We have attempted to house them together for breeding many times but they often fought against each other and never engaged themselves in breeding behaviour,” the statement said.

Not only were the two not getting along or engaging in breeding behaviour, but they actually acted like 2 males – fighting over territory.

“They remained confrontational, leaving bite marks on each other,” one of the zookeepers told Japan Real Time.

Eventually, the zoo said enough is enough and analyzed the two hyenas to figure out their sex. Apparently, that’s really hard to do; only after hormone checks and ultrasound scans of their genitalia from the Hokkaido University were they able to finally say that they are both males. The zoo said that while it was surprised by the results, it had never ruled out the possibility that both hyenas were male given that the two animals never really got along.

The two hyenas are now living in separate cages and the zoo is considering getting an actual female to start their breeding program.