Zookeepers try to mate hyenas for years, only to find out both are male
For years, zookeepers in Japan tried to get two spotted hyenas to mate and reproduce, but with no success.
Instead of being attracted to each other, the hyenas often fought.
It was only recently that zookeepers discovered the reason for the lack of interest: Both hyenas are male.
The Maruyama Zoo in Sapporo said in a statement this week a South Korea zoo gifted the two animals to them in October 2010 as a "male and female couple".
"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.
Undergo sex tests
Kami, the supposedly female hyena, showed no estrus symptoms after reaching sexual maturity. This prompted the zoo to put it and its partner Kamutori to sex tests.
"We have determined that the two animals are both male after conducting ultrasound imaging and hormone tests on them under anaesthesia," the statement said.
Kami is five years old, while Kamutori is six years old.
The zoo explained that it is "extremely difficult" to determine the sex of a spotted hyena from the appearance of its external genitalia.
"We still plan to obtain a female spotted hyena for breeding with either Kami or Kamutori," the statement said.