Zookeepers in Japan probably need to get a lesson in biology after spending years trying to mate two spotted hyenas that were both males.
"We have attempted to house them together for breeding many times but they often fought against each other and never engaged themselves in breeding behavior," read a statement from Maruyama Zoo in Sapporo, northern Japan, where the hyenas were being bred.
Hyenas Kami, 5, and Kamutori, 6, were put in the same cage for breeding in 2012, but zookeepers didn't figure out Kami was actually a male until this year, reports The Guardian.
The pair never got along, but zoopeepers never thought it was because of their sex, reports Wall Street Journal.
However, the zookeepers still couldn't figure out why the animals weren't mating, so they eventually decided to give them a sex test using ultra sound imaging and hormone tests on them while under anaesthesia, according to the statement.
Apparantly the hyenas were both males, although the zoo received the pair in October 2010 as a "male and female couple" from a zoo in South Korea.
The Japan zoo defended its zookeepers by explaining "that it is extremely difficult to determine the sex of a spotted hyena from the appearance of its external genitalia."
An actual female hyena is wanted at the zoo to mate with Kami or Kamutori.
