Zookeepers solve mystery of female monkey who got pregnant while she was alone in her cage

Zookeepers at a Japanese zoo have finally solved the mystery of how a female white-handed gibbon named Momo managed to get pregnant despite living on her own.

Momo who lives at the Kujukushima Zoo & Botanical Garden, in Nagasaki, became pregnant in 2021 and later gave birth to an adorable baby gibbon.

However, staff at the zoo were completely flummoxed over how the solo female - who has an enclosure to herself - came to get pregnant.

In a post on Instagram shortly after the gibbon was born, the zoo admitted that it wasn’t yet sure who the papa was.

The zoo explained: “Just so everyone wants to know ‘who's the dad’ hasn't been found out yet because we haven't done DNA testing, but we found out the gender is male.”

Immaculate conception within the gibbon world? Not quite, because almost two years on staff at the zoo have finally revealed how Momo came to be knocked up.

KUJUKUSHIMA ZOO & BOTANICAL GARDEN/morikirara/Instagram

Explaining why it took so long to solve the mystery, Jun Yamano, the superintendent of the zoo, said: "It took us two years to figure it out because we couldn't get close enough to collect samples - she was very protective of her child.”

Firstly, they carried out a DNA test on the baby and discovered that its dad was Itoh, a male gibbon who was held in a separate enclosure.

But love knows no bounds, and a simple thing such as being housed in a separate unit was not enough to keep Momo and Itoh apart.

Yamano explained to Vice that staff believe the pair were able to mate due to an area next to Momo’s enclosure that both she and Itoh took turns using, while on display to the public.

The investigation found a tiny hole, measuring 9 millimetres in diameter, in the board that separated that unit from Momo’s enclosure.

KUJUKUSHIMA ZOO & BOTANICAL GARDEN/morikirara/Instagram

Although the zoo didn’t manage to capture any footage of the copulation, it’s thought the two gibbons were able to get it on while Itoh was inside the display area and Momo was nextdoor on the other side of the hole. A sort of gibbon glory-hole, if you will.

Yamano went on to say that the mating, and subsequent pregnancy, was unprecedented at the zoo as the gibbons are usually paired together intentionally after being introduced to each other.

They now plan to allow Itoh into the same enclosure as Momo and their baby and have also fixed the pesky hole in the wall.