Officials at the Japanese zoo where Momo the gibbon lives were baffled when she fell pregnant two years ago. They were unsure of how the 12-year-old gibbon, who lives alone in her enclosure, could have become pregnant. Now the mystery has been solved with the help of DNA evidence.
There are neighbours for the female white-handed gibbon, but two obstacles stand between them. Zookeepers found it challenging to comprehend what had transpired as a result. They made multiple attempts over several years to obtain DNA samples from the male gibbon she gave birth to in 2021. However, Momo refused to allow them to get close enough to gather the samples because she was understandably protective of her child.
At last, samples were obtained not only from Momo's son but also from Momo and four nearby potential fathers. With the results in hand, they can declare with certainty that 34-year-old Itoh, an agile gibbon, is the father.
Staff at the Kujukushima Zoo & Botanical Garden still had to figure out how the gibbons managed to mate, despite one mystery being solved by DNA. Although the incident is not captured on camera, zookeepers suspect that a tiny perforated board dividing Momo's enclosure from an exhibition area is to blame.
In the morning and afternoon, Momo and Itoh alternately enter and exit the exhibition area. The board has nine-millimetre holes, but its purpose is to stop mating. Amazingly, employees think that's how they were able to have children.
According to zoo superintendent Jun Yamano, "We think it's very likely that they copulated through a hole on one of the days that Itoh was in the exhibition space."
Itoh would have had to jump through a few hoops to get Momo's attention. The staff is shocked by what happened in part because gibbons are known to be picky when it comes to mate selection. These monogamous animals choose their partners through complex vocalizations, social behaviour, and appearance.
Now that the zoo has the complete family photo, they are gradually attempting to get Itoh to accompany Momo and her son. "They must first acclimate to one another. However, ideally, they coexist as a single family," Yamano said.