Zookeepers at Ramat Gan Safari in Tel Aviv recently discovered an unusual penguin pairing. Two jackass penguins, both females, have become lifemates.

“Just like young penguins in the wild, here at the Safari Zoo in Israel, at a certain point during adolescence they pair up in couples and stick together for life,” Sagit Horowitz, spokesperson for the Safari, said.

Suki and Chupchikoni , the young penguin couple, were initially thought by zookeepers to be a male-female pair, and that Chupchikoni, the larger of the two birds, was male.

“Chupchikoni may have been a bit small for a male, but the keepers did not find anything suspicious about ‘him,’” Horowitz explained, adding that “There is no way of telling a male penguin from a female just by looking at them.”

Within the penguin exhibit at the Safari, Suki and Chupchikoni are like any other young penguin couple and live together in a burrow they share with another penguin team. Recently, the young duo has even shown signs they are ready to strike out on their own and build their own nest.

“They started collecting nesting materials for their nest,” Horowitz said.

In fact, nothing about the young couple drew the suspicion of Safari staff until they sent away the penguin’s blood for analysis, as part of a study on gender in their penguin exhibit.

“Much to the keepers’ surprise, the results have shown that Chupchikoni is a female!” Horowitz said, pointing out that while zookeepers had no doubt that Suki was also a female her blood was also tested to confirm her gender.

While same-sex penguin pairings have been discovered in zoos before, the female pairing is a first for the Ramat Gan Safari, and zookeepers appear delighted that the couple has decided to bond.

“There are a few young available males in the exhibit,” Horowitz said, emphasizing that the two females had the option of a number of male partners. “We are certain that they made a choice to be together.”