Aha! Zoo Bears Won't Mate Because Both Are Female

A Japanese zoo is learning it might want to check the plumbing more closely the next time it acquires a polar bear cub, CNN reports. Tsuyoshi was brought to the Kushiro Zoo to breed with 11-year-old Kurumi. But when the cub reached reproductive age, he turned out to be she, which explained why Tsuyoshi wasn't making a move on “his” older lady.

But the zoo won't be sending Tsuyoshi away, or even changing her name to the more feminine Tsuyoko, as local residents are wild about the her. It's not an isolated mix-up: Another zoo adopted Tsuyoshi's "brother”—who turns out to be her sister. (More polar bear stories.)