Nabire was a 31-year-old Northern White Rhino who called Czech Republic’s Dvur Kralove Zoo home until her death, which was announced Tuesday. Nabire suffered from uterine cysts, which made it impossible for her to breed naturally, and a ruptured cyst led to her demise. In December 2014, the world’s Northern white rhino population dropped from six to five after the 44-year-old male named Angalifu died at the San Diego Zoo.