One of six northern white rhinos left in the world died at the San Diego Zoo on Sunday.
Angalifu was thought to be 44 years old. He came to the park from Sudan in 1990 and had been treated for a range of age-related ailments.
"Remaining members of the species include an elderly female at the safari park, one at a Czech zoo and three in Africa. There were four in Africa until October, when one died. The rhinos were taken there from the Czech zoo in the hopes they would mate better in the wild than in captivity, but the effort has not borne fruit.
"San Diego Zoo also tried to mate Angalifu, at one point sawing off the horns of female rhinos to keep them from fending him off. The animals never reproduced, but the zoo has preserved semen and testicular tissues for future use, if possible.
" 'Angalifu's death is a tremendous loss to all of us,' safari park curator Randy Rieches said in a statement. 'Not only because he was well beloved here at the park but also because his death brings this wonderful species one step closer to extinction.' "
Back in October, we reported on the death of Suni, another male rhino in Kenya. The species is now on the brink of extinction.