A Czech zoo says a 34-year-old northern white rhinoceros has died in Kenya, further reducing the world's dwindling population of the critically endangered animal.

Suni was born at the zoo in Dvur Kralove in June 1980. The zoo says Suni was found dead Friday in the Ol Pejeta animal sanctuary. The cause of death wasn't immediately clear, but the zoo ruled out he was killed by poachers.

He was one of the four northern white rhinos that the Czech zoo moved to Africa in December 2009 in an attempt to save the species from extinction. The zoo hoped it could be easier for them to breed there than in captivity.

The zoo said Saturday that Suni was one of seven northern white rhinos left.