An endangered northern white rhino has died in Kenya, a wildlife conservancy has said, meaning only six of the animals are left alive in the world.

Suni, a 34-year-old northern white, and the first of his species to be born in captivity, was found dead on Friday by rangers at the Ol Pejeta Conservancy near Nairobi. While there are thousands of southern white rhinos in the plains of sub-Saharan Africa, decades of rampant poaching has meant the northern white rhino is close to extinction.

Suni was one of the last two breeding males in the world as no northern white rhinos are believed to have survived in the wild. Though the conservancy said Suni was not poached, the cause of his death is currently unclear.

Suni was born at the Dvur Kralove Zoo in Czech Republic in 1980. He was one of the four northern white rhinos brought from that zoo to the Ol Pejeta Conservancy in 2009 to take part in a breeding programme.

Wildlife experts had hoped the 90,000-acre private wildlife conservancy, framed on the equator and nestled between the snow capped Mount Kenya and the Aberdare mountain range, would offer a more favourable climate for breeding.

The conservancy said in a statement: “The species now stands at the brink of complete extinction, a sorry testament to the greed of the human race.

“We will continue to do what we can to work with the remaining three animals on Ol Pejeta in the hope that our efforts will one day result in the successful birth of a northern white rhino calf.”

Suni’s father, Suit, died in 2006 of natural causes, also aged 34.