northern white rhino
Sudan - the last surviving northern white rhino Reuters

The extinction of the northern white rhino is seemingly imminent as the last remaining male lives out his final years.

Conservationists have accepted that the chances of the 42-year old male named Sudan reproducing are very slim. His hind legs are weakening and sperm count lowering as the northern white rhino nears his 50-year average life expectancy.

As the only remaining male, he has been kept under armed guard in the Ol Pejeta conservancy in Kenya. Breeding programmes have proved unsuccessful for the three ton animal, and with him, the northern white rhino species will die out shortly after.

Richard Vigne, CEO of Ol Pejeta Conservancy, told Barcroft Media: "Sudan is an old animal as far as rhinos are concerned - and he's going to die soon. I think that's the reality. It really came to a head with the death of Suni last year, the other remaining male northern white rhino, who was much younger than Sudan.

"These animals have been kept in captivity for a long time and there's been little success at breeding northern whites in captivity. His ability to mount a female is almost non-existent because of his problems with his back legs. It was always going to be a shot in the dark."

Sudan was named after the country he was born in and has been in the Ol Pejeta conservancy since 2009 when he was moved from the Dvr Krlov Zoo in the Czech Republic.

Two of the remaining five northern white rhinos live alongside Sudan – both young females which they had hoped he would successfully mate with.

However, Vigne still has a shred of hope and is looking at artificial insemination or alternatively using a southern white rhino as a surrogate for a fertilised egg.

"The problem with that is the technology to do it is yet to be developed in rhinos, so we have to develop the technology and the ability to do it with rhinos before we try to do it on the last remaining northern whites," said Vigne.

"The chances are the living animals that we have on the planet today will die off and disappear before we are able to develop the techniques to recover the species. But we'll have preserved enough of the genetic material that in the future we could create calves and live animals on the ground.

"There's quite a few cell cultures from the various different rhinos that have existed in zoo conditions which are now in storage. In time, when the science allows it – we could create egg and sperm cells to create an embryo for implantation in a southern white. It's a scientific process referred to as de-extinction."