London: White rhinos are on the verge of extinction as it is unlikely that their last male member would father an offspring, conservationists say.

The world's only remaining male of his kind, 42-year-old Sudan, is counting his days under armed protection to guard him from poachers, Daily Mail reported.

"Sudan is quite an old animal as far as rhinos are concerned – he is an old animal and going to die soon, I think that is the reality," said Richard Vigne, the chief executive of Ol Pejeta Conservancy – a 90,000-acre not-for-profit wildlife conservancy in Central Kenya.

"The quality of Sudan's sperm is not particularly great. His ability to mount a female is almost non-existent due to problems with his back legs. It was always going to be a shot in the dark. We had the last remaining potentially reproductively viable northern whites left in the world and to recover a species from that level was always going to be a long shot," he said.

Sudan was caught in the Shambe region when he was just one-year-old and shipped to the Dvur Kralove Zoo in the Czech Republic.

In December 2009, he was moved to the Ol Pejeta Conservancy with two female northern white rhinos and another male, for a 'Last Chance To Survive' breeding program.

Three of the five northern white rhinos left in the world lived at Ol Pejeta and it was hoped Sudan would be able to mate with the females Fatu, 15, and Najin, 25, but so far all attempts have failed.

The other remaining male has now since passed away – meaning that as the last remaining male in the world, the fate of the species rests solely on Sudan's shoulders.

The majestic animal is under guard 24-hours-a-day to protect him from poaching, and his horn has been filed down to further lower the risk of attack.

(IANS)