The last known male northern white rhino on Earth is under heavy guard in Kenya as conservationists struggle to save the species from certain extinction.

His name is Sudan, and he is only one of five remaining northern white rhinos in the entire world. And after the recent deaths of two male rhinos - named Suni and Angalifu - back in October and December, respectively, his role in his species' survival is now paramount.

The hope is that Sudan will mate with one of the remaining white rhinos brought to the Ol Pejeta Conservancy in Kenya in 2009 - females Najin and Fatu (Suni was also among the bunch before he died). However, until that happens, this big guy is being watched over 24/7 by four armed rangers to protect him from poachers.

The conservancy reached an agreement with the Dvur Kralove Zoo in the Czech Republic to bring these four white rhinos to a more natural habitat in order to boost their odds of successfully reproducing naturally. And while the move has its benefits, it also puts the rhinos at risk of being killed by poachers by being kept outdoors.

Last year alone, approximately 1,215 of these mammals were killed by poachers in South Africa, reaching an all-time record - that's about 100 rhinos a month.

Poachers target rhinos for their keratin horns, which are highly valuable, especially in China, where they are claimed to have medicinal value. And the demand for rhino horn is so high that poachers have started to use increasingly sophisticated technology to capture and kill rhinos, and national parks cannot keep up. (Scrol to read on...)

However, fear not for Sudan, for has he roams the 3,229-square-foot conservancy, not only are armed guards keeping watch, but other measures have been taken to protect him.

"Because of the poaching crisis, one of the measures was to remove horns," Richard Vigne, CEO of Ol Pjeta, told ABC News. "Not all of it, but hopefully enough to reduce their attractiveness for poachers."

While these precautions are indeed helpful, it seems that time may be the real enemy. Sudan is 42 years old, and the northern white rhino, one of the most endangered sub-species in the world, often lives between 35 and 50 years of age, according to the World Wildlife Fund(WWF). Sudan has already outlived Suni, who died at age 34, while Angalifu, who was at the San Diego Zoo Safari Park, died at age 44.

Wildlife conservationists are hoping that Sudan and females Najin and Fatu will mate naturally, in-vitro fertilization may be the only option left. But this method may compromise the species' genetic identity, as it may require a southern white rhino surrogate mother.

"Consequently the species now stands at the brink of complete extinction, a sorry testament to the greed of the human race," the Ol Pejeta Conservancy said in a statement.

These rhinos officially became critically endangered in 2006, after field surveys revealed that there were only four wild northern white rhinos left in the world, grazing along the African savannah woodlands south of the Sahara. However, that wild population has not been seen since 2005, and experts believe that it is safe to assume that the sub-species is now extinct in the wild.

So the fate of this rare species now lies in the hands of the three captive rhinos left at Ol Pejeta Conservancy. And as the last known breeding male white rhino, everyone - especially the armed guards - will be watching over Sudan with bated breath.

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