The world's last surviving male northern white rhino - stripped of his horn for his own safety - is now under 24-hour armed guard in a desperate final bid to save the species.

Sudan is guarded day and night by a group of rangers who risk their lives on a daily basis as they try to keep the rhino from poachers lured by the rising price of ivory.

But even without his horn, keepers in the Kenyan reserve of Ol Pojeta in fear for his safety.

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Guard: The rangers keep an armed watch around Sudan at all times to deter poachers after his horn

Extreme measures: Rangers have even cut off the rhino's horn - but they fear it won't be enough

Hungry: Feeding time in Sudan's enclosure - he spent most of his life in a Czech zoo

Dangerous: The rangers are aware they are risking their lives to protect the enormous animal

The 43-year-old rhino - who could live until his 50s - is the last chance for any future northern white rhino calves.

Sudan was moved, along with two female rhinos, from a zoo in the Czech Republic in December 2009.

The reserve, which specialises in the conservation of rhinos, was chosen because of its successful breeding programme with black rhinos.

It had been hoped the move would encourage them to breed, but all attempts have been unsuccessful.

The project was dealt a further blow when Suni - the world's only other male, who also lived at Ol Pojeta - died last October.

It left just five northern white rhinos in the world - and the three in Kenya are in particular danger.

Hunted: Rhinos like Sudan have no predators in the wild because of their size - apart from humans

New home: It had been hoped moving Sudan to Kenya with two females would encourage them to breed

Simor Irungu, one of the rangers who guards Sudan, says the team regularly risk their lives to keep him safe.

'With the rising demand for rhino horn and ivory, we face many poaching attempts and while we manage to counter a large number of these, we often risk our lives in the line of duty.'

It is a sad end for a species which used to roam across the heart of Africa - from southern Chad, across the Democratic Republic of Congo and up into Sudan.

Just over half a century ago, there were 2,000 northern white rhinos; but 1984 there were only 15, all in the DRC, according to the World Wildlife Fund.

But then conservationist managed to bring them back from the brink, and bought the population up to at least 30 animals less than a decade later.

Failure: But attempts at breeding have been unsuccessful - and Sudan is now getting old

High value: The price of ivory is now said to be between £40,000 and £47,000 a kilo

But then poaching took its toll, and the entire park was emptied. The last northern white rhinos were spotted in 2006.

Their extinction has been fueled by the growing demand for ivory, which comes in large part from the Far East, where it is believed to be a cure for several ailments.

The price for ivory has risen from between £170 to £541 per kilo in the 1990s, to today's prices of £40,000 to £47,355 per kilo, according to a report by the International Fund for Animal Welfare.

The rangers have taken steps to deter the poachers, but they still fear it may not be enough.

Elodie Sampere explained: 'The only reason his horn has been cut off is to deter poachers.

'If the rhino has no horn, he is of no interest to them.

'This is purely to keep him safe.'

Sad end: Sudan is one of five northern white rhinos left, and a number of them are his descedents

However, keeping them safe is a costly business: the team of 40 cost £75,000 for six months.

It is usually paid for with money made from tourism, but recent instability in Kenya, and fear of Ebola - which is actually thousands of miles away - have kept people away.

So the team at Ol Pejeta is hoping to raise the money through crowd funding .

'Keeping the ranger team safe is expensive,' the appeal reads.

'They are given world-class training, and are kitted out with the latest in equipment and support, from night vision goggles to GPS tracking, to a team of tracking and support dogs....

'Keeping the team funded and equipped is an ongoing challenge.

'We are aiming to raise enough to safeguard the wages for the forty strong team for the next six months.

'This is £75,000. Any which way, every single pound contributed will help secure the rangers, that secure the rhino, for us and for future generations.'