The white rhinos left in the world have drastically gone down to six. The shocking news of the number of white rhinos left in the world came after Suni, a 34-year-old northern white rhino, was found dead by rangers in his enclosure in Kenya's Ol Pejeta Conservancy on Oct. 17.

Experts said Saturday that the rare species is now extremely close to extinction. Suni has unfortunately not fathered any offspring, although he is considered one of the only two remaining breeding males of the northern white rhinos left in the world.

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

Suni, a former member of the white rhinos left in the world, was believed to have died from natural causes, the reserve said in a statement. White rhinos are known to live for up to 40 or 50 years.

An autopsy is set to be carried out later this week by vets at the Kenya Wildlife Service. However, officials say they are certain that Suni was not killed by poachers, since the rare animal was being monitored around the clock.

Considered as the first northern white rhino born in captivity, Suni was conceived at the Dvůr Králové Zoo in the Czech Republic in 1980. However, he quickly became one of the two males and two females from the zoo, four of the world's eight remaining northern rhinos, to be sent to the Kenyan conservancy in 2009 .

The reintroduction into the wild of these white rhinos left in the world have reportedly become part of a last-ditch effort to save the critically endangered subspecies, an operation dubbed "the last chance of survival".

It was initially hoped that being in the wild would make it easier for these white rhinos left in the world to breed, and that the hormones of females would normalise. However, it hasn't worked. Even efforts at assisted conception failed, reports the AFP.

"One can always believe in miracles but everything leads us to believe that hope they would reproduce naturally has gone," Jana Mysliveckova, the zoo's spokeswoman, told AFP.

"It's a shame the subspecies got to that point-that's the worst-case scenario in trying to bring back a subspecies," said Matthew Lewis, senior program officer for African species conservation at WWF.

The population of the northern white rhinos left in the world is a "victim of evolution," Lewis said. He added that it was a remnant population cut off from the southern white rhinoceros by the Great Rift Valley and the dense forests of Central Africa.

On a related note, the southern white rhino, a related subspecies, is considered near threatened by the International Union for Conservation of Nature, according to the National Geographic.

Meanwhile, the Conservancy is not entirely giving up hope in saving the population of the white rhinos left in the world.

"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," said the Conservancy.

It's not only the white rhinos, but from African lions to elephants, many of the continent's megafauna species have reportedly drastically decreased in number, mainly because of poaching and several other human causes.

"It also means we're losing this distinctive, important animal within the savanna ecosystem," said Stuart Pimm, a conservation ecologist at Duke University in Durham, North Carolina, who is also a contributor to National Geographic's News Watch blog.

The white rhinos left in the world are essential to keeping grasslands healthy, since they eat and keep in check several species of savanna flora.

"It's not just another charismatic animal-it's also a species that has a very clear ecological role, and we need to be very worried that we have lost that," according to Pimm.

While there are only 6 northern white rhinos left in the world, there are still thousands of southern white rhinos roaming the plains of sub-Saharan Africa, according to The Independent. However, the illegal and destructive act of poaching for several decades has contributed to the radical decline in northern white rhino numbers.

Poaching of northern white rhinos in central and east Africa have been because of the subspecies' horns, highly valued for their role in traditional Chinese medicine. Poachers reportedly ship the stolen ivory to Asia, where last year, rhino horn was valued higher than even gold or platinum.

The white rhinos left in the world may be very few in numbers and already at the brink of extinction, but conservationists are still carrying on and now focusing their efforts to guarantee the safety of these subspecies and stop the demand for rhino horn in Asian countries like Vietnam.