White Rhino Dies in San Diego, California Zoo: Only 5 of the Endangered Species Left as a Result of Excessive Horn Poaching

A northern white rhino has died at the San Diego Zoo, leaving just five of these creatures known to be living left and bringing the species even closer to extinction.

Angalifu, a male rhino, died of old age on Sunday at his home in the San Diego Zoo Safari Park. He was 44 years old, CNN reports

"With Angalifu's passing, only five northern white rhinos are left on the planet, including Nola, our elderly female," a statement released by the zoo read.

Park curator Randy Rieches spoke about the tragedy, USA Today reports.

"Angalifu's death is a tremendous loss to all of us ... not only because he was well beloved here at the park but also because his death brings this wonderful species one step closer to extinction," he said.

The late rhino was just one of a small handful of northern white rhinos left in the world, a few of which live at a wildlife conservancy in Kenya. There are no remaining white rhinos left living in the wild. Northern white rhinos and southern white rhinos are genetically unique species and don't often interact.

The International Union for Conservation of Nature said the northern white rhino is "teetering on the brink of extinction." These animals are hunted by poachers for their precious horns, which sell for tens of thousands of dollars on black markets. The demand for this rare product is largely driven by buyers in East Asia, who believe the horn cures many various ailments.

Some experts say rhino horn is becoming a more lucrative illegal trade than drugs, CNN reports. Organized criminal groups have increased their tactics for hunting the large land animals with military-grade helicopters, guns fitted with silencers and night-vision equipment. Their incentives for killing rhinos have left conservationists struggling to protect this dwindling population.

USA Today reports that in San Diego, all attempts to mate Angalify with Nola were unsuccessful.

The Old Pejeta animal sanctuary in Kenya had similar difficulties mating their animals naturally but are now turning to in vitro fertilization methods to try and retain the species' future.