There's only one male northern white rhino left in the world

The world is down to a single known male northern white rhino, and he is now under 24-hour armed guard.

He's called Sudan, and staffers at the Ol Pejeta Conservancy in Kenya are hoping the 42-year-old is able to conceive with one of the two female northern white rhinos. But given his age, chances are not looking good, and other breeding methods are being explored.

Though the animal lives on a preserve that houses fierce predators like lions and cheetahs, its keepers are most concerned about those of the human variety.

Poachers have already thinned the northern white rhino population down to a handful, and it's not believed that the subspecies being on the brink of extinction will serve to deter future attempts.

What they're after are the animals' horns, which are ground up and sold in Asia as remedies for any number of afflictions.