Today is World Rhino Day - but it's a bittersweet celebration for Sudan, the last living male northern white rhino.
Sudan, who lives under 24-hour protection from poachers at a reserve in Kenya, is one of only five living northern white rhinos in the whole world. He has his horn regularly filed down to deter poachers.
At 42, the elderly male's hind legs are weak and his sperm quality is poor, but the future of the entire species rests with him.
Conservationists' attempts at successful mating between Sudan and the two female rhinos at the conservancy have been unfruitful. His female companions have fertility problems of their own, which means artificial insemination hasn't worked either.
Rhinos were a common sight across Africa and Asia at the beginning of the 20th century with an estimated population of 500,000, but poaching for horns has driven three out of the five rhino species to the brink of extinction, according to the International Union for the Conservation of Nature (IUCN) Red List.
In South Africa during 2014 alone, a staggering 1,215 rhinos were killed by poachers - the equivalent of one every eight hours.
Data published by the South African Department of Environmental Affairs (2015)
The western black rhino was declared extinct by the International Union for Conservation of Nature in 2011.
To find out what you can do to help and the conservation efforts of work of Save the Rhino, click here.