West African black rhino
The rarest of the black rhino subspecies, the West African black rhinoceros is currently recognized as "critically endangered," but researchers fear it may be extinct. The species was once widespread in central Africa, but the population has been in decline due to poaching. By 1980, the population was in the hundreds, and by 2000 only an estimated 10 rhinos remained. A survey of the animal's last remaining habitat in northern Cameroon failed to find any of the rhinos, but search efforts continue. No West African black rhinos are known to be held in captivity.