At the turn of the 19th century, there were approximately one million rhinos. In 1970, there were around 70,000. Today, there are fewer than 24,500 rhinos surviving in the wild. Three of the five species of rhino are “Critically Endangered” as defined by the IUCN (World Conservation Union). A taxon is classified as critically endangered when the best available evidence indicates that it meets any of a range of pre-determined criteria. It is therefore considered to be facing an extremely high risk of extinction in the wild. The southern subspecies of the white rhino is classified by the IUCN in the lesser category of being “Near Threatened”; and the Indian rhino is classified as "Vulnerable"even this is considered to be facing a high risk of extinction in the wild.