Among the most ancient of animals, rhinoceroses thrived for millions of years before meeting their most deadly enemy: humans.

During the past century, the rhinos of Africa and Asia have been pushed out of their habitats and hunted nearly to extinction for their horns, which are believed — erroneously — to possess healing properties. Now, thanks to the efforts of conservationists and scientists, the rhinos are on their way back.

With NATURE’S Rhinoceros, wildlife filmmaker Nigel Marven brings you face-to-face with the world’s five species of rhino, each struggling, with varying degrees of success, for their continued survival. For some rhinos, the future may rely on breeding programs, such as at the Cincinnati Zoo & Botanical Gardens, where Sumatran rhinoceros Emi is now nearing the end of her third successful pregnancy, having already given birth to Andalas and Suci, the only two Sumatran rhinos ever to be born in captivity.