When 45-year-old Sudan died this week in Kenya, the world lost a rhino but not a species. It’s true that Sudan was the last male white northern rhino on Earth — two females remain. But the northern white is a subspecies, not a full species, and it had already been functionally extinct for at least a decade.

The rest of the rhino species, however, if given safe havens and adequate numbers of breeding individuals, can rebound. Unlike the northern white rhino, the southern white rhino — another subspecies and Sudan’s close kin — is a conservation success story: in the early 1900s, there were fewer than 200 animals; today there are more than 20,000, primarily in South Africa.

Why are the stories of these two closely related rhino populations so different?

An enormous amount of effort and resources were expended in trying to conserve the northern white rhino. In 1995, the International Rhino Foundation began investing several million dollars in protecting the subspecies. But after more than a decade of intensive engagement in Garamba National Park in Congo, with repeated incursions from the Janjaweed militia — and later the Lord’s Resistance Army — as well as large-scale poaching of rhinos and elephants, eight animals in captivity were all that remained. Each one was geriatric or had reproductive health issues or both. In 2008, the world’s best rhino trackers were unable to confirm the existence of any wild rhinos in Garamba.

Some have suggested that the northern white rhino might be recovered using advanced reproductive technologies: for example, in vitro fertilisation or nuclear transfer (cloning) theoretically could be used to produce embryos for placement in surrogates from the southern white rhino population. Scientists at the Smithsonian Conservation Biology Institute have experience using comparatively simple artificial insemination to help to recover the rare black-footed ferret and giant panda. But those successes depended on many years of research with readily available animals. With so little knowledge about the details of rhino reproductive physiology, and the complexities of converting cells in the laboratory into viable embryos, both IVF and cloning — neither of which has been useful in conserving any wildlife species — are long-shot options.

Instead, it makes more sense to shift attention to other rhinos. Poaching networks have been destroying African rhinos at the rate of nearly three animals a day. Still, many brave, dedicated people risk their lives and families protecting the remaining 20,000 wild southern white rhinos, the 5,000 black rhinos in southern and eastern Africa and the 3,500 greater one-horned rhinos in India and Nepal, as well as the 67 Javan and fewer than 80 Sumatran rhinos in Indonesia. Sumatran rhinos are continuing to decrease despite protection, and rhino experts agree that their best chance of survival now may be in breeding centres.

That is the difference between the demise of the northern white rhino and the remaining rhino species and subspecies. These other rhinos can still be saved, although time is running out, with effective protection of wild populations, improved support in the countries where the animals live and a growing agreement on the need for back-up or “insurance” populations through scientifically managed breeding programmes.

Sudan’s sad story has ended. The story of successful rhinoceros conservation is still being written.

•David Wildt is a senior scientist at the Smithsonian Conservation Biology Institute who leads its Centre for Species Survival. Susie Ellis is executive director of the International Rhino Foundation