Pursuing another strategy, scientists at San Diego Zoo in California last year showed that banked tissue from the almost extinct northern white rhino (Ceratotherium simum cottoni) could be induced to form a line of pluripotent stem cells, capable of forming many tissues. It's possible that these cells could be used to generate working gametes, using the same techniques that have produced sperm in mice.
Hildebrandt advocates natural mating before attempting IVF or other reproductive technologies, but he is already starting to bank rhino tissue. With part of a €500,000 (US$640,000) grant from the German Federal Ministry of Education and Research awarded in December 2010, he established a cryo-bank facility in Kota Kinabalu. In it are fibroblasts from Tam and Gelogob, a blind and elderly female rhino in captivity at the Tabin Wildlife Reserve. Cells from Puntung will join them shortly. “If we can't find the solutions, then people after us can,” Hildebrandt says. “We have the responsibility to make it available to the next generation.”
Yet the chance that such technologies will succeed in a species like the Sumatran rhino, whose basic biology is still poorly understood, seems remote. Roth says that tissue banking “is not a priority compared with some of the other issues we're up against”. And the Indonesian government's action plan for rhino conservation, spanning 2007–17, contains no mention of tissue banking.
Money, too, is in short supply. It is a stinging irony that by far the biggest donor to BORA is the Sime Darby Foundation, the philanthropic arm of the Sime Darby Group, based in Kuala Lumpur, one of the world's biggest producers of palm oil, the crop that led to the destruction of much of the rhino's rainforest home. It has committed a further $2 million to fund BORA's operations up to 2015 and after that the charity is on its own. “This is a bit of a worry,” admits Payne. Hildebrandt says that his grant from the German government has expired. He knows that he needs some demonstrable success with Puntung to get more. “If we are not successful in the next few months, then I think the programme is over,” he says.
Other conservation biologists argue that it already is. Even if assisted reproductive technologies do prove possible, Fraser asks how long the new animals would survive. “My concern is that [the Sumatran rhino's] future viability as a species on this planet and the future viability of any offspring is really in question because the habitat just isn't there. So I question the priority setting, although I can certainly understand the emotional state of those invested in saving the animal.
Puntung, of course, is oblivious to the emotions and the debate. The operation over, Göritz injects her again to reverse the effect of the anaesthesia and within minutes she is out of the sling. Zahari enters the enclosure and unfurls a hose to spray her down. It's a ritual she clearly enjoys, raising her neck to meet the droplets of water as they rain down.
Puntung can savour a few weeks of rest and bananas, before science's next assault on her infertility.