The last surviving male white rhino Sudan holds the future of his species Reuters

With the last remaining northern white rhinos left in the world being either too sick or too old to breed, the rare species joins the list of animals made extinct because of humans. With little chance of rescuing the northern white rhinos through conventional methods, scientists are developing techniques "on the edge of available science" to save the critically endangered animal, the Times reported.

Experts from Germany, Italy, and the US are reaching the use of cloning, stem cells and in-vitro fertilisation (IVF) to keep the species alive. "It has huge echoes of Jurassic Park," said Richard Vigne, head of the Ol Pejeta conservancy in Kenya, where three out of the four remaining northern white rhinos live under 24-hour armed guard to protect them from poachers.

Just like in the 1993 film, where scientists cloned dinosaurs from fossilised DNA, experts hope to either clone the species or manufacture embryos from stem cells. Scientists have also explored using traditional IVF techniques, including harvesting eggs from the last remaining females, according to the Times.

With only three females left, however, "it is nearly impossible" to collect the eggs without damaging the animal, according to Thomas Hildebrandt, a wildlife fertility vet from Leibniz Institute for Zoo and Wildlife Research in Berlin.

"Human IVF has been developed over 30 years and it is still a challenge for the parents to achieve a baby," he said in the Times. "We are dealing with patients which weigh two tonnes and none of the protocols are fully established."

Once the vets are able to manufacture a viable embryo, it will be implanted into a surrogate mother from the northern white rhino's more abundant southern cousin.

"If we have the resources we will have the first northern white rhino calf in four years," Professor Hildebrandt added. But he warned that the lack of sufficient funding is slowing their progress, and a successful calf might take 15 years to be created, by then the last of the northern white rhinos will be dead.

The last male, Sudan, is 44-years old – rhinos have a maximum lifespan of between 40 to 50 years – and produces inferior quality sperm. The three females suffer from various ailments which prevent them from breeding.

The northern white rhino was common across the savannahs of central and eastern Africa, from Chad to Uganda, but the last wild sighting was in Garamba National Park, in the northeastern Democratic Republic of Congo, in 2006, according to the Times.

There have been unconfirmed sightings in South Sudan. But it is thought that all the wild animals have been poached for their horns.