The northern and the southern white rhino look rather similar at first glance, but the two subspecies have very distinct features that are unmistakable at closer inspection. The northern subspecies has hairy ears, a slightly different skull and horn shape, a different shape of the neck and a different texture of the skin between the neck and the forelegs. Another important difference is the shape of the feet: the northern subspecies is more adapted to swamp habitat, while the southern is a typical savannah grazer – the shape of the feet reflects this adaptation. The two subspecies are also slightly different in weight and size.

Northern white rhinos are now widely believed to be extinct in the wild. The last four wild individuals were seen in Garamba National Park, DRC, in August 2005 and signs of their existence were still seen in 2007. There was an isolated and unconfirmed report of three white rhinos in southern Sudan in 2008, although surveys in June of that year failed to locate them. There are now just two rhinos left in captivity – Najin and Fatu – who live under close protection in a semi-wild environment on Ol Pejeta Conservancy in Kenya.

The main threat to their survival in the wild was (and still is for all rhinos) hunting — in particular for their horns, which are believed to have medicinal properties in some countries. Coupled with the heavy poaching threat was the outbreak of war in many parts of the northern white rhino’s home range, which quashed any protection and conservation initiatives.

The northern white rhino used to range over parts of north-western Uganda, southern Chad, South Sudan, the eastern part of Central African Republic and the north-eastern Democratic Republic of the Congo (DRC). There is fossil evidence that the northern white rhino ranged into the Rift Valley in Kenya 3,000 years ago.

White and black rhinos are actually both grey! The name ‘white’ comes from a misinterpretation of the Dutch word "wijde" (‘wide’ in English), which was actually used to describe the flat shape of the white rhino’s mouth. This is an adaptation helps them graze on grass, as opposed to the black rhino’s pointed mouth adapted for browsing on leaves, shoots and branches.

Four northern white rhinos – two males and two females – were transported to Ol Pejeta Conservancy from the Safari Park Dvůr Králové in the Czech Republic in December 2009. Scientists and conservationists hoped that a more natural habitat would encourage the animals to breed, as it became increasingly obvious that the numbers of captive northern white rhinos were dropping fast. One of the males, Suni, died in October 2014 of natural causes. The other male, Sudan died on March 19th, 2018 of old age. Females Najin and Fatu, who were born in the Safari Park Dvůr Králové, are now the only survivors of their subspecies.

Fatu was born on 29th June 2000, and her mother Najin was born on 11th July 1989. Sudan was Najin’s father (so Fatu’s grandfather). Suni and Fatu share the same father, a male named Saut.

In 2014 both Fatu and Najin were diagnosed with severe genital pathology, which prevented natural conception. This pathology was supposedly present for some time which is why either of the two did not became pregnant even though mating had been observed. Infertility and inability to become pregnant naturally is diagnosed frequently in female rhinoceros, which have not bred for longer periods of time. Despite uterine dysfunctions Fatu and Najin’s ovaries still carry viable oocytes. If some oocytes can be harvested, these can still be fertilised in the laboratory using frozen sperm form deceased males.

Natural reproduction is no longer an option after the death of the last male northern white rhino in 2018. But from several individuals, sperm has been collected and cryogenically frozen which now can be utilized for invitro fertilization (IVF). For that purpose, the harvesting of egg cells from the remaining two female individuals is necessary. Due to their inability to carry out a pregnancy for different health issues – and owing to the value of these two individuals to the species – transferring an embryo to Najin and Fatu is not an option. A surrogate mother from within the southern white rhino population needs to be found.
This approach may – if it is successful – yield several births of northern white rhino calves, but it has its limits. First the OPU procedure to collect eggs is a risky procedure and can only be conducted two or three times a year, so the number of natural gametes (and therefore possible attempts) is limited. And second the genetic variability is very limited too, because the number of individuals from which sperm and egg cells can be utilized is down to a handful. For this reason, the BioRescue consortium follows a second approach: the creation of artificial gametes via stem cell transformation. There is frozen tissue from a few more northern white rhinos available at the Cryobanks of Leibniz-IZW and San Diego Zoo bringing the gene pool up to 12 cell lines from 8 presumably unrelated founders adding to the semen of four bulls and the natural gametes from the two living females. Cells from skin tissue will be transformed into stem cells, which then can be developed into primordial germ cells and further into oocytes and sperm. This state-of-the-art approach is currently being developed by partners of the BioRescue consortium.

The long-term objective is to reintroduce northern white rhinos and future offspring into secure habitats within their former range. This objective may only be realised in 50-70 years. As none of remaining females is capable of natural breeding, we have developed assisted reproduction technologies that could produce a northern white rhino offspring.

After foundation of a viable breeding nucleus at Ol Pejeta, new populations can be translocated to create or reinforce existing white rhino populations with northern white rhino genes. By increasing the number of populations, the overall risk to the subspecies will be spread and reduced.

These northern white rhinos represent the last known individuals of the subspecies and so contain valuable and unique genes. Their genes evolved in the wild and give the northern white rhinos vital traits for survival in their natural habitat. For example, resistance to certain white rhino diseases in East Africa may only be provided by northern white rhino genes. Ultimately, the value of these animals can only be realised if they are reintroduced to the wild. Their genes can then be expressed in the environments in which they were evolved and so strengthen the white rhino’s chance of survival. The subspecies also plays an important role as a large herbivore in its native ecosystems.

Yes. The procedure has proven to be safe and reproducible. The first attempt was made in August 2019 and again in December 2019. Out of those two procedures, three pure northern white rhino embryos have been created. The embryos are now stored in liquid nitrogen.

Additionally, it is important to note that a second approach using stem cell technology is currently being developed to complement the efforts in the field of IVF using natural gametes. For further information see the question “So what options are left if the subspecies is to be saved?”

Artificial insemination is not an option for saving the NWR because neither Najin nor Fatu can carry a pregnancy. We therefore have to extract their eggs and fertilize them outside the womb. The team in Europe comprised of the Leibniz-IZW Berlin, Safari Park Dvůr Králové and Avantea Cremona is pioneering the IVF that has not been done with northern white rhinos before.

There are inbreeding issues with small number of founders, particularly if any of the animals are related. For this reason, the conservation strategy for the northern white rhinos in Ol Pejeta will include even utilization of genetic samples that are cryopreserved in special cryo-banks. For example, semen from at least four already dead northern white rhino males can be used for assisted techniques of reproduction. Also, the strategy may include inter-crossing NWR with southern white rhinos in order to maximise breeding opportunities and propagation of the northern gene pool. With careful conservation management, small rhino populations are able to reproduce at over 10% per annum and recover from very small to large healthy populations. This was achieved with the southern white rhino in South Africa, where numbers recovered from less than 50 animals to the current total of approximately 20,000 animals.

The quality of semen is good enough to produce a transferable embryo, the crucial part of IVF.

The team in Europe have collected ova from rhino females approximately 50 times with no health consequences for the females that underwent procedure. The success rate depends on quality of a donor (mainly related to age). There were post-reproductive females that showed no sign of follicles developed on their ovaries while with other females we were able to collect up to 11 oocytes during one collection. The protocol was tested on females of similar age like those in Ol Pejeta and the procedure went well.

Yes, the BioRescue-team in Europe has done repeated collections of ova. It is planned that even the NWR females will undergo repeated collections up to three times a year. By the way, one of the multiple donors in Europe naturally conceived after the collection procedure.

None so far.

The science has gone as far as creating a viable embryo and attempting the embryo transfer procedure. Seven attempts have been conducted in European zoos so far, but none have been fully successful yet. One of the transfers resulted in an extension of blastocyst (the embryo started to grow after the placement in uterus, but failed during the implantation). More embryo transfers are scheduled to be conducted in the coming months.

The animals belong to the Safari Park Dvůr Králové that coordinates efforts to save the northern white rhinos. While in Kenya, their wellbeing is overseen by a committee that comprises of representatives of Kenya Wildlife Service, Ol Pejeta Conservancy, Safari Park Dvůr Králové, Back to Africa, AfRSG and FFI.

The offspring born in Kenya will be housed on Ol Pejeta Conservancy in a 700-acre secure enclosure. They will belong to the Safari Park Dvůr Králové (every first calf) and to Kenya Wildlife Service (every second calf). It is planned that IVF will be performed even in European zoos.

We have not had a poaching on Ol Pejeta since 2017. We have 42 armed rangers that patrol the conservancy and 120 rhino patrol rangers. The northern white rhinos, surrogates and their offsprings will be under 24/7- armed surveillance. The enclosure they are housed in is right next to the armed rangers HQ

There are five southern white rhinos in the protected enclosure which have been kept empty for the purpose of this project. They will need to be anaesthetise as they are wild animals. They belong the Kenya Wildlife Service who is the custodian of wildlife in Kenya. For the embryo transfer, the animal has to be in full anaesthesia.