It is a race against time to save northern white rhino from extinction

In the heart of Laikipia County, the clock is ticking for Najin and her daughter Fatu.

Every minute, these two northern white rhinos - the only ones left in the world - teeter on the brink of extinction.

Five years ago, Sudan, the last male, died of old age. A chance to reproduce naturally, for the two females left behind went with him. The cruel hand of nature would also strike, preventing Fatu, the youngest and most capable, from conceiving.

Now, scientists are racing against time while hoping that science will save the critically endangered species whose physical safety is guaranteed 24 hours a day by armed guards.

Oblivious to this fact, Najin and Fatu bask in the safety and comfort of their enclosure, grazing, supplementing their diet with fresh vegetables, hydrating their bodies and hiding from the hot sun. The pair, born and raised in captivity, spend their days under the care of Tawu, a wild and aggressive southern white rhino whose job is to teach the two how to graze, socialise and waddle in the mud.

"In 2009, the two were brought to Kenya together with Sudan and Suni, the only surviving males. The four had been living at Dvur Kralove Zoo in the Czech Republic, where all attempts to breed them had hit a wall. Ol Pejeta Conservancy's climate raised hopes that the four could breed naturally in the wild. It was not to be," says Zacharia Mutai, head caregiver of the two rhinos.

"We mated Fatu with Suni, hoping she would get pregnant, but it was unsuccessful. We would later realise that she has a deformity in her uterus that cannot allow her to carry a pregnancy. Worse still, we lost the males. Now, the only way to save them is through science. We collected semen from Sudan and Suni, and we have other semen collected in San Diego and the Czech Republic. We have also collected ova from Najin and Fatu that will be used to generate embryos," says Mutai.

Dr Stephen Ngulu, a veterinary surgeon and wildlife vet, says that the conservancy has brought together a consortium of reproduction experts to save the northern white rhino from exiting the face of the earth.

He said the team has been working since 2015 to optimise assisted reproduction techniques to propagate the northern white rhino species.

"Over the last five years, we have been collecting eggs using ultrasound-guided machines from the ovaries of the females. Before collecting those eggs, we inject the rhino with hormones to stimulate follicle production, which produces the eggs. We then collect the eggs and store them. For the last five years, we have conducted over 15 ova pickup procedures in the two northern white rhino females," explained Dr Ngulu.

"We have also been able to go further and do in-vitro fertilisation. This is an assisted reproductive technique that involves fusing a sperm from a male and an egg from a female to generate an embryo. We have produced 30 embryos, which we have preserved in liquid nitrogen. The next step would be taking and implanting the embryo," he adds.

He explains that due to Fatu's uterine malformation and Najin's old age, the embryos cannot be implanted in them. The next best option, he says, is to use a southern white rhino as a surrogate.

These females must be pure southern white rhinos of origin. Since northern and southern white rhinos are subspecies of the white rhino, they are very closely related in terms of body structure and size. As a result, the reproductive tract of a southern white can carry the pregnancy of a northern white rhino. In this case, the northern white rhino embryos are implanted into the surrogate female.

"Before you do that, you need to optimise the embryo implantation process in the rhino. This is not something that has been done before. Instead of implanting your pure northern white rhino embryo into a surrogate southern white rhino female and risk losing it, you first implant a southern white rhino embryo developed separately as a trial. Once the embryo is implanted and you confirm it is developing into a fetus, your technique has succeeded. You then bring the pure northern white rhino embryo and implant it into another surrogate to carry it to term," explains Dr Ngulu.

"This is what we achieved last year. We implanted a southern white embryo into a surrogate female for optimisation. This embryo was implanted successfully and started growing. Unfortunately, when we had El Nino rains towards the last quarter of 2023, the rains brought about bacterial infections. The female that was carrying this pregnancy got the infection and died. She was okay in the morning and died by noon. There was no time to detect the infection and treat her," said Dr Ngulu.

After the unexpected and devastating death, he and his team removed the fetus and performed DNA analysis to confirm whether it had developed from the implanted embryo. It was.

"That shows success in rhino IVF. It shows success in assisted reproduction in rhinos even though we had that setback," remarks Dr Ngulu.

The setback, however, fueled new hope, and they have set it upon themselves to prepare other surrogate females, who will then be implanted with pure northern white embryos.

Dr Ngulu says the process is usually done when the female is on heat and ovulating. Since the human eye cannot tell when this is happening, the vets have adopted a traditionally used livestock-keeping concept. It involves using a bull that has been vasectomised to tell when the females are on heat.

"We use a rhino bull to detect when the surrogates are coming on heat and ovulating. The bull will mount these females but cannot impregnate them. Once it mounts these females, we will know that they are ovulating. The assumption is that the bull has primed the female to get pregnant, and the uterus is ready for implantation. We then give ourselves between five and six days, bring the embryo, and implant it using ultrasound-guided techniques into one of the uterine horns," he says.

"After 40 to 60 days, you will come back, immobilise the rhino and check whether the embryo has implanted and is growing. If it doesn't implant, the cycle will happen again, and the bull will mount her because he has detected heat. These are procedures that are highly advanced and have to be learnt," he adds.

He explains that the team currently faces two setbacks—time and funding. Because the females are getting older, the quality of their eggs is diminishing, and their deaths are approaching. Besides, optimising the technique takes time, as it requires meetings, travelling, and seeking ethical approvals.

Ethical approvals, he says, involve assessments to analyse the effects of several immobilisations on the surrogate females. These have to be completed by veterinarians performing the procedure. The assessment also has to consider the vets' level of skill and whether they are able to perform the procedure safely with little to zero harm to the animal.

"The procedure has never been done in rhino. It is the first success story in Kenya, being done by Kenyans working with global partners. The effort to save northern white rhinos and devise techniques to save them involves a lot of funding. This includes funds to come up with equipment and drugs, to fly partners and collaborators in, to build infrastructure, to pay rhino keepers and others. There needs to be goodwill from supporters and the government from all over to support this noble cause so that it gets done. So that what we are doing can be used to save other species, not just the northern white rhinos," he says.

"In the meantime, we will continue to collect more eggs and create more embryos so that if we lose the females, we have enough embryos. We hope to do one embryo transfer in 2024."

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