First published October 22, 2021.
In October 2021, the scientists trying to save the northern white rhino announced that Najin, then 32 and one of only two members of the subspecies left alive, would no longer donate egg cells to the rescue programme. The decision followed an ethical risk assessment that weighed her age and signs of ill health against the value of further procedures. Her daughter Fatu, born in 2000, became the only egg donor. Both animals are female, and no male has survived since 2018, so every hope for the subspecies now rests on assisted reproduction.
What was decided in October 2021
The announcement came from BioRescue, an international consortium led by Germany's Leibniz Institute for Zoo and Wildlife Research, working with Safari Park Dvůr Králové in the Czech Republic, the Italian laboratory Avantea, Kenya's Ol Pejeta Conservancy, the Kenya Wildlife Service, the Wildlife Research and Training Institute and other partners.
Since 2019, vets had been collecting immature egg cells from both rhinos under general anaesthesia. Each procedure carries some risk, and for an older animal those risks grow. After reviewing Najin's condition, the team concluded that continuing would not be in her interest. In the team's own statement, it had "reached the decision to retire the older of the two remaining females, 32-year-old Najin, as a donor of egg cells."
Najin was not removed from the conservancy or from care. She continued to live at Ol Pejeta with Fatu, under round-the-clock protection.
Najin and Fatu: the last two
Najin was born in 1989 at Dvůr Králové Zoo, the daughter of Nasima and Sudan. Fatu was born at the same zoo on 29 June 2000. In December 2009 the two were flown to Ol Pejeta in Kenya, along with the males Sudan and Suni, in the hope that a more natural setting would encourage breeding.
No calves followed. Suni died in 2014, and Sudan, the last known male, was put to sleep in March 2018 after a long-running leg infection. Neither remaining female is thought able to carry a pregnancy to term, so any future calf will have to be carried by a surrogate.
The pair are guarded day and night by armed rangers, and their keepers have become well known in their own right as the people who look after the last of a lineage.
How the subspecies was pushed to the brink
The northern white rhino once ranged across parts of northwestern Uganda, southern South Sudan, the eastern Central African Republic and northeastern Democratic Republic of the Congo. Poaching for horn, fuelled by demand in traditional medicine and ornamental carving, cut numbers from around 500 to about 15 during the 1970s and 1980s.
A small population in Garamba National Park, in the DR Congo, briefly recovered to more than 30 animals by 2003. Then poaching surged again amid regional conflict. A 2005 survey found only four, none were seen after 2006, and the subspecies is now listed by the IUCN as Critically Endangered and possibly extinct in the wild.
The closely related southern white rhino tells a more hopeful story. Reduced to a tiny remnant in South Africa around 1900, it was rebuilt through protection into the most numerous rhino in the world, although it too faces heavy poaching pressure today. That recovery is part of why scientists believe a well-managed population can bounce back from very small numbers.
The BioRescue plan: eggs, embryos and surrogates
With only two females left, natural breeding is impossible. BioRescue's plan works in three stages:
- Collect eggs. Immature egg cells are harvested from the living females and matured in the laboratory.
- Create embryos. The eggs are fertilised with frozen sperm stored from northern white bulls that have since died, then grown into early embryos and frozen in liquid nitrogen.
- Transfer to surrogates. Embryos are placed into southern white rhino females, which are close enough relatives to carry a northern white calf.
Alongside this, researchers in Germany and Japan are working on turning stored skin cells into stem cells and eventually into egg and sperm cells. If that succeeds, it could add genetic diversity from animals that died long ago.
At the time of Najin's retirement, Kenyan scientists said the work with Fatu was going well. David Ndeereh of the Wildlife Research and Training Institute told Reuters there were 12 pure northern white rhino embryos and added: "We are very optimistic that the project will succeed." The team's stated hope then was a first calf within about three years and a growing population over the following two decades.
Why animal welfare shaped the decision
Retiring a donor when only two remain might look like giving up a precious resource. In practice, it shows how modern conservation tries to balance the survival of a species with the wellbeing of the individual animals involved.
BioRescue works with ethicists from the University of Padua, who assess each step of the programme for its risks and benefits to the animals. Repeated anaesthesia and egg collection are demanding procedures. For an ageing rhino with health concerns, the team judged that the extra eggs were not worth the risk to her. Najin's earlier eggs and the embryos already made remain part of the project.
The decision also highlights a broader point: a high-tech rescue cannot replace the habitat protection and anti-poaching work that would have kept the subspecies alive in the first place.
Where the programme stands now
The years since 2021 have brought progress and setbacks. In 2023 the team achieved the first rhino pregnancy from IVF, using a southern white rhino embryo in a southern white surrogate named Curra. Curra died in November 2023 of a rare bacterial infection, but the pregnancy showed that embryo transfer in rhinos can work.
Fatu has continued to donate. By August 2025, BioRescue reported 21 egg collections from her since 2019 and a total of 38 pure northern white rhino embryos, stored in Germany and Italy. Transfers of those embryos into southern white surrogates in July 2024, December 2024 and May 2025 had not yet produced a lasting pregnancy. The team reported that Fatu's ovarian health appeared to have improved over the course of the procedures.
No northern white rhino calf has been born so far, and the original three-year target has passed. Still, the embryos are banked, the methods are improving, and the goal remains to return the northern white rhino one day to its former range.
Sources: Wikipedia: Northern white rhinoceros; idw / BioRescue, 25 August 2025: northern white rhino rescue update; BioRescue project website; Reuters, 21 October 2021: original reporting and David Ndeereh quote.
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