The subspecies needed to reproduce.
The Last-Ditch Journey Back to Africa
By the 2000s, conservationists faced an increasingly desperate situation.
Only a handful of northern white rhinos remained in captivity, and breeding attempts had produced limited results.
Scientists and conservation organizations developed an ambitious plan.
In December 2009, four northern white rhinos were transported from Dvůr Králové Zoo to Ol Pejeta Conservancy in Kenya.
The four were Sudan, another male named Suni, and two females, Najin and Fatu.
Najin was Sudan's daughter.
Fatu was Najin's daughter and therefore Sudan's granddaughter.
The hope was simple but uncertain: perhaps returning the animals to a more natural African environment—with more space, natural vegetation and a different climate—might encourage successful breeding.
Ami Vitale documented the transfer.
She first encountered Sudan in the Czech Republic while he was being prepared for the journey. She later recalled seeing him surrounded by snow before he was flown thousands of miles south to Kenya.
The move was extraordinary.
Four members of one of the rarest large mammals on Earth were being transported across continents because traditional conservation options were running out.
Vitale later described the project as a desperate attempt to save an entire subspecies.
At Ol Pejeta, the rhinos lived under extraordinary protection.
Armed guards watched over them around the clock.
The security was not symbolic.
Even animals this rare remained potential targets for poachers seeking their horns.
Sudan eventually became one of the most famous animals in the world.
In 2017, conservationists even created a profile for him on the dating app Tinder as part of an awareness and fundraising campaign.
He was jokingly described as the world's most eligible bachelor.
Behind the humor was a grim reality.
There was almost no time left.
Why Natural Breeding Failed
The relocation to Kenya did not produce the hoped-for calves.
Sudan and the other rhinos did mate, but pregnancy never followed.
Veterinary examinations eventually revealed why.
Both Najin and Fatu had reproductive conditions that made natural pregnancy impossible.
BioRescue, the international scientific consortium now leading reproductive efforts, says the two females were diagnosed with severe reproductive pathologies.
Their ovaries could still produce viable egg cells, but neither female could safely carry a pregnancy.
Meanwhile, the population continued shrinking.
Suni, the other male at Ol Pejeta, died in 2014.
Nabire, another northern white rhino living in the Czech Republic, died in 2015.
Later that year, Nola, a female living at the San Diego Zoo Safari Park, died.
That left just three northern white rhinos alive worldwide:
Sudan.
Najin.
Fatu.
By then Sudan was elderly, and his reproductive capacity had declined dramatically.
There would be no natural recovery.
When Sudan died in 2018, the situation became even clearer.
The world had two northern white rhinos left.
Both were female.
The Two Survivors
Najin was born in 1989.
Fatu was born in 2000.
They remain at Ol Pejeta Conservancy in Kenya today.
They are not simply endangered animals.
They are the only two living northern white rhinos known to exist anywhere on Earth.
That reality produces an unusual conservation dilemma.
Biologically, the northern white rhino is often described as functionally extinct because the surviving animals cannot reproduce naturally.
But the subspecies is not yet completely gone.
Living cells remain.