Which species only have 2 females?

How to save a species that only consists of two females

One thing is certain: if the northern white rhinoceros are ultimately rescued, it will go down in history as the species that was closer to the brink of extinction than any other. Only two specimens of this subspecies of the white rhinoceros have survived today - and unfortunately both are females.

Hope lives

And yet the hope of receiving it is not yet entirely illusory. In any case, artificial reproduction techniques must be used. Scientists from the Berlin Leibniz Institute for Zoo and Wildlife Research (IZW) have now reported an important stage win. They were able to take ten egg cells from the last two females living in Kenya. These are supposed to be artificially fertilized with the stored sperm of an already dead bull.

"The procedure is the result of years of research, development, adaptation and practice," said Thomas Hildebrandt from the Leibniz Institute and David Ndeereh from the Kenyan Wildlife Agency (KWS), who led the procedure in the Ol Pejeta wildlife reserve. "Both the method and the necessary equipment had to be developed from scratch." The egg cells will now be brought to Italy, where they will be artificially fertilized in a laboratory.

Inventory developments give you goose bumps

The procedure had previously been tried several times on animals of the related subspecies of the southern white rhinoceros, from which the northern part has been separated for a long time. There are around 20,000 specimens of this subspecies today - again, one has to say, because its population had shrunk to a full ten or was shot down at the end of the 19th century. That this near-extinction is even surpassed by the northern relatives a century later is a particularly tragic note.

And other rhinoceros also move in dangerous areas: it is estimated that there are still around 50 specimens of the Java rhinoceros, and a maximum of three times as many of the Sumatran rhinoceros. The Indian rhinoceros and the African black rhinos still have four-digit numbers.


Northern white rhinos once migrated through East and Central Africa in large numbers, but poachers wiped them out. They have been considered extinct in nature since 2008, and the few zoo specimens followed. Last year the last male in Ol Pejeta was euthanized because of old age. The news of Sudan's death went around the world.

But his daughter Najin and his granddaughter Fatu are now the last hope: According to researchers, they cannot carry offspring themselves due to various health problems, but their egg cells can be used for artificial insemination (IVF). Bull semen has been preserved in liquid nitrogen for some time. A southern white rhinoceros will then carry a young as a surrogate mother.

Even with a successful IVF baby rhinoceros, the preservation of the subspecies is not yet guaranteed. Since there are only two females and sperm fewer bulls, the genetic diversity would not be large enough to build a self-sustaining population. Therefore, parallel to artificial insemination, researchers at the Max Delbrück Center for Molecular Medicine are working on stem cell technology to breed sperm and egg cells from preserved rhinoceros body cells. (red, APA, August 24, 2019)