Northern square-lipped rhinoceros
The northern white rhinoceros (Ceratotherium simum cottoni ), or northern square-lipped rhinoceros, is one of two subspecies of the white rhinoceros (the other being the southern white rhinoceros). Formerly found in several countries in East and Central Africa south of the Sahara, this subspecies is a grazer in grasslands and savanna woodlands. Since 19 March 2018, there are only two known rhinos of this subspecies left, called Najin and Fatu, both of which are female; barring the existence of unknown or misclassified male northern white rhinos elsewhere in Africa, this makes the subspecies functionally extinct. The two female rhinos belong to the Dvůr Králové Zoo in the Czech Republic but live in the Ol Pejeta Conservancy in Kenya and are protected round-the-clock by armed guards.
According to the latest International Union for Conservation of Nature (IUCN) assessment from 2020, the subspecies is considered "Critically Endangered (Possibly Extinct in the Wild)."
At the end of 2015, scientists from the Leibniz Institute for Zoo and Wildlife Research, San Diego Zoo Global, Tiergarten Schönbrunn, and Dvůr Králové Zoo developed a plan to reproduce northern white rhinos using natural gametes of the living rhinos and induced pluripotent stem cells. Subsequently, in the future, it might be possible to specifically mature the cells into specific cells such as neurons and muscle cells, in a similar way in which Katsuhiko Hayashi has grown mouse oocytes out of simple skin cells. The DNA of a dozen northern white rhinos has been preserved in genetic banks in Berlin and San Diego.
In August 2019, ten egg cells (five from Najin and five from Fatu) were harvested to be artificially inseminated with the frozen sperm of a northern white rhino as part of a project by the Leibniz Institute for Zoo and Wildlife Research, Dvůr Králové Zoo, Kenya Wildlife Service, and Avantea. In September 2019, scientists announced that they fertilized in vitro the eggs with frozen sperm taken from dead males; two of the resulting embryos were viable. In January 2020, it was announced that "another embryo" was created using the same techniques; all three embryos are "from Fatu", until they can be placed into a surrogate mother, probably a southern white rhino. In December 2020, 14 egg cells were retrieved from Fatu; eight of them were fertilised by the sperm of the dead northern white rhino Suni, resulting in two viable embryos. No egg cells were retrieved from Najin. As of February 2022, there are a total of fourteen northern white rhino embryos created, 11 from eggs from Fatu inseminated by sperm from Suni and 3 inseminated by sperm from Angalifu.
The northern white rhino formerly ranged over parts of northwestern Uganda, southern South Sudan, the eastern part of Central African Republic, and northeastern Democratic Republic of the Congo. Their range possibly extended as far west as Lake Chad, into Chad and Cameroon.
Poachers reduced their population from 500 to 15 in the 1970s and 1980s. From the early 1990s through mid-2003, the population recovered to more than 32 animals. Since mid-2003, poaching has intensified and further reduced the wild population.
*estimate
