North­ern white rhino female Nabiré, one of the last five north­ern white rhi­nos in the world, died on Mon­day, July 27 in Dvůr Králové Zoo, Czech Repub­lic. She deceased due to a large patho­log­i­cal cyst that rup­tured inside her body.

“It is a ter­ri­ble loss. Nabiré was the kind­est rhino ever bred in our zoo. It is not just that we were very fond of her. Her death is a sym­bol of the cat­a­strophic decline of rhi­nos due to a sense­less human greed. Her species is on the very brink of extinc­tion,” said Pře­mysl Rabas, the direc­tor of the zoo.

Nabiré was born on Novem­ber 15, 1983 at the Dvůr Králové Zoo as one of the only four north­ern white rhi­nos ever bred in cap­tiv­ity. She spent all her life in Dvůr Králové. “The patho­log­i­cal cyst inside the body of Nabiré was huge. There was no way to treat it,” said Jiří Hrubý, a rhino cura­tor of the zoo.

Thanks to 40 years of breed­ing efforts, the Dvůr Králové Zoo pro­longed the very pres­ence of NWR on this planet. The ini­tial group was brought to Dvůr Králové Zoo in 1975 from south­ern parts of Sudan. The group con­sisted of two males and four females. Of this group two indi­vid­u­als — a male and a female — are still alive. Female Nola lives at San Diego Zoo, while male Sudan was translo­cated in 2009 to the Ol Pejeta Wildlife Con­ser­vancy in Kenya together with male Suni and females Nájin and Fatu. The lat­ter two were born at the zoo in Dvůr Králové.

Nabiré was one of the ani­mals that par­tic­i­pated in Dvůr Králové Zoo efforts to breed these rarest rhi­nos in the world. How­ever, Nabiré could not con­ceive nat­u­rally due to a large amount of cysts in her uterus.

Nev­er­the­less, her left ovary appeared to be healthy, so it was hoped she might become a donor of eggs for in vitro fer­til­iza­tion and arti­fi­cially cre­ate an embryo. For this rea­son, the poten­tially healthy ovary was imme­di­ately after her death removed and taken to a spe­cial­ized lab­o­ra­tory in Italy. Tis­sue sam­ples that could be used for sci­en­tific research and repro­duc­tion work were col­lected as well.

A breed­ing programme

Dvůr Králové Zoo with its part­ners con­tin­ues with the efforts towards sur­vival of the north­ern white rhino.

Apart from its own breed­ing pro­gramme, Dvůr Králové Zoo shifted part of a NWR group to the San Diego Zoo in 1989 to reduce the risk of pos­si­ble dec­i­ma­tion of the only cap­tive ani­mals held at a sin­gle loca­tion due to unex­pected health problems.

Unfor­tu­nately, the females did not con­ceive in San Diego and Dvůr Králové Zoo remained the only facil­ity where north­ern white rhi­nos man­aged to repro­duce. But even in Dvůr Králové the rate of repro­duc­tion was too low. In addi­tion to research of hor­monal cycles, which has taken place in Dvůr since the 1980s, the zoo began to coop­er­ate with the Leib­niz Insti­tute for Zoo and Wildlife Research (IZW) in Berlin on arti­fi­cial tech­niques of repro­duc­tion in 2001.

All females were stim­u­lated with hor­monal implants and females Nájin and Fatu were repeat­edly arti­fi­cially insem­i­nated with semen of north­ern males in 2006 and 2007.

After unsuc­cess­ful attempts with arti­fi­cial insem­i­na­tion, the zoo decided to go for a next step — in Decem­ber 2009, the zoo trans­ported two males and two females to Ol Pejeta Con­ser­vancy in Kenya. It was hoped that nat­ural sur­round­ings close to their orig­i­nal habi­tat could give them an impulse that would prompt their breed­ing. Although the acclima­ti­za­tion of the ani­mals went well, the hor­monal cycles of the females improved and repeated mat­ing was observed, unfor­tu­nately, no preg­nancy occurred.

Thus, the team from IZW Berlin with sup­port from the Dvůr Králové Zoo and other part­ners cur­rently aims at devel­op­ing a robust pro­to­col to opti­mize a pro­ce­dure of har­vest­ing and matur­ing oocytes, fer­til­iza­tion of oocytes fol­lowed by embryo trans­fer with south­ern white rhi­nos. When the process is stan­dard­ized on these close — but mor­pho­log­i­cally and genet­i­cally dis­tinct¹ — rel­a­tives of north­ern white rhi­nos, the team will aim at har­vest­ing oocytes from the last north­ern white rhino females, mature oocytes, fer­til­ize them with north­ern white rhino semen, gen­er­ate embryos on a large scale and cryo-​preserve them or trans­fer them directly into a sur­ro­gate mother of a south­ern white rhino origin.

Accord­ing to health exam­i­na­tion that took place at the end of 2014, the two females in Ol Pejeta Con­ser­vancy, Nájin and Fatu, could become donors of eggs for the exper­i­ment. Also, Dvůr Králové Zoo col­lab­o­rates with the San Diego Zoo Global and other part­ners on this chal­leng­ing task to save the north­ern white rhino by using advanced cel­lu­lar technologies.

¹ North­ern white rhi­noc­eros, a dis­tinct species!

(Source: Dvůr Králové Zoo news release, 28.07.2015)