for National Geographic News
The Czech zoo where the rhinos came from, Dvůr Králové, is the only zoo in the world to have bred northern white rhinoceroses in captivity, the last time in 2000.
The only other two northern white rhinoceroses in captivity, which live at the San Diego Zoo, have not reproduced.
Scientists behind the relocation operation, dubbed Last Chance to Survive, hope conditions in Kenya will spur the two males and two females to mate more frequently.
"We successfully bred five generations of black rhino, but the white rhinos breed seldomly and nobody knows why," said Dvůr Králové director Dana Holeckova, who traveled to Kenya for the rhinos' arrival.
"I am sure that zoologists will find the key to solve this problem, but for the northern white, we [at Dvůr Králové] have no time. In 25 years we produced five babies, but it is not enough."
Three of the five rhinos born at the zoo are among the animals brought to Kenya, while the other two remain in the Czech Republic.
Rhinos on a Plane
The Czech zoo's four northern white rhinoceroses were packed into wood-and-metal crates amid freezing temperatures on Saturday.
The animals arrived in balmy Kenya early Sunday morning after an eight-hour flight on a cargo jet.
From the Nairobi airport, the rhinos were trucked 180 miles (290 kilometers) up to Ol Pejeta Conservancy, where handlers had built special wooden enclosures.
The rhinos will later be released into a much larger fenced area and placed under 24-hour guard.
The northern white rhinoceros historically ranged over what is now southern Sudan, the Democratic Republic of Congo, Uganda, and Chad.
Like rhinoceros species across Africa, the northern white rhinos have been decimated by poaching and have not been spotted in the wild since 2005.
Rhinos are poached primarily for their horns, which are used to make dagger handles or are ground into powders for use in traditional medicines.
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