August 12, 2019

Late last month, on Sunday, July 28, a southern white rhinoceros calf was born at the San Diego Zoo Safari Park in southern California. The baby rhino, named Edward, marks the first instance of a successful artificial insemination (pregnancy induced by other than natural means) birth of a southern white rhino in North America. Artificial insemination of southern white rhinos, which were once endangered, has rarely been successful. Just two other southern white rhinos have been born this way prior to Edward’s joyful appearance. But baby Edward may soon have company. A second artificially inseminated southern white rhino is due to give birth at the safari park later this year.

One-day old Edward shelters beneath his mother, Victoria, at the Nikita Kahn Rhino Rescue Center at the San Diego Zoo Safari Park on July 29, 2019. Credit: © San Diego Zoo

Edward’s mother, Victoria, was artificially inseminated on March 22, 2018, following hormone-induced ovulation. White rhino gestation (the period of pregnancy) is normally around 485 days—but Victoria carried her calf for 493 days. That’s more than 16 months! The San Diego Zoo Safari Park, a center for the preservation and display of endangered species, has naturally bred southern white rhinos before. But the artificial insemination and Edward’s successful birth represented an important step in increasing white rhino as well as other rhinoceros populations that are critically endangered—particularly the northern white rhino, a subspecies of the southern white rhino.

Only two northern white rhinos remain on Earth, and both are female and beyond breeding age. The last male died in March 2018. Scientists have access to frozen reproductive material of the northern white rhino, however, and they hope to use artificial insemination or in vitro fertilization (IVF) to allow a southern white rhino to act as a surrogate mother. In IVF, an embryo is created in a laboratory and then transferred to a surrogate mother. Scientists hope to achieve a northern white rhino birth within the next 10 years. Without some form of assisted reproduction, the animals will soon be extinct.

Southern white rhinos, too, once stood on the brink of extinction. In the early 1900′s, overhunting and habitat loss had reduced Africa’s southern white rhino population to fewer than 50 animals. Protections and conservation measures allowed the population to rebound, however, and today thousands of animals live both in the wild and in parks and zoos around the world.

The white rhino is the largest of all rhinoceroses. It stands about 5 to 6 feet (1.5 to 1.8 meters) tall. In some cases, it may be over 6 feet (1.8 meters) tall and 15 feet (4.6 meters) long. It weighs up to 4 tons (3.6 metric tons). The animals face grave threats from habitat loss and poachers, who illegally kill rhinoceroses and sell their horns and skin. In some Asian traditions, the powdered horn of the rhinoceros is believed to have healing qualities. Rhinoceros skin, blood, and urine are also sometimes used in traditional medicine.

December 5, 2016

Imagine going to the zoo and seeing a horselike rhinoceros the size of a small house. It may sound like a fairy tale monster, but Paraceratherium—break it down: para-cera-therium (par uh sehr uh THIHR ee uhm)—was real and it was the largest land mammal that has ever lived. Paraceratherium, which provided inspiration for the gargantuan AT-AT walkers seen in the Star Wars film and entertainment franchise, reached over 16 feet (5 meters) in height. Its skull alone was over 4 feet (1.2 meters) long.

Watch their step: a Paraceratherium herd feeds on a not-so-small leafy tree. Credit: American Museum of Natural History

A prehistoric relative of the modern rhinoceros, Paraceratherium roamed central Asia between 20 and 30 million years ago. It was about 10 feet (3 meters) taller than modern rhinos, and it had no horn. The giant walker had long legs and a long neck to reach leaves in the treetops. Paraceratherium ate vast amounts of plant matter every day to maintain its massive 15-ton (13.6-metric ton) weight. It was so big that even a newborn calf was too much for many large predators to handle, especially with its massive mother lurking protectively nearby. Males had very thick skulls, which they used on each other as clobbering weapons while competing for mating rights with females. The thunderous stomping and skull-crashing during these combats probably warned other creatures to stay far away.

Scientists suspect that Paraceratherium’s cumbersome size led to its demise. Such a gigantic body requires a lot of food fuel and can easily overheat, which is why most modern mammals tend to be small- to medium-sized. Droughts, food shortages, and heat waves would have left Paraceratherium quite vulnerable. Females gave birth to only one calf every few years, so it would have been difficult for these prehistoric giants to keep their population numbers up during tough times.

October 20, 2014

The number of northern white rhinoceroses remaining on Earth has fallen to just six with the death of Suni, a 34-year-old male that lived at the Ol Pejeta Conservancy in Kenya. Even worse, Suni was one of only two breeding males. The first northern white rhino born in captivity, Suni was found dead in his boma (fenced corral) on Friday. Officials at the reserve said Suni was not a victim of poaching for his horn and ordered a necropsy. The other breeding male as well as two females still live at Ol Pejeta. Another southern white rhino is housed at the Dvur Kralove Zoo in the Czech Republic; two of the rhinos live at the San Diego Zoo Safari Park. No northern white rhinos are known to live in the wild now.

The northern white rhino is one of two subspecies of white rhino, the largest of all rhinoceroses. The other subspecies is the southern white rhino. The white rhino stands about 5 feet 8 inches (1.7 meters) tall. In some cases, it may be over 6 feet (1.8 meters) tall and 15 feet (4.6 meters) long. It weighs about 31/2 tons (3.2 metric tons).

The white rhinoceros is the largest kind of rhinoceros. There are two subspecies of white rhinoceros, the northern white rhino and the southern white rhino. (Clem Haagner, Bruce Coleman Inc.)

Suni, who was born at the Dvur Kralove Zoo, and three other rhinos were moved to the Ol Pejeta Conservancy in 2009 as part of a program called “Last Chance to Survive.” Officials had hoped that the natural conditions in Kenya would improve the rhinos’ chances of breeding and so save the subspecies from extinction. Suni had mated twice with one of the females, but the two did not produce offspring.

Thousands of northern white rhinos once roamed parts of East and Central Africa south of the Sahara. The animal’s situation grew dire in the 1970′s and 1980′s, as poaching for rhino horn cut the wild population, from about 500 to only 15. Many Asian people believe the powdered horn of the rhinoceros has healing qualities and can be used to cure lung and chest illnesses. Some people believe the horn has magical powers. Asian people also use the skin, blood, and urine of rhinoceroses to cure illnesses. Rhino horn now sells for more than gold or platinum. In a statement on Suni’s death, Ol Pejeta officials said, “the species now stands at the brink of complete extinction, a sorry testament to the greed of the human race.”

Additional World Book articles:

• Endangered species
• International Union for the Conservation of Nature and Natural Resources