White Rhinoceros

Ceratotherium simum

Class: Mammalia (Mammals)
Order: Perissodactyla
Family: Rhinocerotidae
Genus: Ceratotherium
Species: simum
Subspecies: C.s. simum (southern), C.s. cottoni (northern)

GREEN HEADLINE

Vanishing giants. The classic vision of an African savanna would be incomplete without rhinoceroses, colossal icons of their grassland homes. White rhinos Ceratotherium simum, in particular, are known for their formidable size. While large and tough-appearing, white rhino populations are fragile. Demand for their horns had led to rampant poaching and plummeting populations. Just two northern white rhinos C.s. cottoni remain in the world. Southern white rhinos C.s. simum are more abundant, but still in dire need of assistance if they are to have a secure future on our planet.

White rhinos are identified by the two horns on the end of their nose, with a larger front horn and a small inner horn. Rhino horns don’t have a bony core like other mammal horns. The outside is rather soft and can be worn down or sharpened after years of use. If a horn breaks off, it can gradually grow back. It is made of keratin, the same material that makes up our fingernails and hair.

Like other rhinos, white rhinos have a broad chest, thick skin, poor eyesight, and excellent hearing. Because rhinos are nearsighted, they often charge when startled. This defense mechanism has given them an undeserved reputation for having a bad temper. Their ears can move independently of each other, and one may be cocked forward while the other is directed backward, or both may perk straight up when an interesting sound that requires total concentration is detected.

Despite their name, white rhinos are gray in color. How the white rhino came to be called “white” is uncertain. One account says that it comes from the Dutch word wijde, or “wide,” referring to the white rhino’s wide lip or large size.

HABITAT AND DIET

Shrinking habitat. While once abundant throughout sub-Saharan Africa, white rhinos now live in small pockets of southern Africa, in long- and short-grass savanna and shrubland habitats. Only five countries are home to 99 percent of white rhinos: South Africa, Namibia, Botswana, Zimbabwe, and Mozambique. Of those, the vast majority are found in South Africa.

Chow down: White rhinos are herbivorous. Their broad, square lip is built for grazing. As they eat, they crop grasses so short that they create “grazing lawns” that benefit smaller plant-eating wildlife and serve as firebreaks. At the San Diego Zoo Safari Park, rhinos eat hay and high-fiber biscuits, along with carrots and apples.

FAMILY LIFE

Home turf: Dominant male rhinos occupy small territories. They only allow one or two subordinate males to share the territory. Neighboring dominant males respect one another’s space and rarely trespass, except to reach water during the dry season. Adult white rhino females are more social, often staying in groups of up to a dozen that include calves and subadults. A group of rhinos is known as a “crash.”

Females enter a dominant male’s territory when they are ready to mate. White rhino males can be persistent about courtship, pursuing females for 5 to 20 days. The male approaches females with a series of breathy “hic-pant” vocalizations, and may rest his chin on her rump to test whether she will tolerate mating. If successful, a calf is born 15 to 16 months later.

Big vocabulary. Like other rhinos, white rhinos make a variety of sounds to communicate with others. Long and short snorts are used to express anger or alarm. When startled, high-pitched screams indicate fear. A deep, resonant “mmwonk” means that they are content.

Smelly signals. Dominant male rhinos spend much of their time patrolling their territory and marking it with urine and dung, to communicate with neighboring rhinos. Subordinate males put little effort into such communication with scent, always deferring to the dominant male when they meet up.

AT THE ZOO

In 1971, 20 southern white rhinos arrived at the Safari Park to become the founding generation of the Park’s white rhino herd. Since then, more than 100 southern white rhinos have been born at the Safari Park.

San Diego Zoo Wildlife Alliance was one of the last organizations in the world to care for northern white rhinos. Nola, a 41-year-old female, passed away in 2015. As of 2021, the world’s only two remaining northern white rhinos live at Kenya’s Ol Pejeta Conservancy. San Diego Zoo Wildlife Alliance is leading efforts to save the northern white rhinoceroses at the Safari Park’s Nikita Kahn Rhino Rescue Center, through development of assisted reproductive technology, the use of biobanked genetic material, and work with southern white rhinos that may someday become surrogate mothers for a northern white rhino calf.

CONSERVATION

White rhinos’ large size protects them from savanna predators like lions and cheetahs. People pose the biggest threat to white rhinos’ survival. While rhinos have an excellent sense of smell, their poor eyesight makes them an easy target for poachers.

Hunted for horn: White rhinos once roamed widely across sub-Saharan Africa without much threat from other wildlife, thanks to their immense build. But the advent of high-powered weapons brought a new and deadly enemy: humans. Rhino horn—which is made of keratin, like human fingernails and hair—has been used as an unproven folk remedy to treat illnesses, and it has also been sold as a “status” item because of its rarity. Thousands of rhinos are slaughtered each year just for their horn, and their population has plummeted. To try to prevent this rampant poaching, many African countries have implemented measures to protect their rhinos. However, the increasing demand and high price paid for rhino horn encourages their continued slaughter and the international sale of their parts.

Hope for white rhinos: Currently, southern white rhino are listed as Near Threatened and northern white rhinos are listed as Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. With our conservation partners, San Diego Zoo Wildlife Alliance is contributing to efforts to secure a future for white rhinos. In Africa, we collaborate with our longtime partner, the International Rhino Foundation, to protect vulnerable populations in South Africa while also developing innovative methods to combat and reduce poaching. In the United States, conservation scientists from San Diego Zoo Wildlife Alliance’s Reproductive Sciences team are developing cutting-edge technologies that will allow northern white rhinos to be born through southern white rhino surrogate mothers. These methods include artificial insemination, in vitro fertilization, and embryo transfer. Meanwhile, San Diego Zoo Wildlife Alliance’s Conservation Genetics team is analyzing white rhino genome sequences to eventually generate embryos. We have hope that, one day, their work will result in healthy northern white rhino calves.

The Safari Park has one of the most successful conservation breeding programs for rhinoceroses under human care in the world. By August 2020, more than 100 southern white rhinos had been born at the Safari Park, representing hope for the future. San Diego Zoo Wildlife Alliance was one of the last organizations in the world to care for northern white rhinos. The last two remaining northern white rhinos live at Ol Pejeta Conservancy in Kenya as of 2021.

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