A Detailed Review of Rhinoceros’ Nutritional Habits: What are Rhinos and What Do They Eat?

The rhino is one animal that humans have greatly wronged over the centuries. From the destruction of their natural habitat to the tragic poaching they experience, rhinos hardly have any reason to appreciate our species. These majestic beasts, having a global population of more than half a million just a century ago, now have very few members and are on the verge of extinction.

Scholars and rhino lovers can agree that these large mammals have highly fascinating characteristics apart from the attractiveness of their meat and horns to poachers. This comprehensive guide focuses on one intriguing aspect of rhinos — their nutritional habits. It also touches on other amazing facts about rhinos.

Notably, this piece aims to familiarize you with the natural diet of several rhinoceros species and how certain human activities affect their food availability. But before we delve into these intricate details, let’s look at some intriguing facts about these monstrous mammals.

Exciting Facts About the Rhinoceros — What Are Rhinos?

Rhinoceros [Greek (rhis/rhin — nose; keras — horn)] refers to several giant horned mammals belonging to the family Rhinocerotidae. They’re native to Africa and Asia and are the second-largest extant land animals, after elephants.

On their nose, rhinos possess one or two horns, made up of keratin, a fibrous protein found in hair, and thus are not actual horns. Rhinos were among the most successful lineages of hoofed mammals historically, but their total population in recent times may be fewer than 30,000.

Their size ranges from a length of 2.5 meters (8 feet) and a shoulder height of 1.5 meters (5 feet) in Sumatran rhinoceroses to a length of 4 meters (13 feet) and a shoulder height of almost 2 meters (7 feet) in the larger white rhinoceroses.

An adult rhino can weigh 3–4 tons in some species. In modern species, their feet feature three short toes with broad, blunt nails at the end. Rhinos belong to the order Perissodactyla, including the equines, and are more closely related to tapirs, horses, and zebras than elephants.

Rhinos have significantly thick skin, forming plate-like folds, particularly at their shoulders and thighs. Apart from the Sumatran rhinoceros, they’re nearly or entirely hairless.

All rhinoceros species are gray or brown, regardless of their name. However, white rhinoceroses are relatively paler than the others.

Generally, rhinos are solitary creatures. Individuals typically stay away from each other. One exception is the white rhinoceros, living in groups of up to 10 members. In solitary species, the rhinos divide their home territory with well-worn tracks and often mark the borders with urine and dung piles.

Fun Fact — Alpha male Indian rhinos can spray urine over a distance of 16 feet. Female Sumatran rhinos have also been seen spraying urine 69 times in 12 hours before giving birth and even after weaning the calf. While male rhinos mark their territories by spray urinating, females mask their calf’s scent with urine. Meanwhile, did you know that a rhino’s fart smells like sulfur?

Rhinos have poor eyesight, which they compensate for with their sharp senses of hearing and smell. Like elephants, they communicate with infrasonic frequencies below the human hearing threshold. They may use this unique adaptation to keep in touch with each other when they occupy dense forests. Female rhinos may also communicate with infrasonic frequencies to attract males when they’re ready to breed.

Although most rhinos prefer to avoid humans, males and females with calves may attack with minor provocation. Black rhinoceroses (Diceros bicornis), which are typically ill-tempered and unpredictable, may charge upon perceiving any unfamiliar sound or smell.

Despite their size, rhinos are extraordinarily agile. Black rhinoceroses can reach a speed of about 45 kilometers per hour, even in thickets, and can reverse rapidly after missing an attack.

Rhinos have a symbiotic relationship with oxpeckers. Oxpeckers typically sit on a rhino’s back and feed on the bugs crawling on the rhino’s skin. As payment for the bug meal, the oxpeckers warn the rhino when danger approaches by making calling sounds.

When rhinos are pleased, they utter a loud “mmwonk” sound with their mouths.

Distribution and Species of Rhinoceros

About 5 rhinoceros species and 11 subspecies inhabit Africa and South Asia. Rhinos once occupied Europe, as seen in the now-extinct wooly rhinoceros (Coelodonta antiquitatis) that lived during the Pleistocene Epoch, surviving until the last glacial period.

According to Save the Rhino, 500,000 rhinos occupied Africa and Asia at the advent of the 21st century. However, the group estimates there are 29,000 rhinoceroses in the wild at present.

The five extant species of rhinoceros include:

• White rhinoceros: Southern white rhinoceros (Ceratotherium simum simum) and northern white rhinoceros (Ceratotherium simum cottoni)
• Sumatran rhinoceros (Dicerorhinus sumatrensis)
• Black rhinoceros (Diceros bicornis)
• Javan rhinoceros (Rhinoceros sondaicus)
• Greater one-horned rhinoceros or Indian rhinos (Rhinoceros unicornis)

Rhinoceros’ Habitats

White rhinoceroses and black rhinoceroses dwell in grasslands and floodplains in Africa’s eastern and southern regions. On the other hand, the greater one-horned rhinoceros (Indian rhinoceros) is found in the marshes and rainforests of northern India and southern Nepal. Sumatran rhinos and Javan rhinos are restricted to rainforests and swamps in Malaysia and Indonesia.

Although rhinos are solitary mammals, they sometimes form groups called crashes. A female and her calves form rhinoceros crashes. Meanwhile, dominant males rule over marked areas of land. A dominant male may permit sub-dominant males to reside on his territory.

Females typically wander freely around various territories, possibly facilitating contact with males, leading to mating.

Rhinos spend the majority of their time searching for food and only sleep during the most extreme temperatures. When these horned mammals aren’t feeding, they can be observed relishing a refreshing mud soak. Mud soaks also help protect rhinos from bugs and insects — the mud itself functions as a natural sunblock.

It’s worth noting that a rhinoceros’s diet depends on the species and the animal’s specific habitat.

General Nutrition of Rhinos

Rhinos are generally herbivores, feeding on various plant-based diets, including the following:

• Grasses
• Shrubs
• Trees
• Leaves
• Fruits
• Vegetables
• Roots
• Barks
• Twigs

Still, each of the five rhinoceros species has specific physiological and environmental differences. Two vital aspects of the nutrition of rhinos include diet diversity and the required food amount.

In terms of dietary habits, rhinoceroses fall into either of two categories, including:

• Grazers
• Browsers

Grazers comprise rhinos that keep their heads low and prefer shorter grasses when feeding. White and Indian rhinos are regarded as grazers.

On the other hand, browsers tend to focus on foods above their eye level. They prefer twigs, leaves, and fruits. This category includes black, Javan, and Sumatran rhinos.

Despite this diet variety, rhinos have a sweet tooth, implying that browsers may sometimes choose to graze and vice versa. Meanwhile, food availability can cause a shift in the preferred diet, with most rhinos resorting to consuming roots and barks during food scarcity. Roots also provide hydration for rhinos during droughts and dry seasons.

For better understanding, we’ll cite the distinct nutritional habits of the five species and species-specific facts.

1. Nutritional Habits of and Facts About White Rhinoceros (Ceratotherium simum)

The white rhino is among the two rhinoceros species native to Africa. Weighing up to 1,600 kilograms (3,500 pounds), it’s the largest extant rhinoceros and the second-largest land animal, after elephants.

White rhinos are 4 meters (13 feet) long and almost 2 meters (7 feet) high. They’re the only rhinoceros in which males are considerably larger than females.

The white rhino lives in groups of up to 10 members and fights with its horns. It’s paler than other rhinoceroses, hence its name.

Historically, the species was subdivided into two subspecies — southern white rhinoceros (ceratotherium simum simum) and northern white rhinoceros (ceratotherium simum cottoni). However, comparative anatomy and DNA analysis indicate that the two groups are distinct species.

White rhinoceroses are a grazing species possessing a broad square muzzle. The latter characteristic earned them the alternate name “square-lipped rhinoceros.” They prefer short grasses 7–10 centimeters (3–4 inches) high and are among the world’s largest pure grazers.

If water is available, white rhinos drink twice a day. However, they can survive without water for 4 or 5 days in dry conditions. They spend nearly half of the day feeding and one-third resting. Due to their impressive size, they need to consume up to 100 pounds of grass a day to retain their weight and nutrition.

They typically stay under the shade of large trees to shield themselves from intense sun rays. Like other species, they’re fond of wallowing in mud holes to significantly lower body heat. White rhinos are believed to have changed the structure and ecology of the savannah’s grasslands through their grazing habits and other activities.

The range of white rhinoceroses isn’t continuous. They were once widespread over a relatively vast bushveld area south of the Zambezi River. In South Africa, the southern white rhinoceros population was barely fewer than 100 individuals about 1900. However, there are over 19,000 south white rhinos at present.

Quick Fact — There are only two living northern white rhinoceroses globally, and both rhinos, mother and daughter named Najin and Fatu respectively, live in captivity in Kenya. The last-known male northern white rhino, Sudan, died in 2018.

2. Nutritional Habits of and Facts About Sumatran Rhinoceros (Dicerorhinus sumatrensis)

The Sumatran rhinoceros is a rare Asian species reputable as the most ancient of all extant rhinos. It’s the smallest living rhino, with males and females weighing less than 850 kilograms (1,870 pounds). While Sumatran rhinos are 2.5 meters (8 feet) long, they’re 1.5 meters (5 feet) high at the shoulder.

Historically, Sumatran rhinos occupied Assam, Myanmar, Thailand, Laos, Vietnam, Malaysia, Sumatra, and other regions of Asia. They’re only found among a few protected areas in Sumatra and the forests of Indonesia Borneo today.

Regarded as one of the species on the brink of extinction by the IUCN, the white rhino has lost more than 80% of its population since the 1930s. According to a survey, about 220–275 adult Sumatran rhinos remained worldwide in 2008. More recent statements from IUCN officials suggest that fewer than 30 adult Sumatran rhinos exist globally, out of less than 80 in total.

Fun Fact — Sumatran rhinoceroses are the most distinct extant species because they’re covered in long body hair. They inhabit forests, swampy areas, thickets, and bamboo forests. In mountainous regions, the Sumatran rhino is an active climber.

Sumatran rhinos are primarily browsers, feeding on pioneer plants that thrive in gaps in the forest created by fallen trees. They mainly eat in the morning and just before nightfall. A typical folivore, the Sumatran rhino diet comprises the following:

• Young saplings
• Leaves
• Twigs
• Shoots

The Sumatran rhino typically consumes up to 50 kilograms (110 pounds) of food per day. With a trunk diameter of 1–6 centimeters (0.5–2.5 inches), tree saplings constitute the most significant portion of a Sumatran rhino’s diet.

The rhinos push the saplings down with their bodies, passing over them without stepping on them to feed on the leaves. The majority of the plant species that form these rhinos’ diets only exist in small portions, indicating they frequently change their diets and feeding habits in various locations.

The Sumatran rhino consumes species from the following plant families:

• Euphorbiaceae
• Rubiaceae
• Melastomataceae

Eugenia is the most consumed plant species of the Sumatran rhinoceros. Meanwhile, the vegetarian diet of Sumatran rhinos is highly fibrous but moderate in protein. Additionally, salt licks are important mineral sources for Sumatran rhinos.

3. Nutritional Habits of and Facts About Black Rhinoceros (Diceros bicornis)

The black rhino, the third-largest rhinoceros, is native to Africa. Typically, it weighs between 700 and 1,300 kilograms (1,500–2,900 pounds), with no significant sex difference in size. Black rhinoceroses stand 1.5 meters (5 feet) high at the shoulder and are 3.5 meters (11.5 feet) long.

They occupy various habitats, including:

• Open plains
• Savannahs
• Thickets
• Sparse thorn scrub
• Dry forests
• Mountain forests
• Moorlands of high altitudes

The black rhinoceros was originally widespread in the Cape of Good Hope, southwestern Angola, East Africa, parts of Ethiopia and Sudan, and even parts of West Africa. However, uncontrolled poaching reduced their population from an estimated one million individuals to about 2,400 by 1995.

Black rhinos are selective herbivorous browsers, with grasses playing a minor role in their diet.

The typical diet of a black rhino includes the following:

• Leafy plants
• Branches
• Shoots
• Thorny wood bushes
• Fruits

They can survive without flowing water for some time if succulent plants, such as euphorbias, are abundant in their dry habitats. Still, they readily and regularly drink water where available. They also dig for water in arid habitats.

The black rhinoceros has been observed feeding on 220 plant species. Though diversity is essential to their diet, they also require many food sources to stay nourished.

Their feeding habits can reduce the number of woody plants, which may benefit grazers. They have a considerably exclusive diet, preferring several plant species and selecting leafy species in the dry season. Primarily attracted to woody plants in non-dry seasons, 18 known woody plant species constitute the diet of the black rhinoceros.

Black rhinos also tend to choose food based on quality over quantity, with the most population in areas with better food quality. In terms of its chewing adaptations, the black rhinoceros has a two-phased chewing activity, a cutting ectoloph, and more grinding lophs on the lingual side.

Quick Fact — Black rhinos usually fight each other, frequently resulting in fatalities. They have the highest deadly combat rates recorded for mammals, with about 50% of males and 30% of females dying from combat-related injuries.

4. Nutritional Habits of and Facts About Javan Rhinoceros (Rhinoceros sondaicus)

The Javan rhinoceros is the world’s rarest rhino species and one of the most endangered mammals globally, with no more than 68–74 surviving members. It’s only found on the Javan Island in Indonesia. Though only a few species have been scaled and measured, they weigh 900–2,300 kilograms (2,000–5,100 pounds) and are 2–3.2 meters (6–11 feet) long, making them about the same size as black rhinos.

Javan rhinoceroses occupy forests, swampy areas, regions of thick bush, and bamboo bushes. Like Sumatran rhinos, they’re active climbers in mountainous areas.

Fun Fact — One distinct feature found in male and female Javan rhinos is their modified lower incisors, similar tusks, which they employ when fighting. Male Javan rhinos also possess short horns of 25 centimeters (10 inches).

Javan rhinoceroses are predominantly herbivorous browsers, consuming pioneer plants that dominate forest clearings produced by fallen trees. They’re fond of eating the shoots, young foliage, twigs, and fallen fruit of plants. Chiefly, they favor plants growing in sunny areas, shrubs, and other vegetation without large trees.

Javan rhinos bring down saplings to access their food and grab them with their prehensile upper lip. They’re the most adaptable feeders of all existing rhinoceros species, requiring an estimated 50 kilograms (110 pounds) of food per day.

Like Sumatran rhinos, they need salt in their diet. They obtain salt from drinking seawater, as salt licks aren’t readily available in their habitat.

5. Nutritional Habits of and Facts About Greater One-Horned Rhinoceros (Rhinoceros unicornis)

The greater one-horned rhinoceros is the largest Asian rhino, and it’s native to the Indian subcontinent, thus it’s also known as the Indian rhinoceros. More or less the same size as the white rhino, it weighs between 1,800 and 2,700 kilograms (4,000–6,000 pounds).

Indian rhinos stand 2 meters (7 feet) high at the shoulder and are 3.5 meters (11.5 feet). They inhabit the world’s tallest grasslands.

Unlike other rhinos that fight with their tusks, male greater one-horned rhinoceroses possess razor-sharp lower outer incisors used to inflict lethal wounds on other males when competing for breeding females.

Other characteristic features of Indian rhinos include:

• Large horn
• Skin tubercles
• Skin folds

Greater one-horned rhinos are principally grazers, like white rhinos. However, during the winter, they turn to browse for food.

Fun Fact — Greater one-horned rhinos’ dung piles support the growth of about 25 plant species whose seeds are ingested by the rhinos and germinate in their nutrient-rich excrements.

Nutrition of Young Rhinoceros

Female rhinos carry their fetus for about 15–16 months before giving birth to a single baby rhino, known as a calf. Rhino calves are breastfed with milk by their mothers for the first 18 months of their life. Afterward, they start consuming plant-based diets.

Challenges Associated With Feeding Rhinos in Captivity

Several times, the diet offered to captive rhinoceroses is a poor replica of the actual food consumed by rhinos in the wild. This disparity can lead to various health issues in captive rhinos.

Browsers, such as black rhinoceroses, consume numerous plant species in the wild, which provides them with adequate nutrients. However, most managed care institutions can’t offer sufficient browse quantities to captive rhinos, leading to limited access to essential minerals.

The black rhinos diet in captivity may comprise the following:

• Pelleted feed
• Alfalfa hay
• Grass-legume mixes

Alfalfa hay contains high protein, calcium, and iron levels and may cause diarrhea and colic issues. Browsing species in captivity may also develop iron overload disorder (IOD) when they’re overly fed with alfalfa and other legumes. Similarly, a pelleted feed may contain high starch and soluble sugar levels, prompting obesity and metabolic syndrome.

Since obesity is a well-recognized risk rhinos under human care face, constant monitoring of body weight and condition is recommended for all rhinoceros species.

Predators of Rhinos

Adult rhinos typically lack natural predators due to their impressive size, dangerous horns, tusks, and strength. However, vulnerable young calves may fall prey to tigers and hyenas. The most dangerous animals to adult rhinos are humans, who hunt them for their horns and meat.

How Human Activities Negatively Affects Rhinoceroses’ Population

For years, human activities have been the leading cause of the diminishing number of rhinos. Some human activities directly affect the rhino population, while others have indirect but adverse effects. The following sections explore the various mechanisms by which humans influence rhinoceroses’ population.

1. Agriculture

Humans continuously transform grasslands and forests to arable lands for agricultural purposes. This shift robs rhinos of their natural habitats and deprives them of food sources.

2. Civilization

The rapid growth of the human population is proportional to the reduction in the rhino population. As humans expand their territories and colonize more parts of the planet, they carry out unfavorable activities against rhinoceroses.

Deforestation, bush burning, clearing of grasslands and woodlands for the construction of roads and houses, pollution, and carbon emission are ways that human civilization has affected the rhino population adversely. Namely, these activities eliminate the natural habitats and food sources of rhinoceroses.

3. Poaching

Rhino poaching is perhaps the most apparent human activity that has led to the endangerment of several rhino species. In many parts of the world, rhinoceroses have been hunted towards extinction.

They’re mainly slaughtered for their meat, horns, and skin. Some poachers use rhino horns for ornamental purposes, while others sell the horns to traditional medical practitioners. The latter is particularly widespread in China, where rhino horns are a prized ingredient in traditional medicine.

Rhino poaching causes significant damage to the rhino population because the poaching rate dramatically exceeds the rhinos’ birth rate. Widespread around the world historically, several rhinoceros species have been driven to extinction, while others are endangered and likely to become extinct in the future. Due to the damage rhino poaching has caused and is still causing, the barbaric practice has been declared illegal and punishable in most regions of the world.

Though the rate of rhino poaching has reduced significantly, several criminals still illegally slaughter rhinos. In South Africa, 769 rhinos were killed in 2018, 594 were slaughtered in 2019, and 394 were poached for their horns in 2020.

FAQ

Do rhinos eat meat?

No, rhinos are pure herbivores that solely consume plant-based diets. They lack the proper apparatus for the digestion of meat.

What do white rhinos eat?

White rhinos are large grazers that forage on short grasses on the ground.

Do rhinos eat pancakes?

Rhinos don’t eat pancakes because they don’t recognize them as food. Instead, they feed on grasses and plant parts.

What do Javan rhinos eat?

Javan rhinos are herbivorous browsers that primarily feed on young foliage, twigs, plant shoots, and fallen fruits.

What do rhinos eat in the wild?

Wild rhinos are herbivores divided into two groups — grazers and browsers. Grazers feed on short grasses, while browsers prefer foods above their eye levels.

Do albino rhinos eat humans?

No, albino rhinos don’t eat humans. All rhino species are plant-eaters, regardless of color or appearance.

What did wooly rhinos eat?

Now extinct, wooly rhinoceroses (Coelodonta antiquitatis) fed on grasses and sedges that grew in the mammoth steeper. They also foraged on small plants, mosses, and lichens.

Do rhinos eat humans?

No, rhinos don’t eat humans; they aren’t carnivores. So, even when they attack humans, they aren’t motivated by human meat.

Conclusion

Rhinoceroses are typically herbivores, feeding on grasses, trees, vegetables, barks, etc. However, particular diets may vary with species and feeding habits.

These elegant mammals are better off alive than dead. Their presence on earth benefits the ecosystem as their fecal matters facilitate plant growth. Consequently, rhino poaching should be substantially discouraged through policies, education, and law enforcement. Rhino-hostile human activities, such as deforestation and bush clearing, should also be deterred or curtailed to tolerable levels.

Finally, the diet offered to captive rhinos must be of optimal quality and nutritional value to prevent obesity and other diet-related disorders in the animals.