The greater one-horned rhinoceros, or Indian rhino (Rhinoceros unicornis), is a massive herbivore native to the floodplains and grasslands of northern India and southern Nepal. It is the second-largest rhino species globally and the largest in Asia, with adult males often weighing over two metric tons. As a megaherbivore, the Indian rhino spends a significant portion of its day consuming various plant materials. Its diet is primarily driven by the availability of vegetation in its native, often swampy, environment.
The Primary Diet
The Indian rhinoceros is classified as a mixed feeder, but its diet is overwhelmingly dominated by grasses, making it primarily a grazer. Tall, reedy grasses constitute 80% or more of its total annual food intake in the wild. Specific species like Narenga porphyrocoma, Phragmites karka, and Saccharum spontaneum are frequently consumed due to their abundance in alluvial grasslands.
The rhino supplements its diet with a variety of other plant sources. These secondary items include aquatic plants, which are readily available in the marshy areas and water bodies it freque nts. The animal also consumes leaves, twigs, shrubs, and occasional seasonal fruits or flowers to ensure a balanced intake of nutrients and fiber. The species has been recorded to eat over 180 different plant species throughout the year, demonstrating high dietary flexibility.
Feeding Mechanics and Behavior
The Indian rhino possesses a specialized physical adaptation that facilitates its feeding style: a semi-prehensile upper lip. This muscular, pointed lip allows the rhino to grasp and manipulate the tall, coarse grasses and reeds that make up the bulk of its diet. It uses this lip to hook onto a clump of grass, bend the stem downwards, and then cleanly bite off the top section. This mechanism differs from the square lips of the grazing White Rhino and the highly prehensile lip of the browsing Black Rhino.
These massive herbivores consume a considerable volume of vegetation daily, estimated to be around 1% of their body weight. Feeding activity is concentrated during the cooler hours of the day, typically occurring in the early morning, late afternoon, and throughout the night.
During the heat of the day, rhinos often rest or wallow in mud and water to regulate their body temperature. Their digestive system is that of a hindgut fermenter, similar to a horse, which allows them to efficiently process the large quantities of fibrous plant material they consume.
Ecological Role and Habitat Influence
The composition of the Indian rhino’s diet is heavily influenced by seasonal changes and water availability in its floodplain habitat. During the dry season, when grasses become tough and less nutritious, the rhino increases its consumption of aquatic plants, leaves, and twigs to maintain its nutritional intake. Conversely, during the monsoon season, when grasslands are submerged, the rhino turns to taller-growing plants or those found on higher ground.
The species also engages in geophagy, the practice of consuming soil or mineral-rich earth, by visiting natural mineral licks. This behavior is important for a large herbivore to supplement its diet with necessary minerals and salts. By consuming and trampling vegetation, the Indian rhino acts as an ecosystem engineer, influencing the structure and composition of the grasslands.