White rhinos can grow to weigh more than 5,000 pounds, which is almost as much as a Land Rover rolling along on the Serengeti. The Sumatran rhino is the smallest of its kind, with the largest individuals barely reaching a ton in weight. A large male hippopotamus can actually exceed the largest rhino in size – perhaps by as much as half a ton – but because it spends most of its time in rivers and lakes, biologists consider it an aquatic, not a land mammal.
Rhinos have poor eyesight, but very well-developed senses of olfaction (smell) and hearing.
This might explain why a rhino will charge when startled. Perhaps you’ve heard the old joke: “How do you stop a charging rhino? Take away his credit card!” All kidding aside, it’s said that a rhino has difficulty detecting someone standing only a hundred feet away if the individual remains still. However, if the person makes the faintest sound or the wind is blowing toward the rhino, it will easily detect him, even at much greater distances. The olfactory portion is the largest area of the rhino’s brain.
African rhinos have a symbiotic relationship with oxpeckers, also called “tick birds”.
In Swahili, the oxpecker is called “askari wa kifaru”, which means “the rhino’s guard”. The oxpecker eats ticks and other insects that it finds on the rhino, and creates a commotion when it senses danger. This helps alert the rhino. Indian or greater one-horned rhinos have similar symbiotic relationships with other bird species, including the well known myna.
Most rhinos use piles of dung to leave “messages” for other rhinos.
Nuances in the smell of dung can tell a rhino a lot about others in the area. Each rhino’s smell is unique and identifies its owner. The dung of a young rhino smells different than that of an adult. A male’s dung smells different than a female’s, and the dung of a female estrus gives off a different odor than that of a non-reproductive female. Combined with urine left along trails, dung piles create invisible “borders” around a rhino’s territory.
Rhinos have existed on earth for more than 50 million years.
The first rhino ancestors appeared on Earth during an epoch known as the Eocene, along with a number of other mammal species. Earth’s climate at the start of the Eocene was very warm, with temperatures at the poles and the equator not being significantly different, and little or no ice to be found. By the end of the epoch, however, ice sheets and glaciers had returned.
As odd as it may seem, the earliest rhinos lacked horns. Several extinct species once roamed throughout North America and Europe, but today rhinos are found only in Africa and Asia. No rhino species have ever inhabited the South American or Australian continents.Historic photo courtesy Bateleur Safaris, remaining photos © Gretchen Healey