Ancient Giants, Seldom Spotted
Rhinoceroses, or rhinos, are big and ancient-looking and can be dangerous. They can also be shy and are seldom seen. Once there were hundreds of rhino species, but today there are only five. One ancient rhino called Indricotherium (in-drick-oh-THAIR-ee-um] was the largest land mammal that ever lived. It was 5m high at the shoulders and 8.5m long — twice the size of today’s biggest elephant! Rhinos living now are still big, averaging 2-3m long and weighing up to3,600kg. But they have more to fear from people than we do from them.
The female white rhino is grazing alone in the photo above but white rhinos usually live in small herds.©G.Ellis/GLOBIO.org
Species: The Five Alive
The five rhino species left in the world are different in shape and size but they have one thing in common, they are all endangered.Chart courtesy of International Rhino Foundation 2007
To see the five species of living rhinos you would need to do a bit of exploring. First you would visit Africa for a look at the white rhino and the black rhino. Then you head to India and Nepal for a look at the Indian rhino. Last you would travel to the islands of Indonesia to see the Sumatran and Javan rhinos. These are the smallest and rarest rhinos in the world. All rhinos look heavy and strong, with nose horns and thick tough skin, like armor, covering their bodies. Rhinos belong to the same mammal family as horses, zebras and tapirs. All rhinos areendangered.
Habitats Ranging from Rainforests to Grasslands
Rhinos live in many different habitats. White rhinos and black rhinos live in Africa’s dry savanna woodlands and grasslands. The Indian rhino lives in the tall, high grasslands near rivers, where you must ride an elephant to find one. The smallest rhinos are found in the tropical rainforests on the islands of Sumatra, Java and Borneo. These two species are very rare and extremely difficult to find. Only a few photographs of them in the wild have been taken.
White rhinos are similar to cattle because they live in small herds and graze on grass in the African savanna.©G.Ellis/GLOBIO.org
White rhinos live in small groups, like cattle, and seem to be happy in many different types of habitats as long as there are grasses to graze. Each of the other rhino species is highly adapted to its habitat and can be found only there. For this reason, habitat destruction has caused rhino populations to decline.
How Does Rhino Loss Impact Other Species?
As rhinos disappear from their habitat, their loss causes many changes to the landscape. Like people, rhinos impact many other species with their actions. For example, black rhinos in Africa onlybrowse on tips of shrubs and small trees. As they eat, they arepruning the plant and limiting its growth. Many other species benefit from this pruning. As rhinos disappear, so do many of the other animals sharing their habitat. Bushes and trees take over the land and force species like antelope to leave in search of food. Eventually the whole habitat has changed. For some species this change can mean death or worse, extinction of the whole species.
Rhinos are herbivores meaning that they only eat plants like trees, grass and bushes.©G.Ellis/GLOBIO.org
The First Rhinos: Small and Furry
The first mammals we call rhinos appeared about 60 million years ago. Many of these early rhinos were small. They looked more like today’s horses and large furry pigs. Fossils, discovered bypaleontologists, tell us the earliest rhinos lived in North America. Over the next few million years they spread across Asia and into Africa. Some had thick hair. Others were striped. One, the Big Horn Rhino, had a tremendously long horn over 2.5 meters! Only Australia, New Zealand, South America, and Antarctica have never had rhinos. The last rhinos to live in North America died out approximately five million years ago.
Mating Can Be Dangerous
Female rhinos are old enough to have babies when they are about four to six years old. Males mature around seven years. Choosing a mate can be difficult and dangerous. Male rhinos sometimes fight over the females. Because of their sharp, dagger-like horns, these fights can result in nasty wounds.
Choosing a mate is a dangerous and complicated process. Male rhinos compete for female attention by fighting each other.©G.Ellis/GLOBIO.org
Once the male and female rhino have chosen one another, mating may last for several hours. Afterwards the male leaves. A female’sgestation period lasts 15-16 months. Normally only one baby, or calf, is born. On very rare occasions there may be two.
That’s a BIG Baby!
Wobbly at first, an hour after it is born a calf can stand steadily. Newborn rhinos are pretty big. Indian and white rhino calves are the biggest. They’re about 0.6m long and weigh45kg or more. For the first year, the calf only feeds on its mother’s milk. Even on a calf a few weeks old, a small horny bump appears on the end of its nose. It looks like a knob by the time the baby is about five weeks old.
For the first year, rhino babies stay very close to their mothers for protection and care.©G.Ellis/GLOBIO.org
A newborn calf is at risk from hyenas and large cats like tigers and lions. A calf stays near its mother for protection for about four to five years, or until its mother getspregnant again. Sometimes a calf is as large as its mother before leaving her side. White rhino calves are the exception. They stay with their mothers and the small herds. Rhinos can live a long time, about 50 years. Adult rhinos have no natural predators because they’re so big. Humans are their only predator.
Aggressive Attackers, or Simply Scared?
Most rhinos are gentle and timid. They have a bad reputation for being very aggressive, but that may be partly because they get frightened easily. Also, they have poor eyesight. They rely on their strong sense of smell to tell them a stranger is approaching. But if the wind is blowing the wrong way, they may not know someone is there until it’s too late.
If a person or animal comes too close or threatens a mother and calf, the mother threatens the intruder by snorting loudly. If that does not scare the person or animal away, the mother may charge. If a rhino attacks, it can do so with great speed. Despite being heavy animals with a bulky body, rhinos are remarkably fast! The two types of African rhinos can reach a speed of 56 kph while charging an enemy. That’s as fast as a galloping horse! The other three species—Indian, Sumatran and Javan rhinos—use their speed to disappear to safety in the thick grass or jungle.
So What Does a Rhino Do All Day?
Most rhinos live alone. Only the African white rhino lives in small herds. Rhino territory is well marked with trails bordered with urine and piles of dung. Indian rhinos have special glands in their forefeet that leave scent trails while they walk in the forest. Rhinos are active in the morning and evening, but seek shade in the hot sun.
Rhinos use urine to create invisible boundary lines, much like state borders, to outline their territory.©G.Ellis/GLOBIO.org
All rhinos are herbivores, feeding on grasses and the twigs, branches, shoots and leaves of bushes and trees. The white rhino and Indian rhino are grazers. Like cows, they spend their day head down, munching away on grasses. The other three species are browsers. They have specially designed upper lips that work like a tiny elephant’s trunk to twist around twigs and leaves, stripping them into their mouths.
The Poop on Rhinos
The plants rhinos eat don’t always contain many nutrients, so rhinos spend most of each day wandering about their habitat eating as they go. Eating all the time also makes them poop a lot. The poop is pretty dry, and if you pick it apart you can often see some of the things the rhino has been eating. These piles of poop often contain seeds that will eventually germinate and grow. By pruning bushes and small trees and dispersing seeds in their poop, rhinos have a very important role in maintaining the health of the habitat they live in.
Rhino poop contains many seeds from the bushes and small trees they eat, which later grow into new plants that grow in the rhino’s habitat.©G.Ellis/GLOBIO.org
Endangered Now, Extinct Soon?
This rhino had its horn removed to protect it from illegal poachers who kill rhinos simply for their horns.©G.Ellis/GLOBIO.org
All rhinos are endangered and very close to extinction. They are in trouble due to the loss of their habitat to deforestation and agriculture. They are also in trouble due to other human activity. People hunt rhinos illegally, which is calledpoaching. They also kill rhinos for their horns. Why? Some Asian cultures believe the rhino’s horn has magical powers for use in traditional medicine, but science has not found any evidence that this is true. The horn also has a value to certain cultures living in Northern Africa and the Arabian Peninsula of the Middle East where the long curved handles of special knives are made from a single horn. It is illegal in all countries to sell or trade rhino horn.
Even though rhinos are endangered, there is hope they will survive. Both African species, with the help of humans and international laws against poaching, are increasing in number. And in India and Nepal the Indian rhino is slowly repopulating many of the tropical Teraigrasslands where it was once so common.
Big Animal, Big Challenge for Scientists to Study
To study the behavior of animals so large and potentially dangerous can be difficult. Too close and you could get killed. Too far away and you can’t learn anything. So what to do? Technology can help.
First, the rhino can be carefully shot with a small dart containing a sleeping drug. A few minutes later, after the rhino falls asleep, scientists can move in and attach a small radio transmitter. The transmitter will send back information about the rhino’s movements after it wakes up. Using computers and GPS signals, scientists can track a rhino in thick bush, over hilly country and even at night. Over time, the rhino’s travels will build a map telling scientists where it wanders in the habitat—its territory.
How Do You Move a Sleeping Giant? Quietly, and with 30 Friends
People are also helping rhinos return to some of the habitats they disappeared from. When rhino populations in one park or reserve grow large enough, a few individual rhinos, males and females, can be moved, or translocated. The rhinos are darted to sleep and then a team of 20-30 people move in and load the sleeping giant onto a truck. The process is dangerous for rhinos and for the people moving them.
Zoos are also helping us understand more about rhinos. For the rarest rhinos, the Sumatran and Javan rhinos, their survival may depend on how well we learn to breed them in captivity while we work to protect their wild tropical rainforest home from destruction.