One Life: Rhinos

22 September 2021

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Rhinoceroses, more commonly known as rhinos, are the second largest land mammal on earth. At the beginning of the 20th century, 500,000 roamed Africa and Asia, but today very few survive outside national parks and reserves due to persistent poaching and habitat loss. 

The different species of rhinos

There are five living species of rhinos in the world; white, black, Indian, Javan and Sumatran. There are two subspecies of white rhinos; the northern and the southern white rhino, and four subspecies of black rhino; western, eastern, south-western, and south-central rhino. 

Like to wallow in the mud

During the heat of the day, these magnificent mammals can be found sleeping in the shade or wallowing in muddy pools to cool off. Mud protects their skin from the strong sun (it’s a natural sunblock) and wards off biting bugs. When it’s hot, rhinos will wallow in mud for many hours.

Can be solitary or social 

For the most part rhinos are solitary animals and avoid each other. Some species, particularly the white rhino, sometimes live in small groups known as a ‘crash’. Crashes are usually made up of a female and her calves, although adult females can be seen together too. 

Males like to be left alone, unless in search of a female to breed with. They are very territorial and mark out their area of land with their poo. In fact, rhinos often use piles of poop to communicate with each other, since each rhino’s dung smells unique.

Rhinos have their own bodyguards

Rhinos are often seen with red-billed birds called oxpeckers (or “tick birds”) perched on their backs. Oxpeckers live off the parasitic insects that live in a rhino’s thick skin. This is a mutually beneficial relationship as the oxpeckers get food and the rhinos get pest control and are alerted to danger.  

In Swahili, oxpeckers are called “Askari wa kifaru”, meaning “the rhino's guard”. Rhinos have poor eyesight so if a human is approaching, oxpeckers give off a loud cry which alerts the rhino of the potential danger. 

In tracking wild black rhinos, researchers found that those carrying oxpeckers avoided more humans than rhinos who were alone. Oxpeckers can detect humans at 61 metres on average four times further than a rhino   and the more oxpeckers the rhino carried, the greater the distance at which a human was detected. 

The researchers suggested that 40-50% of all possible black rhino-human encounters are prevented by oxpeckers, a considerable advantage against being poached. 

Despite this closely tied relationship, oxpecker populations have significantly declined. As a result, most wild black rhino populations now live without oxpeckers nearby. But based on the findings in this study, reintroducing the bird back into rhino populations may bolster conservation efforts.

Can tell a lot from a call

The more social rhino species, the southern and northern white rhinos, use a call called a contact call pant to communicate to one another. It can be heard over long-distances and researchers have found that they say a lot about the caller...

In one study, scientists played calls from different individual rhinos to a group of ten wild southern white rhinos. They included calls made by both familiar and unfamiliar southern white rhinos, both males and females, and calls from northern white rhinos. They then monitored the behaviour of the rhinos to see how they responded. 

They found that the rhinos responded differently depending on who the caller was. The rhinos could tell whether the caller was familiar or unfamiliar to them, whether they were male or a female, and whether they were a fellow southern white rhino or a northern white rhino. 

The researchers also analysed the calls and found that they differed in structure depending on whether they were performed by a male or female rhino. The male rhinos responded more strongly to female calls than to other males. 

In another study, researchers found that each call could be linked to an individual, in the same way that our voices are unique to us

Rhinos have very poor eyesight, and so being able to communicate vocally with one another over long distances is crucial. This research is important because it helps us to understand more about them. Understanding how they communicate with one another may also be critical for improving conservation efforts. 

Rhinos really are amazing animals.

Rhino conservation

The Javan and Sumatran rhinos in Asia are critically endangered. There are thought to be less than 80 Sumatran rhinos in the wild. A subspecies of the Javan rhino was declared extinct in Vietnam in 2011. A small population of around 60 Javan rhinos still clings to survival on the Indonesian island of Java. 

Successful conservation efforts have helped the third Asian species, the greater one-horned (or Indian) rhino, to increase in number. Their status was changed from Endangered to Vulnerable, and they survive in northern India and southern Nepal. They number around 3,500but the species is still threatened due to poaching for their horns.

In Africa, southern white rhinos, once thought to be extinct, are another conservation success as they have been brought back to sustainable numbers. In fact, there are thought to be just under 19,000 in the wild. Like the Asian rhinos however, they too are being increasingly poached for their horns, and their numbers are now crashing. 

Black rhinos have doubled in number over the past two decades from their low point of fewer than 2,500 individuals, and there are now thought to be around 5,000 in the wild. This is still a fraction of the estimated 100,000 that existed in the early part of the 20th century.

The western black rhino and northern white rhinos have recently gone extinct in the wild.

The main threat to these beautiful animals is illegal hunting, largely because their horns are used in traditional medicine, particularly in Asia.

To save the remaining rhinos, countries must work together to protect conservation sites and, crucially, to stop the illegal trade in rhino horns. That means stopping the poachers who kill the rhinos, but it also means tackling a vast network of organised crime that ships the horns to Asia.

It is also important to end the demand. Rhino horns are status symbols in China, and so people pay a lot of money for them. If demand could be stopped, some of the rhino species could start to recover. It may well be too late for some of the species and subspecies whose populations are now so small they could never recover, but it is not too late for them all. 

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