World Rhino Day: A Call to Action for a Prehistoric Giant’s Survival

Rhinoceros or rhino in short, is a symbolic species displaying the implications of the presently ongoing mass extinction, also known as the Holocene extinction driven by destructive and careless human activities. Rhinos, once a thriving population in the wild across many continents has now reduced to mere countable numbers and are restricted to conservation sites and to small isolated pockets. World Rhino Day commemorated on the 22^nd of September each year is a wake-up call for the plight of these horned grazers.

Distribution and IUCN status of different species of rhinos

The below mentioned summary of the five extant species of rhinos, their IUCN status, and their distribution, reveals the grim reality of the dwindling numbers of these animals.

1. Family Rhinocerotidae

Sub family Rhinocerotinae (Asian Rhinos)

Greater One-Horned Rhino (Rhinoceros unicornis)
- Common Name: Indian Rhino
- Distribution: Native to India and Nepal
- These species of rhinos are classified as vulnerable

Figure 2: the historic distribution of greater one horned rhino is shown by the region shaded in pink and their current habitat is shown by green patches along with their potential sites for reintroduction is shown by orange patches

2. Javan Rhino (Rhinoceros sondaicus)

Common Name: Javan Rhino
Distribution: Found only in Ujung Kulon National Park in Java, Indonesia.

The whole species of the Javan rhinoceros presently lives in a single national park, the Ujung Kulon National Park near the western tip of Java, after a second subspecies, which had been rediscovered in Vietnam only in 1988, was eliminated by hunters in 2010 (Brook et al., 2012)

3. Sumatran Rhino (Dicerorhinus sumatrensis)

Common Name: Sumatran Rhino
Distribution: Native to the islands of Sumatra and Borneo.

The population count of both the Sumatran and the Javan rhinoceros put together, have no more than 50–80 individuals living in isolated pockets of Indonesia. (Pusparini et al., 2015). This highlights the extent of the harm that has been caused to these species.

Sub family Dicerosinae (African Rhinos)

White Rhino (Ceratotherium simum)
- Common Name: White Rhino
- Distribution: Divided into two subspecies:
  - Southern White Rhino (Ceratotherium simum simum): Predominantly found in southern Africa, including South Africa, Kenya, Zimbabwe etc.
  - Critically Endangered Northern White Rhino (Ceratotherium simum cottoni): Almost extinct in the wild, with only a few individuals in captivity.

Tragically, this subspecies extinction is waiting to happen, as the last male northern white rhinoceros died in 2018, and the subspecies now consists of only two females. Although the subspecies of the north are critically endangered, with all that is known to remain to be two captive females, the southern white rhino has a population count equal to 20,405, making it the most abundant rhino subspecies in the world. This population count outnumbers all other rhino subspecies combined.

Figure 5: Population distribution of the White Rhino© International Rhino Foundation

The above maps of distribution of the Indian rhino and of white rhino shown by Figure 8 and 7 respectively, is alarming, and they highlight how severe is the impact of human activities on to the habitats and the distribution of these animals.

2. Black Rhino (Diceros bicornis)

Common Name: Black Rhino
Distribution: Found in eastern and southern Africa.
Classified as critically endangered

Morphology of Rhinoceros

Rhinos are often referred to as living tanks due to their distinct barrel-shaped torso; short, thick legs which gives it a sturdy and bulky appearance at a glance. To hold this amount of weight rhinos, have broad feet with three weight-bearing digits and their soles of the feet have a large pad to cushion the weight of the animal. The most striking feature of this animal is its single horn seen in Sub family Rhinocerotinae (Asian Rhinos) or a pair of horns seen in the Sub family Dicerosinae (African Rhinos), which unfortunately attracts negative attention from humans.

These horns are composed of tubular hairlike keratin filaments, which are outgrowths of the skin, and it is the same component that makes up human nails. Despite this, ignorance and false perceptions of reality have driven people to hunt rhinos for their horns, which are thought to have some medicinal value and also used as a status symbol.

The presence of thick skin, (which may reach up to 5cm in white rhinos), and skinfolds (which are more prominent in Asian and Indian species) give these animals an armoured appearance, thus these creatures are also referred to as armoured giants.

Figure 8 : highlights the variations in rhino based on the skin of rhinos, number of horns and the skin complexion

Unique feature and comparison of different rhino species

Although the name of the white rhino suggests white colour, in reality the rhino has no white complexion, instead the body color of a white rhino is actually more of a grayish or light slate. The colour of the rhino is also affected by their behaviors like wallowing in the mud, which helps them camouflage to their surroundings. The term “white” is believed to have originated from a misinterpretation of the Afrikaans word “wyd,” meaning “wide,” referring to the animal’s wide mouth, rather than its color. White rhinos are also the largest of the five living species of rhinoceros. In terms of its body mass, the white rhinoceros falls only behind elephants as the largest terrestrial mammal alive today.

Figure 9 : Morphological difference between white and black rhino

Black rhinoceros on the other hand have a colour that varies from brown to grey although they are referred to as black. The difference in the upper lip of black and white rhinos sets them apart as the white rhino is square-lipped and the black rhino is hook-lipped. The black rhino is smaller than the white rhino and close in size to the Javan rhino of Indonesia. Black rhinos are known for their aggressive behaviour. This can be seen in their behaviours such as charging readily at perceived threats and also, they have the highest rates of mortal combat recorded for any mammal. This is highlighted by the percentages of deaths that happen due to combat injury, where about 50 per cent of males and 30 per cent of females die from combat-related injuries.

The Indian rhino is the 2nd largest rhinoceros and they have a thick grey-brown skin with pinkish skin folds. They have one horn on their snout. On the other hand, Javan rhinoceros are one of the smallest rhinoceros species and their outer morphology is very similar to that of Indian rhinos due to the presence of skin folds but they are slightly smaller in size compared to Indian rhinos. Javan rhinos are among the rarest of all animal species in the world, with only one currently known wild population, and no individuals successfully kept in captivity.

Sumatran rhinos are also known as hairy rhinoceros because these animals have a patch of long hair around their ears and a thick clump of hair at the end of their tail along with a dense to scarce distribution of hair in their body.

Rhinos in general have a gestation period of 15 to 16 months on average. This results in females giving birth to just a single calf every 2 to 3 years. They also show delayed sexual maturity typically 5 to 7 years in females and 10 to 12 years in males. This results in a very low reproductive rate in these organisms. As poachers typically target adults this further declines the number organisms that can reproduce in a population. As a result, poaching has a devastating impact on rhinos due to their low reproductive rate.

Interesting facts about Rhinoceros

Rhinoceros are solitary animals with the exception of the bond between mother and calf. Due to their size, adult rhinos have no natural predators (other than humans), and even young rhinos are rarely attacked or preyed on due to the mother’s presence. These animals also have poor eyesight. Rhinos rely more on their other senses, such as hearing and smell, because their vision is not well-suited for seeing long distances. Objects far away tend to be blurry, which is why they charge if they feel threatened, especially if they can’t visually identify what is approaching. This deficiency is compensated with other senses like excellent sense of smell and hearing. Rhinoceros are herbivores and generally, their diet includes a high intake of fibrous plants and grasses along with the need to have regular access to water for drinking and wallowing. They consume more than 50kg of vegetation per day. When the aggressive nature of the two families of rhinos is compared, the rhinos from Africa are more aggressive than the family of rhinos from Asia.

Figure 11: Calf by the side of a mother rhino

Figure 12: A charging Rhino for a perceived threat

Ecological contributions of rhinoceros

Although rhino is not an apex predator it is considered to be a keystone specie due to the overwhelming effect it has on other organisms within the ecosystem. These giant herbivores substantially modify the habitat around them by their behaviours such as wallowing in mud puddles. This helps in creating natural waterholes and also keeps existing waterholes open. This action of wallowing causes a significant amount of mud, which are actually fertile alluvial soil that have accumulated in dams to be attached to their body. When these are dried or rubbed off as the animal moves to different location it helps distributing this fertile soil into places the animal move. The wallowing which creates mini wallow dams around the main dam gives protection to animals such as tambourine doves from predators as they don’t have to reach the main dam to drink water. These mini dams also help small animals like antelopes to drink water with less chance of getting stuck in mud.

These organisms also play an important role in complex food chains. For example, the consumption of more than 50kg of vegetation results in a deposition of more than 20kg of dung per day. Apart from the fertility, this dung adds to the soil, it also provides a substrate for the dung beetles to lay their eggs in a dung ball and bury it. The larvae that develop from this dung are a food source for large birds such as Crested guineafowl. This is one of the many food chains these magnificent organisms foster in the wild.

These horned grazers consume a very large amount of vegetation, which helps to shape the landscape that they live in.

Regardless of their importance to the ecology or the benefits they have on humans like the income generated due tourism, no species should go extinct due to irresponsible behaviours of man.

Human activities that have driven rhinos to the verge of extinction

“The scary thing is that in my lifetime, 95 percent of the world’s rhinos have been killed.”
– Mark Carwardine

According to the summary given under the topic of distribution and IUCN categorization for each rhinoceros species, it is quite evident that the rhino populations worldwide are in a perilous state. The primary cause of this crisis for these majestic creatures of the wild is reckless human activities such as poaching and illegal hunting. Rhinos are killed for their horns that are used in traditional medicine in some Asian countries and also, they are used as a status symbol in some cultures. The increased demand for rhino horns and the very low availability of rhinos in the wild drives the price of a horn more and more high. This drives people with lower income to grasp the opportunity of killing rhino and change their life for the better by selling the horns obtained for a substantial amount of money.

Figure 15: Recreational hunting of rhinos

Figure 16: A rhino being hunted for its horn

Apart from poaching and illegal hunting clearance of land for human settlement, agriculture and infrastructure development have led to the loss of habitat for these organisms. The images 7 and 8 shows how the ancient extensive distribution of these organisms have now been reduced to scattered patches in the wild. This results in loss of forage to satisfy the large dietary needs of those animals and reduced water sources which they need for their requirements such as drinking and wallowing. These isolated populations can result in reduced genetic diversity due to inbreeding which makes the population more susceptible to diseases.

Although inhumane and selfish human behaviours have pushed these animals to the verge of extinction, the sense of protection, humanity and the selflessness of human beings is what has saved these rhinos from completely disappearing from the face of our earth.

Conservation efforts

“Gland, Switzerland, 19 March 2020 (IUCN) – The African Black Rhino remains Critically Endangered, but its population is slowly increasing as conservation efforts counter the persistent threat of poaching, according to today’s update of the IUCN Red List of Threatened Species.”

The above statement highlights the impact of one of the conservation efforts. This positive result was achieved by continuous law enforcement efforts to prevent or reduce poaching, which is one of the main causes of rhino extinction.

Rhinos are also listed under CITES, which prevents trade of rhinos in the international market. But this hasn’t retarded the black-market demand and supply for rhino horns. CITES is an international treaty that monitors and restricts the trade of vulnerable flora and fauna. CITES restricts international trade of species that are threatened with extinction, and helps enforce trade restrictions to combat illegal trafficking. These types of collective international response to protect a specie like rhino that is about to go extinct, is crucial for the very survival of these organisms.

According to a 22^nd September 2023 Guardian article global effort to conserve rhinos have resulted in a rise in the global population count of rhinos to a number estimated around 27000. This rise reflects a positive trend in white and black rhinos. However, the Javan and the Sumatran rhinos remain critically endangered. According expert estimates the Sumatran rhinos are around 34, scattered in the wild. While there are reasons for optimism in the conservation efforts carried out globally, urgent action is needed to address the critical situation faced by endangered rhinos.

In conclusion, World Rhino Day serves as a powerful reminder of the urgent action needed to protect these majestic creatures. Although, Rhinos play a crucial role in maintaining the balance of ecosystems, they continue to face threats from poaching and habitat loss. While conservation efforts have shown signs of success, with some species showing recovery, the battle is far from over. On this day, we are called to take action, raise awareness, and support the global efforts to ensure that future generations can witness the incredible legacy of the rhinoceros. Together, we can help secure a future where rhinos thrive once again.

Written by:

Zainab Azar

Biological Science stream

1^st year

Faculty of Science

University of Colombo.

References