World Rhino Day: Birds on white rhino's back

Photo: Pal Teravagimov/Shutterstock

Given the overwhelmingly imperiled status of the world's rhino species, it should come as no surprise to learn that there are multiple international holidays establish to celebrate these creatures and raise awareness for their plight. These holidays include Save the Rhino Day on May 1 and World Rhino Day on Sept. 22, which was established in 2010 to celebrate all five extant species of rhinoceros: Black, white, Sumatran, Indian and Javan.

These large, herbivorous animals are found in Africa, like the white rhino above, and Asia, like the Indian rhino below.

World Rhino Day: Indian Rhino grazing

Photo: David Evison/Shutterstock

Each species is unique, but all of these animals are dealing with major conservation threats caused primarily by poaching and habitat loss.

World Rhino Day: White rhinos and flamingos

Photo: javarman/Shutterstock

White rhino

After African and Asian elephants, the white rhino is the heaviest land mammal. Don't let their size fool you. While they might charge if they feel threatened (or if you're too close to their baby), these gentle giants would much rather roam the grasslands and savannahs of Africa, where they spend the majority of the day grazing. When they're not munching on vegetations or sleeping, they like to wallow in mudholes to cool off.

World Rhino Day: Mud bath

Photo: Francois van Heerden/Shutterstock

There are two subspecies of the white rhino, each with their own conservation difficulties. While the southern white rhino is the most abundant rhino species in the world (though, still threatened), the critically endangered northern white rhino is generally considered to be extinct in the wild.

As of 2011, it's believed there are only seven northern white rhinos left on the planet; three are in captivity while four are in conservancy.
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World Rhino Day: Black rhino under trees

Photo: senai aksoy/Shutterstock

Black rhino

The black rhino was once the most abundant of all the rhino species. In fact, it's estimated several hundred thousand black rhinos were living on the African continent around 1900. Sadly, after less than a century of relentless poaching and habitat destruction, these numbers dwindled to a shocking 10,000-15,000 individuals by 1981. Today, the numbers are even more troubling.

World Rhino Day: Black rhino trotting

Photo: HPH Photo Library/Shutterstock

It's generally accepted that there are seven or eight subspecies of black rhinos, though the majority of them are now extinct. The most recent subspecies to fall was the western black rhino, which was officially declared extinct by the IUCN in 2011. Today, the western black rhino population is comprised mostly of the south-central, eastern and south-western subspecies, though the Ugandan and Chobe subspecies may exist in single-digit numbers.

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World Rhino Day: Sumatran rhino

Photo: International Rhino Foundation/Wikimedia

Sumatran rhino

This critically endangered species is the smallest of all the rhinos. While a white rhino can weigh up to 5,000 pounds, a Sumatran rhino averages between 1,100 and 1,800 pounds. It's estimated that only about 275 Sumatran rhino currently remain, and the number will only grow bleaker as habitat loss and poaching continues unchecked.

World Rhino Day: Hairy Sumatran rhino

Photo: Ltshears/Wikimedia

The most noticeable characteristic that sets a Sumatran rhino apart from the other species is its rust-colored hair. As the most ancient extant species of rhino, the Sumatran rhino's genetics are closely related to the extinct woolly rhino (also known as Coelodonta), which lived during the Pliocene and Pleistocene epochs.

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World Rhino Day: Indian rhino in grass

Photo: Krish Dulal/Wikimedia

Indian rhino

The exaggerated armor-like skin folds and warty bumps are what really makes this rhino stand out from the rest of the rhinoceros family. Due to its single keratin horn adorning its snout, the species is also called the greater one-horned rhinoceros.

World Rhino Day: Indian Rhinoceros

Photo: ilovezion/Shutterstock

The Indian rhino's natural range once extended across the grasslands and forests between Pakistan and Burma. As their numbers have declined over the years due to human encroachment, the vulnerable species is now confined to governmentally protected areas in India, such as Kaziranga National Park. Today, there are only about 3,000 Indian rhino left in the wild.

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World Rhino Day: Javan sunda rhino

Photo: Wikimedia

Javan rhino

This animal, also known as the Sunda rhino, has the depressing distinction of being one of the most critically endangered mammals on the planet. The species once comfortably populated the dense lowland rain forests and grasslands all across southern Asia, but they were nearly hunted to extinction in the 1930s under the belief that their horns and blood possessed medicinal powers. The future does not bode well for them.

Today, only about 40 individuals are known to remain in Indonesia's Ujung Kulon National Park. They managed to cling to existence in Vietnam up until 2009, when the last known Javan rhino living in the country was found dead in Cat Tien National Park after poachers shot and removed its horn.

World Rhino Day: Javan rhino extinct

Photo: T.Dixon/Zoological Society of London

Because there are so few individuals left in the world, the Javan rhino is the least understood of the rhino species. What scientists do know is that it's most closely related to the Indian rhino, which is a bit larger. Unlike the other rhino species, the Indian and Javan rhinos only have one horn instead of two, which is why they are also known, respectively, as the greater one-horned rhino and the lesser one-horned rhino.

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Want to do something special in honor of rhinos today? Take a look at the video below to see how conservationists and animal lovers across the globe spent last year's World Rhino Day:

And why not kick off your mission to save the rhinos with a little research? Continue below to learn about each species, and visit and the International Rhino Foundation to learn how to get involved.
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Catie Leary is a photo editor at Mother Nature Network. Follow her on Twitter and Google+.