Dear Reader,
In December 2024, I made a short trip to Kaziranga National Park, a mosaic of grasslands, wetlands, and mixed forests, girded by the Brahmaputra to the north, and the Karbi-Anglong range to the south. I was revisiting the park after thirteen years, yet I had vivid memories of the landscape, with the Brahmaputra stretching out as far as the eye could see. During the winter months, the landscape plays host to numerous migratory birds. With the year-long residents like the one-horned rhinos, the Asiatic water buffaloes, the Asian elephants, eastern swamp deer and the Royal Bengal tigers, Kaziranga offers a grand wildlife experience!
Yet, if we were to look at the distribution of Kaziranga’s wildlife, we’d find that it is part of a wider corridor that links ecoregions across south and southeast Asia. In this edition, I would like to explore the landscape of Kaziranga, not just as a mosaic of habitats, but also, as a habitat corridor. By looking at where else some of Kaziranga’s iconic species are found, I want to trace present-day and past corridors, and expand our understanding of habitats beyond the protected and political boundaries we’ve created.
The Kaziranga Landscape
The word ‘Kaziranga’ stems from the Karbi language, spoken by tribes in the region. Several legends and local stories are said to explain the origins of the word: it was perhaps named after a childless couple, Kazi and Rangai, or from the words meaning ‘land of the red goats (hog deer, in this instance)’, or a woman ruler named Kajir Ronghangpi.
Over the years, Kaziranga began as a reserve forest to protect the one-horned rhinos, was then declared a game sanctuary, and shortly after, a wildlife sanctuary. In 1985, Kaziranga was inscribed as a UNESCO World Heritage Site for its incredible riverine patterns and as the world’s major stronghold of the Indian one-horned rhino, harbouring over 67% of the global population. Kaziranga has the second-highest density of the Royal Bengal tiger (or, as the locals call them, the golden tiger), and was also declared a tiger reserve in 2006. For the entomologists, it is also the second-largest habitat for butterflies, after Namdapha.
As per a 2020 land-use study, the Kaziranga National Park extends roughly 884.44 km2 and represents a mosaic of vast alluvial grasslands peppered with broad reed-lined pools, fringed by patches of deciduous and semi-evergreen forests. The seasonal flows of the Brahmaputra River and the summer wildfires are important factors that shape the landscape — the floods bring essential alluvium to the plains, while the wildfires are crucial for the regeneration of the grasslands. Today, controlled burning is conducted across the landscape in order to preserve the critical habitat, yet the river’s fluctuations can wildly alter the landscape between seasons.
The park’s geography is defined by the river and the range, as well as the human habitation and infrastructure around it. There are numerous settlements that thrive on tourism, with some folk employed by the extensive tea plantations of the Karbi-Anglong range. Highway 37, an arterial road connecting Assam’s capital, Guwahati, to other northeastern cities and towns, carves its way across the wildlife corridor. The human-wildlife incidents have been on the rise, as have roadkills. Other threats to the landscape include poaching, mainly of the one-horned rhinos, which has decreased considerably due to the park’s strict patrolling, livestock grazing in newly included parts, invasive species, and riverbank erosion.
Today, the wildlife we see in Kaziranga represents a smaller, fragmented population of what once was. By connecting the dots between occurrences of different species, we may hazard at past landscapes and the corridors that once existed.
The One-Horned Rhino (Rhinoceros unicornis)
Eocene fossils, dating ~56-33.9 million years ago, suggest that the Perissodactyla mammals, including horses, tapirs and rhinos, originated in the Indo-Pakistan region. Fossil records of the genus ‘Rhinoceros’ can be traced back 8-9 million years ago. During the Pleistocene (2.6 million years ago to roughly 11,000 years ago), the distribution may have stretched across southeast Asia, including Java island in Indonesia and as far as South China.
Modern rhinoceros emerged around 2.6-0.8 million years ago and have since inhabited the Indus, Ganges, and Brahmaputra River basins across the northern parts of the Indian subcontinent, all the way to Pakistan on the west and the Indian-Myanmar border, including Bangladesh and the southern parts of Nepal and Bhutan, to the east.
The Javan rhino, currently restricted to the Ujung Kulon National Park in Indonesia, was once present in north-eastern India through Myanmar, Thailand, Cambodia, Laos, Vietnam, and the Indonesian islands of Sumatra and Java. The Sumatran rhino was once found in the foothills of the Eastern Himalayas in Bhutan and eastern India through Myanmar, Thailand, possibly to Vietnam and China, and south through the Malay Peninsula. Yet today, it only resides in Indonesia's Sumatra and Borneo.
The one-horned rhino occupied much of the range of modern rhinos, but populations have dwindled since the post-Independence era, with local extinctions in the Lal Suhanra Park in Pakistan and, since the 1990s, in Bhutan’s Royal Manas National Park. According to a 1959 survey, there were about 260 rhinos across this landscape, and while the habitat may have shrunk, their numbers have risen to over 4000 at present.
Today, the one-horned rhino is found in seven national parks in India and in Nepal’s Chitwan National Park, with transient populations in a couple of others. After being poached to local extinction, two one-horned rhinos were seen in Laokhowa-Burhachapori Wildlife Sanctuary in Assam in December 2023. With government sanction and clearing out encroachers, this habitat may serve as a corridor between the Orang and Kaziranga. Read more.
The Malayan Giant Squirrel (Ratufa bicolor)
Modern tree squirrels, like the Ratufa, can be traced back 36 million years, and Asia’s genetic lineages seem to have diverged from other squirrels relatively early in the history of squirrel diversification, perhaps during a period of abrupt cooling and climatic fluctuation.
Interestingly, phylogenetic studies — the study of how groups of organisms are related to each other and how they evolved — indicate that giant squirrels’ coat colour evolved as a response to their habitats. Light-coated squirrels like the Pale Giant Squirrel and the Grizzled Giant Squirrel inhabit dry habitats. In contrast, dark-coated squirrels like the Indian Giant Squirrel and the Malayan Giant Squirrel are found in wet, dark habitats.
The Ratufa genus of giant arboreal squirrels is restricted to South and Southeast Asia. The Pale Giant Squirrel (Ratufa affinis) inhabits the forests of the Thai-Malay Peninsula, Sumatra, Borneo and nearby small islands. The Grizzled Giant Squirrel (Ratufa macroura) is restricted to the southern tip of India and Sri Lanka. The Indian Giant Squirrel (Ratufa indica) is endemic to India, and can be found in the Western and Eastern Ghats, and the Satpura Range. The largest of India’s giant squirrels, the Malayan or black squirrel (Ratufa bicolor), inhabits north Bengal, Sikkim, eastern Nepal, northeast India, north Bangladesh, Bhutan, south China, Myanmar, Laos, Thailand, west Malaysia, Cambodia, Vietnam and western Indonesia’s islands like Java, Sumatra, Bali, among others.
The Malayan Giant Squirrel is also found in Kaziranga’s western zone, which has thick, old-growth forests. Tracing its present-day distribution across South and Southeast Asia, one can get a sense of the rich swathes of tropical and subtropical forests that once covered these regions. These squirrels seem more restricted to the canopy than the other giant squirrels and haven’t been recorded venturing into tea estates or nearby fields, which makes them ideal ‘indicator species’ to help determine habitat quality across political divides.
Read more in this article on the Malayan Giant Squirrel by Aathira Perinchery for Mongabay India.
For anyone keen on continuing this exercise of mapping the present distribution of related species to understand current and past habitat corridors, the Western Hoolock Gibbon (Hoolock hoolock), also found in Kaziranga, would be ideal. Their range can be compared to that of the Eastern Hoolock Gibbon (Hoolock leuconedys) and the Skywalker Hoolock Gibbon (Hoolock tianxing) for a sense of evolutionary divergence.
Yet, as we didn’t spot any during our travel, and this edition has gotten lengthy enough, I won’t go into further detail.
In some sense, today’s species distribution is the result of a fragmented landscape — both ecologically and politically! With rampant habitat destruction and fragmentation, changing land use patterns, poaching, climate change and other anthropogenic threats, these populations are being further fragmented and genetically isolated. Given India’s geographical position, linking the habitats of Southeast Asia with those of South and Central Asia would be critical for conservation efforts.
For a broader perspective on landscapes and biodiversity, you could also map the distribution and migratory routes of birds — to understand the different habitats that allow them to survive. I’d written about bird migrations before.
The next time you record wildlife in a particular habitat, try to connect the dots between where else that species exists and where it may once have existed — for a deeper understanding of ecological corridors, in the past and present.