The mouse-deer in Bangladesh: confirmed nowhere, rumoured everywhere

Greater mouse-deer, larger than its lesser relative, this species inhabits lowlands forests and riverine habitats of Southeast Asia. Photos: Collected

It is no bigger than a house cat, walks on impossibly thin, tin-can legs, and vanishes at the slightest sound. Many who have worked in South and Southeast Asian forests for years have never seen one in the wild. Yet it has always been there — the mouse-deer.

Despite its name, the mouse-deer is neither a mouse nor a true deer. It belongs to an ancient lineage of hoofed mammals known as chevrotains, family Tragulidae — a group so old and so unchanged that biologists sometimes call them living relics. 

In Bangladesh, the animal most people mean when they say "mouse-deer" is the lesser mouse-deer, or lesser Malay chevrotain (Tragulus kanchil), though several closely related species occur across the region and are easily confused with one another.

A lineage older than the Himalayas

The chevrotains' lineage stretches back more than 30 million years, making them among the most primitive ruminants alive today. While their distant cousins — deer, cattle, giraffes — evolved elaborate headgear and complex social structures, chevrotains remained essentially the same. No antlers. No horns. Instead, males carry elongated upper canine teeth, small, curved tusks used in territorial disputes, their only concession to ornament.

Adults typically weigh between two and five kilograms. Their build is unusual: legs so slender they seem barely adequate to the task of carrying even that modest weight, a body arched like a drawn bow, hooves the size of a child's fingernail. Their coat — warm brown, flecked with pale streaks and spots — breaks up their outline perfectly in dappled forest light. From snout to hoof, they are built for invisibility.

Chevrotains are primarily nocturnal, moving quietly along well-worn forest trails in the hours before dawn and after dusk. They are solitary by nature, communicating through scent markings and soft vocalisations that carry barely any distance at all. Most of their lives unfold in dense understorey, in the narrow gap between the forest floor and the lowest canopy, where human eyes rarely penetrate, and camera traps catch only the occasional blur of legs and eyeshine.

Small animal, large role

It would be a mistake to treat small size as a measure of ecological importance. Mouse-deers are significant seed dispersers — they consume fallen fruits and pass viable seeds through their digestive tracts, contributing to forest regeneration and plant diversity in ways that are difficult to quantify but easy to lose. Remove them, and the effects ripple slowly but surely through the understorey.

They are also prey. Pythons, leopards, clouded leopards, civets, and large raptors will all take a mouse-deer. In ecosystems where large predators have declined, the removal of this pressure can shift small ungulate populations in unpredictable ways — sometimes upwards, sometimes making them more exposed to opportunistic human hunting precisely because they are no longer skittish from predation. The dynamics are complex, and our understanding of them remains thin.

There is no confirmed specimen, no verified photograph, and no camera-trap record from within Bangladesh's borders.

Across Southeast Asia, chevrotains have long occupied human imagination as well as forest. In Malay and Indonesian folklore, "Sang Kancil" — the mouse-deer — is the great trickster, a creature of cunning rather than strength, forever outwitting tigers and crocodiles through sheer cleverness. The stories are fond, even admiring. Intelligence, they suggest, is more valuable than size. It is a fitting reputation for an animal that has outlasted so many of its larger contemporaries simply by being difficult to find.

The question of Bangladesh

Here, the story becomes murkier — and it is important to be precise about what we actually know.

Historical checklists and regional mammal surveys occasionally mention the possible occurrence of chevrotains in Bangladesh, particularly in the forested northeast and southeast, where habitats are ecologically continuous with parts of northeast India. There are also scattered references to village groves and remnant forest patches that might once have supported such species. But did any tragulid ever establish a population within what is now Bangladesh? And if so, does anything remain?

The truthful answer is simple: we do not know.

There is no confirmed specimen, no verified photograph, and no camera-trap record from within the country's borders. Absence of evidence is not evidence of absence — especially for a small, nocturnal, forest-dependent ungulate that moves silently through dense understorey and is notoriously difficult to detect. It is entirely possible that mouse-deer once persisted in small numbers in overlooked forest patches and disappeared before modern wildlife surveys began. It is equally possible that they never occurred here at all.

Complicating matters further is a long-standing confusion in local records. "Mouse-deer" has sometimes been used loosely in folklore, informal accounts, and even older scientific literature to describe different small ungulates. Without verified specimens or photographs, it is impossible to know which species — if any — those historical references were actually describing. This problem is not unique to Bangladesh; it runs through much of the subcontinent's early mammal literature. But here, it makes establishing historical occurrences particularly difficult.

A similar fog of uncertainty surrounds two other small mammals sometimes conflated in popular imagination: the hispid hare and the pygmy hog. Both are real, highly threatened species of the greater Brahmaputra floodplain grasslands — a very different habitat from the forest understorey required by chevrotains. Both have the absent status in Bangladesh. But they are not mouse-deer, and the ecological stories they represent are entirely separate. Grouping them together reflects a broader tendency to bundle overlooked small mammals into a single category of the unknown — a habit that serves none of them well from a conservation standpoint.

There is another layer to the confusion. Alongside discussions about the lesser mouse-deer in the northeast, recurring informal claims point to chevrotains in scrub and wetland-edge forests near the Sundarbans and the lower Ganges–Padma region. These claims usually circulate with photographs — but the images often depict Southeast Asian populations of the lesser mouse-deer, not animals from the Indian subcontinent. If a chevrotain were to occur in that Bangladeshi landscape, the more plausible candidate would be the Indian spotted chevrotain, whose confirmed range includes parts of India, with the closest records near the Indian Sundarbans just across the border. Whether it has ever crossed into the Bangladesh portion of that ecosystem remains unverified. The claims circulate; the evidence does not.

So where does this leave us?

The mouse-deer remains, for Bangladesh, an open question — neither a confirmed resident nor a confirmed loss. That may be uncomfortable, but it is the most scientifically honest position available. It also highlights a practical gap. Systematic surveys across the Chittagong Hill Tracts, the forests of Sylhet, and remnant woodland and scrub near the Sundarbans could, in principle, resolve several of these uncertainties. The data do not exist not because the questions are unanswerable, but because diminutive, inconspicuous species have rarely been the focus of targeted surveys.

Silence is not always absence — but it is not presence either.