Namdapha Flying Squirrel

The Namdapha Flying Squirrel is one of the rarest and most enigmatic mammals on Earth, known from only a single specimen collected in 1981 in Namdapha National Park, India. It is a large gliding rodent adapted to tropical rainforest canopy life, using a patagium to glide between trees. Its extreme rarity and lack of subsequent confirmed sightings for decades make it a flagship species for Critically Endangered mammals of Asia.

Northeastern India (Arunachal Pradesh), specifically the Namdapha National Park region

Known only from the type locality near Namdapha National Park in Arunachal Pradesh, northeastern India, near the border with Myanmar; possible but unconfirmed range extension into adjacent Myanmar forests.

Altitude and depth

Approximately 200-1500 meters above sea level, within hill and lowland tropical forest zones.

Seasonal movements

No documented seasonal migration; presumed to be a year-round forest resident with possible increased activity during warmer, wetter monsoon months when fruiting is more abundant.

Tropical and subtropical evergreen rainforest with dense canopy cover, typically in undisturbed lowland to hill forest ecosystems within protected areas.

Adaptations to its environment

Possesses a furred patagium (gliding membrane) stretching between fore and hind limbs enabling long-distance gliding through dense canopy, reducing energy expenditure for arboreal locomotion. Large eyes suggest strong nocturnal vision adapted to low-light forest conditions.

Listed as Critically Endangered by IUCN due to its presumed extremely restricted range, potential extinction risk from habitat loss, and the fact that it has been recorded only once in over 30 years despite survey efforts.

Estimated population

Unknown; no reliable population estimate exists due to lack of confirmed sightings since the holotype was collected, trend presumed declining based on regional habitat loss.

Deforestation and habitat degradation from logging and agricultural encroachment, hunting for bushmeat by local communities, and the inherent vulnerability of a species with an apparently minuscule known range.

Namdapha National Park provides some legal habitat protection; renewed survey expeditions (including a notable 2004 rediscovery of a related specimen in a market, sparking interest) have aimed to confirm the species' continued existence.

Recommended actions

Intensive camera-trap and nocturnal survey efforts within and around Namdapha National Park, stronger anti-poaching enforcement, habitat protection expansion, and genetic studies of any newly found specimens to clarify taxonomic status.

Grayish-brown to reddish dorsal fur with lighter, creamy underparts, a long fluffy tail, and a wide gliding membrane connecting limbs; large dark eyes adapted for nocturnal vision.

Size

Estimated body length of 40-50 cm (head-body), with a long bushy tail adding an additional 45-50 cm, based on the single known specimen.

Weight

Estimated weight around 1.5-2 kg, based on comparison with related large flying squirrel species.

Distinctive features

Distinguished from its closest relative, the Laotian Giant Flying Squirrel (Biswamoyopterus laoensis), by subtle differences in skull morphology, fur coloration, and tail characteristics documented in the original 1981 description.

Presumed solitary or loosely social, consistent with most flying squirrel species, though behavior is entirely undocumented due to lack of field observations.

When it is active

Nocturnal, consistent with other flying squirrels, likely most active during dusk and nighttime hours when gliding between canopy trees.

Diet

Presumed herbivorous, likely feeding on fruits, seeds, nuts, leaves, and possibly bark or tree sap, based on the diet of related flying squirrel species.

Communication

Unknown; related flying squirrel species use vocal calls, scent marking, and body postures, which may also apply to this species.

Interactions with other species

Likely preyed upon by forest raptors, arboreal snakes, and small carnivores; may compete with other arboreal rodents and squirrels for food resources in the canopy.

Role in its ecosystem

Likely plays a role in seed dispersal and forest regeneration through fruit and seed consumption, contributing to the health of its tropical forest ecosystem.

Completely undocumented; presumed similar to related flying squirrels with likely one or two litters per year and small litter sizes of 1-3 offspring.

Raising the young

Unknown, but likely similar to other flying squirrels where the mother provides sole parental care, nursing young in a tree hollow nest until weaning.

Maturity and lifespan

Unknown; related flying squirrel species typically reach sexual maturity around 1 year of age with lifespans of 4-6 years in the wild.

Classification

Class Mammalia > Order Rodentia > Family Sciuridae > Genus Biswamoyopterus > Species Biswamoyopterus biswasi

Recent studies

A 2019 study confirmed the rediscovery of the genus Biswamoyopterus through a specimen found in a Laotian market, renewing hope that B. biswasi may still survive; genetic comparisons have helped clarify relationships within the genus.

Compared with similar species

Closely related to the Laotian Giant Flying Squirrel (Biswamoyopterus laoensis) and the Yunnan Giant Flying Squirrel (Biswamoyopterus fuscus), together forming a small, poorly known genus of giant flying squirrels distinguished by unique cranial and dental features.

Known from only a single museum specimen collected in 1981, making it one of the least-documented mammals in the world; the genus Biswamoyopterus was thought to contain only this one species for over 20 years until relatives were discovered in Laos and China.

Where and how to see it

Observation is essentially impossible given no confirmed sightings since 1981; any survey attempts should focus on nighttime canopy searches with spotlights and camera traps within Namdapha National Park during dry season months for better visibility.

Risks to humans

No notable risk to humans.

Human uses

No documented human use, though related flying squirrel species are sometimes hunted for bushmeat or traditional medicine in the region.