Namdapha flying squirrel (Biswamoyopterus biswasi)

GenusBiswamoyopterus (1)
SizeHead-body length: 405 mm (2)

Classified as Critically Endangered (CR) on the IUCN Red List 2007 (1).

The wonderfully peculiar Namdapha flying squirrel is the only species in the genus Biswamoyopterus (2). Like other flying squirrels, the most distinctive feature of this species is the furred, muscular membrane that extends along the sides of the body, from the front limbs to the hindlegs. This unique membrane acts as a parachute when the animal leaps from a tree, and once in the air, the squirrel can steer by moving its limbs and tail, and altering the tension in the membrane (3). The thick, soft pelage is red, grizzled with white, on the back, and white on the underparts. The fur covering the small hands and feet are darker. The Namdapha flying squirrel’s bushy tail is pale smokey-grey at the base, turning wine red, then reddish-brown and finally clove brown at the tip. At the base of each ear are tufts of long hair (2).

Occurs in a small area in the eastern Himalayas, north-east India (4)

The Namdapha flying squirrel inhabits temperate broadleaf forests (4). One specimen was found in a lofty tree, at 350 metres above sea level (2).

As the Namdapha flying squirrel has rarely been recorded, there is little information available regarding its biology or ecology, but it is likely to be similar to other flying squirrels. All flying squirrels are nocturnal, possibly because their movement is hindered when on trees by their gliding membrane, and thus the cover of darkness gives them extra protection from predatory birds-of-prey, from which they cannot easily run. However, the membrane does allow an effective escape from flightless tree predators. Launching themselves from a tree, flying squirrels descend in a long, smooth curves to the base of tree trunks, where they break by turning the body and tail upwards (3). Flying squirrels are known to consume a largely vegetarian diet of nuts, seeds, fruits and flowers and sap, and occasionally fungi, and usually bear one litter each year, containing, on average, one to six pups (3).

This little-known flying squirrel has a very restricted range, and is currently known from only one location (1). Like other restricted-range species, this makes it particularly vulnerable to any threats, which could rapidly affect all individuals in the population. The Namdapha flying squirrel is presently threatened by habitat loss and degradation (1), caused by clear-felling for human settlements, shifting agriculture, and the extraction of non-timber forest products, particularly the leaves of a rattan palm, Zalacca secunda, for use as a roofing material (5).

The Namdapha flying squirrel occurs within Namdapha National Park in Arunachal Pradesh (4). Despite the protection of this large area, it is still affected by human activities, such as those mentioned above. The Namdapha National Park contains not only the Critically Endangered Namdapha flying squirrel, but is also home to populations of other threatened species, including tigers (Panthera tigris), snow leopards (Uncia unicia) and Asian elephants (Elephas maximus). The effective protection of the Namdapha National Park is therefore incredibly important, but this is also an incredibly difficult aim to achieve. This is not only due to the park’s inaccessibility, the lack of legal enforcement and shortage of well-trained and equipped personnel, but also due to the local people’s dependence on the forest and the materials it provides. This means that any conservation measures require local people’s participation to be successful (5).

For further information on biodiversity and conservation in the Eastern Himalayas Region see:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. IUCN Red List (June, 2007)
  2. Nowak, R.M. (1991) Walker’s Mammals of the World. Fifth Edition. The John Hopkins University Press, Baltimore and London.
  3. Macdonald, D.W. (2006) The Encyclopedia of Mammals. Oxford University Press, Oxford.
  4. WWF-US, Asia Program. (2005) Ecosystem Profile: Eastern Himalayas Region. Critical Ecosystem Partnership Fund, Arlington, USA. Available at:
  5. Arunachalam, A., Sarmah, R., Adhikari, D., Majumder, M. and Khan, M.L. (2004) Anthropogenic threats and biodiversity conservation in Namdapha nature reserve in the Indian Eastern Himalayas. Current Science, 97(4): 447 - 454.