Pteromys volans have a membrane that extends between their fore- and hind limbs. Unlike some other species of flying squirrels, Pteromys volans do not have a membrane between their hind limbs and the base of their tail. Their limbs are relatively short and thick and their hind feet are significantly larger than their forefeet. The length of the head and body is 120-228 mm. Pteromys volans have distinct, large, black eyes. Old World flying squirrels have thick, long and soft fur. In the summer, the fur on the back is yellow-gray to blackish gray. In the winter, it becomes silvery gray. The belly remains white throughout the year. The margins of the gliding membrane are bordered with a distinct fringe of soft fur. The tail is flat and is covered with short hair.
(Nowak 1991, Ognev 1966)
Average mass: 130 g.
Habitat and Ecology
Populations of Pteromys volans can be found in forests with aspen, birch, spruce, cedar, or pine trees. They prefer areas with a lot of old, hollow trees for building nests. (Ognev 1966)
Terrestrial Biomes: taiga ; forest
Pteromys volans are basically herbivores. In the summer, they feed on green plants, young branches, berries and seeds. During the winter months, P. volans consume nuts, catkins, pine cones, and pine needles. Local hunters claim the Old World flying squirrels also eat young birds and eggs from nests. However, there is no scientific evidence of this behavior. (Niethammer 1990, Ognev 1966)
Life History and Behavior
Status: wild: 3.8 years.
Lifespan, longevity, and ageing
The information on the reproduction of Pteromys volans is contradictory and incomplete. The reproduction patterns may differ among subspecies. Pteromys volans has one or two litters a year each consisting of anywhere from 1-6 young. The most recent evidence states that they have two litters, each consisting of 2-3 young, one in May and the other in late June or early July. Gestation lasts for four weeks. (Corbet 1966, Niethammer 1990, Nowak 1991, Ognev 1966)
Average gestation period: 30 days.
Average number of offspring: 2.6.
Molecular Biology and Genetics
Statistics of barcoding coverage: Pteromys volans
Public Records: 0
Specimens with Barcodes: 2
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
Populations of P. volans are declining in Europe because of habitat destruction due to lumbering. (Nowak 1991)
IUCN Red List of Threatened Species: least concern
In Mongolia, habitat loss caused by selective logging, human-caused fires and natural wildfires in some parts of its range are a threat.
It is listed on the Chinese Red List as Vulnerable A1cd.
Relevance to Humans and Ecosystems
Siberian flying squirrel
The Siberian flying squirrel (Pteromys volans) is an Old World flying squirrel with a range from the Baltic Sea in the west to the Pacific coast in the east. It is the only species of flying squirrel found in Europe. It is considered vulnerable within the European Union where it is found only in Finland, Estonia and Latvia.
A female Siberian flying squirrel weighs about 150 grams, the males being slightly smaller on average. The body is 13–20 cm long, with a 9–14 cm long flattened tail. The eyes are large and strikingly black. The coat is gray all over, the abdomen being slightly lighter than the back, with a black stripe between the neck and the forelimb. A distinctive feature of flying squirrels is the furry glide membrane or patagium, a flap of skin that stretches between the front and rear legs. By spreading this membrane the flying squirrel may glide from tree to tree across distances of over a hundred metres, and have been known to record a glide ratio of 3.31, but is normally 1-1.5.
Its diet consists of leaves, seeds, cones, buds, sprouts, nuts, berries and occasionally bird eggs and nestlings. When alder and birch catkins are plentiful, the squirrel may store them for the winter in old woodpecker holes or similar nooks.
They mate early in the spring. In southern Finland the first mating season begins in late March, with a second mating season occurring in April. After a gestation period of five weeks, the female gives birth to a litter of usually two or three young, each weighing about 5 grams. They preferentially build their nest in holes made by woodpeckers, but they may also nest in birdhouses if the size of the entrance is appropriate. The nest consists of a pile of soft materials (preferably soft beard lichen) into which the squirrel burrows. They can live up to about five years.
They favour old forests with a mix of conifers and deciduous trees. They are mostly nocturnal, being most active late in the evening, although females with young may also feed during the day. They do not hibernate, but in the winter they may sometimes sleep continuously for several days. As shy and nocturnal animals, they are seldom seen. The most common sign of their presence is their droppings, which resemble orange-yellow rice grains and are often found beneath or on top of their nest.
- Shar, S., Lkhavgasuren, D., Henttonen, H., Maran, T. & Hanski, I. (2008). Pteromys volans. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 6 January 2009.