A Japanese forest squirrel that glides between trees. It is mainly active in the treetops at night.
Its back ranges from silvery gray to buff-gray, with a pale belly. A gliding membrane extends between the wrists and ankles.
Japanese flying squirrels sometimes nest alone and sometimes share a tree cavity. In Nagano's northern Kiso Mountains, at 1,000–1,200 meters elevation, researchers monitored three cavities from December 2017 to November 2019 with camera traps, testing whether communal nesting was linked to temperature. Two cavities were in Japanese cedars and one in a Japanese cypress.
Direct observations from October to December 2019 recorded up to nine squirrels using one cavity. The cameras recorded 2,559 videos, and communal nesting was observed on 184 nights across the three cavities. During the 2018–19 snowy season, the daily maximum number in a cavity showed no relationship with ambient temperature. The footage recorded solitary and communal use in the same mountain forest.
Miyazaki Prefecture Red List · Endangered IB (EN-r) · Miyazaki Prefecture, Japan
The 2025 fiscal-year revision of the Miyazaki Prefecture Red List, published in 2026, lists the Japanese flying squirrel as EN-r, a regional Endangered IB category. EN-r covers species that were already rare locally and now remain at only two to four sites in very small numbers.