Tony Wu / Siberian flying squirrel (Pteromys volans orii) eating fresh needles of Sakhalin fir tree (Abies sachalinensis) during light snowfall. Hokkaido, Japan. February.

Tony Wu / Female Siberian flying squirrel (Pteromys volans orii) feasting on branch cut from nearby Sakhalin fir tree (Abies sachalinensis). Hokkaido, Japan. February.

Tony Wu / Siberian flying squirrel (Pteromys volans orii) peeking out of its nest in Sakhalin fir tree (Abies sachalinensis) in early winter morning light. Hokkaido, Japan. March.

Tony Wu / Female Siberian flying squirrel (Pteromys volansorii), having emerged to defecate snacking on Sakhalin fir tree (Abies sachalinensis) needles. Hokkaido, Japan. March.

Tony Wu / Japanese dwarf flying squirrel (Pteromys volans orii) sitting on tree trunk at night near nest hole. Hokkaido, Japan. March.