114 Petaurista leucogenysP. l. oreas—Wakayama, southern peninsula of the island of
Hondo (Japan). The upperparts are a rich brown, suf-
fused with rufous on the head. The underparts are
washed with buff y. The patch below the eye is dark ru-
fous, as is the forehead. The cheek patch is light dull
grayish washed with buff y. The tail is dull cinnamon.
conservation: IUCN status—least concern. Population
trend—stable.
habitat: P. leucogenys is found in mature stands of either
primary or secondary forests. Few other details are avail-
able on its habitat.
natural history: This species shows seasonal shifts in
its diet (from folivory to granivory), feeding on the parts of
at least 45 species of trees, yet it is reported to be highly se-
lective when foraging. Overall, its diet is estimated to con-
sist primarily of leaves (26%–40%), seeds (34%), and the sta-
minate cones of various conifers (12%). However, even pine
needles (Pinus) and cedar foliage (Cryptomeria japonica) are
included in small percentages. Although animal material is
occasionally consumed, this species is an obligate folivore,
especially at certain times of the year. It is also exclusively
arboreal and never hoards food. A nine-year study on the
diet of P. leucogenys revealed strong seasonal patterns of
food use: fl owers and leaves constitute the majority of the
diet in winter, spring, and early summer; seeds make up
most of the diet in late summer, fall, and early winter. Ma-
ture leaves are consumed most often during February and
again in July, at the same time that females are pregnant and
the availability of other foods is lowest. During lactation,
however, leaf consumption ceases. Their herbivorous diet is
aided by their ability to remain in a sitting position on
small branches while extending their forepaws to reach
branches with buds and leaves. Compared with smaller
squirrels, P. leucogenys spends more time foraging among
smaller branches, and it also spends more time feeding
while perched on vertical surfaces and smaller supports
relative to its body size. Possibly because its diet often in-
cludes a high percentage of plant material, feeding bouts are
relatively long, but they occur rather infrequently through-
out the day. This species is reported to have a large caecum.
Under natural conditions, P. leucogenys usually becomes
active about 30 minutes after sunset. Individuals show con-
siderable overlap in their home ranges. For nesting, they
often converge on mature forest patches, where nest cavi-
ties are available. One study reports that home range use is
not homogenous, but instead is concentrated in patches of
secondary forests, where food is abundant. Two mating sea-
sons are reported: one from mid-November to mid-January,
and another from mid-May to mid-June. Gestation is 74
days. The young begin feeding independently at 80 days
postpartum, and they are usually weaned by day 91. Studies
on their glide performance have reported average glide ra-
tios (horizontal distance/vertical height) of 1.87, with upper
limits of 3.5. The range of air speed was 4.39–9.47 m/second,
with 3.3–7.0 m/second recorded in two studies. Horizontal
glide distances in four study areas ranged between 10 and
100 m and averaged 17.1–33.1 m. Phylogenetic analyses based
on partial mitochondrial cytochrome b sequences indicate
that P. leucogenys and other members of the genus are more
closely related to Pteromys than to four other genera: Belo-
mys, Glaucomys, Hylopetes, and Petinomys. A study of genetic
variation in P. leucogenys across Japan identifi es three pri-
mary lineages: one from the island of Kyushu, a second con-
sisting of haplotypes from the islands of Kyushu and Hon-
shu, and a third defi ned by haplotypes from the islands of
Honshu and Shikoku. The genetic diff erences do not corre-
spond with geographic distances, but instead suggest recent
range expansions (since the late Pleistocene).general references: Andō and Imaizumi 1982; Andō
and Shiraishi 1993; Andō et al. 1984, 1985a, 1985b; Baba et al.
1982; Hiroyuki 1999; Ishii and Kaneko 2008a; T. Kawamichi
1997a, 1997b, 1998, 1999; Miayo 1972; Mori and Takatori 2006;
Nakano et al. 2004; Oshida 2006; Oshida, Hachiya, et al. 2000;
Oshida, Hiraga, et al. 2000; Oshida, Ikeda, et al. 2001; Oshida,
Lin, Masuda, et al. 2000; Oshida and Obara 1993; Oshida and
Yoshida 1999; Shafi que et al. 2006; Staff ord et al. 2002, 2003;Petaurista leucogenys. Photo courtesy Takeo Kawamichi.