94 Glaucomys sabrinustail is uniformly gray, without rufescence, and darker on
the apical third of the tail.
G. s. oregonensis—coastal regions of southern British Colum-
bia (Canada) and Washington and Oregon (USA). Known
as the Bachman fl ying squirrel, this form is redder than
G. s. zaphaeus, with the upperparts being dark reddish
brown, and the underparts cinnamon or buff.
G. s. reductus—midcoastal area of British Columbia, near the
Koeye River, and inland toward Wisteria and Chezacut
(Canada). Known as the Atnarko fl ying squirrel, this
form is paler, less red on the dorsal surface, and whiter
on the ventral surface. It has clear gray cheeks.
G. s. stephensi—USA, in the “coast region of northern Cali-
fornia; limits of range unknown” (Howell). Known as
the California coast fl ying squirrel, this form’s reddish
upperparts are intermediate between G. s. lascivus and G.
s. oregonensis. More precisely, the upperparts are wood
brown, and the underparts are whitish with irregular
washes of light pinkish cinnamon.
G. s. yukonensis—interior of the Yukon, near the Yukon River
region (Canada), and west toward Tanana, Alaska (USA).
Known as the Yukon fl ying squirrel, this form is larger
than the typical G. sabrinus, with a longer tail and a
broader hind foot. The upperparts are cinnamon, pink-
ish to vinaceous.
G. s. zaphaeus—Canada and USA, in the “coast region of
southeastern Alaska and northern British Columbia;
limits of range unknown” (Howell). Known as the Alaska
coast fl ying squirrel, this form resembles G. s. alpinus, but
G. s. zaphaeus has browner upperparts and darker under-
parts. The eye ring is blackish.
conservation: IUCN status—least concern. Population
trend—stable.
G. s. coloratus is listed as endangered by the U.S. Endan-
gered Species Act.habitat: The northern fl ying squirrel is found in a variety
of forest types, but it is most often associated with boreal
conifer forests or mixed stands with a signifi cant conifer
component. Although previously considered a specialist of
primary forests, there is increasing evidence that this spe-
cies is a habitat generalist. In the Appalachian Mountains
(from New York state to northwestern Georgia [USA]), G.
sabrinus is often associated with spruce (Picea), fi r (Abies),
and hemlock (Tsuga); but it can also be found in mature de-
ciduous forests of yellow birch (Betula alleghaniensis), sugar
maple (Acer saccharum), beech (Fagus), and oak (Quercus). Nu-
merous reports suggest that there is considerable variation
and fl exibility in the habitat types used by this species
throughout its range.natural history: Although the northern fl ying squirrel
consumes seeds and nuts of both conifers and hardwoods,
it is considered less granivorous than G. volans and may be
an obligate mycophagist in many parts of its range, often con-
suming large quantities of hypogeous (underground) fungi,
especially at certain times of the year. As a mycophagist, it
may serve a keystone role in some forests by dispersing fun-
gal spores and inoculating tree roots. G. sabrinus also con-
sumes tree buds, catkins, staminate cones, tree sap, and ani-
mal material (such as songbirds, bird eggs, and insects), as
available. The northern fl ying squirrel is generally noctur-
nal, but it is also active either shortly before or after dawn
and immediately after sunset. This species moves terrestri-
ally and by gliding short distances, usually less than 20 m.
Details of its gliding performance and kinematics are re-
ported in the literature. G. sabrinus is active throughout the
winter and often nests with conspecifi cs to conserve en-
ergy, but it does not appear to show the same physiological
adaptations for dealing with extreme cold that are observed
in G. volans. Vocalizations are common when interacting
with conspecifi cs or when disturbed, but details on the con-
text and function of its vocalizations are not available. This
species builds nests in cavities, but it also constructs dreys
of most available materials: twigs, bark, moss, lichens, and
roots. Cavities are preferred in colder climates. The insides
of nests are lined with fi nely shredded material to provide
insulation, typically allowing an occupied nest to be main-
tained above 27°C, even when outside temperatures are as
low as 4°C.
Details of courtship and copulation are reported in the
literature and appear similar to those observed in G. volans.
Gestation is 37–42 days; litters range in size from one to six,
but usually average two to four. As many as three litters perGlaucomys sabrinus. Photo courtesy Phil Myers, Animal Diver-
sity Web, animaldiversity.org.