Squirrels of the World

Tamiasciurus hudsonicus 81

T. h. columbiensis—southern Yukon to central British Colum-
bia and southwestern Alberta (Canada). This form is
paler in color than T. h. streatori, with less black and red
on the tail.
T. h. dakotensis—southeastern Montana, northeastern Wyo-
ming, and western South Dakota (USA). It is larger and
paler than T. h. hudsonicus, with the underparts light yel-
lowish rufous and paler yellow in summer.
T. h. dixiensis—southwestern Utah (USA). This form is a
large subspecies. It is dark in color, with little yellow suf-
fusion of the pelage.
T. h. fremonti—Colorado (USA). In winter it is gray with a
rusty yellow cast on the back and grayish white under-
parts; in summer it is yellowish gray above and whitish
to grayish below.
T. h. grahamensis—Mount Graham, in southern Arizona
(USA). This form is similar to T. h. mogollonensis, but with
more yellow and less red above in its summer pelage.
T. h. kenaiensis, T. h. petulans, T. h. picatus, and T. h. lanugino-
sus (subspecies listed north to south)—along coastal
Alaska (USA) and British Columbia (Canada), including
Vancouver Island. These are similar to T. h. hudsonicus,
but diff er variously in being brighter or darker dorsally
and more yellowish below.
T. h. lychnuchus—central New Mexico (USA). This form is
similar to T. h. fremonti, but more red or yellow red
dorsally.
T. h. mogollonensis—Arizona and New Mexico (USA). This
form is large, with yellowish rufous coloration above.
T. h. preblei—south of the tundra in Alaska (USA) and north-
ern Canada, as well as in Alberta and Saskatchewan
(Canada). It is larger than T. h. hudsonicus, with paler col-
oration above and below.
T. h. richardsoni—southeastern British Columbia (Canada),
and western Oregon, central Idaho, and western Mon-
tana (USA). It is large, with a dark upper surface on the
tail and body and white underparts.
T. h. streatori—southern British Columbia (Canada), and
eastern Washington and northern Idaho (USA). This
form diff ers from T. h. richardsoni by a more olivaceous
coloration above in summer and less black on the tail.
T. h. ventorum—eastern Wyoming, extending west into
Idaho, north into Montana, and south into Utah (USA).
This form is darker and more olivaceous above than T. h.
baileyi, as well as blacker on the upper side of the tail and
grayer on the lower surface of the tail.

conservation: IUCN status—least concern. Population
trend—stable. The subspecies T. h. grahamensis is listed as
endangered under the U.S. Endangered Species Act, and as

critically endangered by the IUCN. Other subspecies are not

listed by the IUCN.

habitat: Red squirrels in North America (also known as

pine squirrels) are most common in boreal coniferous for-

ests with abundant conifer seeds, interlocking canopies for

effi cient foraging and escape from predators, and cool moist

conditions, which facilitate fungal growth and cone stor-

age in larders (middens). In the southeastern portion of its

range, T. hudsonicus also occupies a variety of other, less op-

timal forest types, including mixed coniferous-deciduous

forests, hedgerows, parks, and even hardwood forests with

scattered conifers. In these more marginal habitats, the pri-

ma r y deter m i na nt s of t rap success were herbaceous densit y,

canopy cover, and proximity to tree cavities, underground

burrows, and logs. In the southwestern portion of the range,

the animal occupies subalpine forests down through mixed

conifer forests and occasionally the transition zone between

ponderosa pine (Pinus ponderosa) and Douglas fi r (Pseudotsuga

menziesii) forests.

natural history: Red squirrels are diurnal; they show

bimodal periods of activity in spring and summer, but in

winter the animals are active only in midday. Activity out-

side the nest is devoted almost entirely to food gathering,

maintenance behavior (resting and grooming), and feeding.

Their activity is reduced by severe weather or abundant

food sources. Red squirrels are primarily granivorous, but

they are opportunistic feeders in the absence of mast foods.

Primary diet items vary with habitat and include the seeds

of conifers, oak (Quercus), hickory (Carya), beech (Fagus),

walnut (Juglans), yellow poplar (Liriodendron tulipifera), syca-

mores (Platanus), and maple (Acer). Both epigeous (aboveg-

round) and hypogeous (underground) mycorrhizal fungi are

Tamiasciurus hudsonicus. Photo courtesy Bruce D. Taubert.