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The Douglas Squirrel
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The Douglas squirrel (Tamiasciurus douglasii) is a pine
squirrel found in the Pacific coastal states of the United States as
well as the southwestern coast of British Columbia in Canada. It is
sometimes known as the chickaree or pine squirrel, although these names
are also used for the American red squirrel. Variant spellings of the
common name are Douglas' squirrel and Douglas's squirrel. The Native
Americans of Kings River called it the "Pillillooeet", in imitation of
its characteristic alarm call.
John Muir described the Douglas
squirrel, Tamiasciurus douglasii, as "by far the most interesting and
influential of the California Sciuridæ". Adults are about 33 cm in
length (including its tail, which is about 13 cm long), and weigh
between 150 and 300 grams. Their appearance varies according to the
season. In the summer, they are a grayish or almost greenish brown on
their backs, and pale orange on the chest and belly, while legs and feet
appear brown. In the winter, the coat is browner and the underside is
grayer; also, the ears appear even tuftier than they do in summer. Like
many squirrels, Douglas squirrels have a white eye ring.
Mating
can occur as early as February. Gestation is about four weeks, and the
young (which are altricial) are weaned at about eight weeks of age.
There may be up to six kits in a litter, though four is more usual. In
the southern and lower parts of their range they produce two litters
each year.
Douglas squirrels live in coniferous forest habitats
along the Pacific Coast, from the Sierra Nevada (mountains) of
California, northwards to the southwestern coast of British Columbia.
Tamiasciurus douglasii prefer old-growth forests or mature second-growth
forests, and some authors regard them as dependent on its presence.
They are territorial; in winter, each squirrel occupies a territory
of about 10 000 square metres, but during the breeding season a mated
pair will defend a single territory together. Douglas squirrels are
active by day, throughout the year, often chattering noisily at
intruders. In summer nights, they sleep in ball-shaped nests that they
make in the trees, but in the winter they use holes in trees as nests.
Groups of squirrels seen together during the summer are likely to be
juveniles from a single litter.
Douglas squirrels mostly eat
seeds of coniferous trees such as Douglas fir (Pseudotsuga menziesii),
Sitka spruce (Picea sitchensis) and shore pine (Pinus contorta). They
also eat acorns, berries, mushrooms, the eggs of birds such as yellow
warblers, and some fruit including strawberries and plums. Douglas
squirrels are larder hoarders, storing their food in a single location
or 'larder' called a midden. As the squirrel peels the scales off cones
to get at the seeds, the discarded scales accumulate into piles that can
grow to more than a meter across as the same site is used by generations
of squirrels.
Their predators include American martens, bobcats,
domestic cats, northern goshawks, and owls; although they quickly
acclimatise to human presence, humans can be a threat to them, through
robbing of their cone caches to find seeds for tree cultivation and
through the destruction of old growth forest. However, the squirrels'
numbers appear to be unaffected by commercial thinning of forests. |
Sources
Sources for this article include:
•
"Tamiasciurus douglasii". IUCN Red List of Threatened Species. Linzey,
A. V. & Hammerson, G. (2008). . International Union for Conservation of
Nature.
Any contributions will be
gratefully accepted
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