Tamiasciurus hudsonicus
(Red Squirrel)
Description:
The red squirrel, also known
as the chickaree, is brownish red to rust red on its upper half with a white
ventral side separated from the top by a dark stripe. It has a light colored
eye ring which is easy to see when observing the squirrel, and its tail is bushy
but not large and prominent like those of other tree squirrels, the outer edge
of the tail has a black band edged with white. Behaviorally, it is quick and
energetic with jerky and very busy movements.
Range:
From Alaska, east to Newfoundland,
south to Smoky Mountains, and south through Rocky Mountains to Arizona and New
Mexico.
Habitat:
The red squirrel is
found throughout the northern boreal forest across Canada and
the northern tier of states, much like the northern flying squirrel. They prefer
coniferous
and mixed forests, but
is frequently found in deciduous
woodlots, hedgerows, and
second-growth areas. Ideal habitat seems to be spruce-fir forests, and the seeds
in spruce cones especially are preferred. In Idaho, found in all coniferous
forests, mixed forests, and riparian
woodlands adjacent to
conifers. Young are typically forced into marginal, deciduous forests such as
aspen in Idaho.
Diet:
They commonly eat seeds of conifer cones, nuts, fungi, and fruits. Their
propensity to eat conifer seeds is a hallmark of their activity and influence
on forest ecosystems. They occasionally feed on invertebrates. Recent research
in Canada documented that they prey on bird eggs, young birds and even on newly
born snowshoe hares.
Ecology:
Like most tree squirrels
they are diurnal with peak activity in
morning 2 hours after sunrise and evening before sunset. They are usually conspicuous
throughout day. They are capable climbers and can easily leap from limb to limb.
Because they do not hibernate
they store food for the
winter. During a 4 to 6 week period in the fall, spruce, fir, and pine cones
are fully developed and the seeds in the cones are mature. Red squirrels cut
cones from conifer trees and cache
them in storage areas
called middens
. The middens, often 15
by 30 feet or even larger, are formed over numerous years by continuous storage
and feeding activity. As the midden owner feeds, rapidly extracting the numnerous
seeds from each cone with its teeth, the cone bracts are stripped off and fall
onto the midden. Many middens have a 12 inch layer of cone bracts on top of
moist soil. This medium provides an ideal location for the storage of many cones
in holes and depressions dug into the midden. Red squirrels also store cones
in small depressions in the ground away from their middens, Red squirrels do
all of their storing of cones during a 4 to 6 week period in the early fall.
If the cones are not cut from the tree during a critical period when the seeds
are fully developed, the bracts
of many cones open and
the seeds are dispersed by the wind. If they are cut from the tree and left
lying on the ground, the cones dry out and open up, again allowing the seeds
to disperse. Squirrels prevent this by storing the cones they cut in their moist
caches or middens, where they are tightly packed into holes like dill pickles
in a jar. Middens tend to be near the center of the squirrel's territory, which
is about .5 to 1.5 ha (1 to 4 acres). Red squirrels may be the most territorial
mammals in Idaho. During the fall cone cutting and storing creates a flurry
of activity that can result in the storage of up to 20,000 cones. Squirrels
will cut cones from near the tops of trees for 5 or 6 minutes, then descend
and carry them into their middens. They rarely carry cones farther than 30 yards
from their middens. Cone crop failures often force the squirrels to use year
old or older cones from their stores, but only the larger middens seem to hold
more than one winter's supply of food. The red squirrel's territorial call is
easy to hear and consists of a long churr---of 1 to 4 seconds duration. Similar
to territorial songs in birds, the squirrel's call advertises its presence in
its territory. Failure to periodically call usually results in an invasion of
territory by a neighboring squirrel. This behavior is most pronounced during
the fall food storing period, but it also continues throughout the year. They
commonly cache more food than it can consume in a winter, which leaves cones
for the next year in case of a cone crop failure. Early foresters in Idaho would
collect cones and their seeds from red squirrel middens for their tree nurseries.
This cone storing behavior also has economic value in seed dispersal in forests.
Population densities range from about 1/3.2 ha (Pinaleno Mountains, southeastern
Arizona) to 1/0.2 ha. More territorial than most other North American tree squirrels.
Populations in British Columbia are limited by food (acting through effect on
reproduction). Red squirrels are ecologically connected to grizzly bears in
Idaho. Red squirrels at higher elevations collect and store whitebark pine cones
in their middens. In the fall grizzlies seek out these middens where they eat
the whitebark seeds from the cones stored by the red squirrel. Of course that
is tough on the red squirrel who spent a great deal of energy storing up its
own winter food supply. But they cannot argue with a grizzly bear.
Reproduction:
Breeds March-April and June-July.
Female is in estrus only for 1 day. Gestation
lasts 31-35 days. Some
females produce 2 litters/yr. litter
size averages 4-5 young.
Some females breed when less than 1 yr old.
Conservation:
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Global Rank: |
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State Rank: |
S5 |
Important State References:
Medin, D.E. 1986. The impact of logging
on red squirrels in an Idaho conifer forest. West. J. Appl. Forestry 1:73-76.