Land Mammals of British Columbia: Squirrels

British Columbia's squirrels are found in the deepest forests, and crossing Vancouver's busy streets on power lines. Some are active by day, and others emerge only under cover of darkness. They are members of the rodent family, and each has a story to tell.

The Red Squirrel (Tamiasciurus hudsonicus) is the most widely distributed squirrel in Canada.

This small squirrel (they average about 230 grams) is superbly adapted to a life in the coniferous forest. Fast and agile, the Red Squirrel can jump great distances, and even run along the undersides of branches. Their pelage in summer is olive brown above, but it moults to a redder colour in the fall. It is found throughout most of British Columbia, including Vancouver Island. It is absent from Haida Gwaii, the former Queen Charlotte Islands, and, curiously, a small coastal strip in the lower mainland.

Here, it is replaced by the Douglas Squirrel, or Chickaree (Tamiasciurus douglasii), whose yellow underparts are quite different. The two species are found together on Cortez Island, between Vancouver Island and the mainland. The genus name of both species means "the steward who sits in the shadow of his tail", a reference to their habit of curling the tail over the back. Both species are diurnal, foraging during the day on vegetable matter, primarily seeds and cones. They are active even in very cold weather, though they may wait out a severe storm in the comfort of their den, a burrow in the ground.

Their larger cousin, the Gray Squirrel (Sciurus carolinensis), is not a native British Columbian. It was introduced in Vancouver's Stanley Park, and has spread throughout the city. More recently, the species has spread across southern Vancouver Island, following its release about twenty -five years before. It is larger than the Red or Douglas Squirrels, and occurs in gray or black forms. This species does not defend a territory, going pretty much where it pleases. The native squirrels expend considerable energy "defending" their territories from the perceived interloper, a habit that probably reduces their success.
Gray Squirrels normally nest in tree cavities, but in summer may use leaf nests called dreys, which are skillfully constructed on a platform of branches. They are opportunistic omnivores, eating vegetable food most of the time. They are said to eat the eggs and young of birds, but there is some doubt as to whether they do more harm in this way than the native Red Squirrel. Like many introduced species, though, they seem to be at their worst where human activity has made life easier for them.

While these three species are all active by day, there is a squirrel which ventures out only after dark. What's more, it is equipped to move from place to place through the air. This is the Northern Flying Squirrel (Glaucomys sabrinus). These animals do not fly as bats do; they are really only gliders, staying aloft on folds of skin, which stretch between their front and back legs. They are almost as widely distributed in Canada as the Red Squirrel, but are much less often seen. They are small, weighing only about 160 grams. This species is the main prey item of the threatened Northern Spotted Owl, and it is interesting to note that neither species occurs on Vancouver Island.

Flying Squirrels eat mainly fungi in summer and fall. They play an important role in transporting the spores of some mycorrhizal fungi that are critical partners in a healthy forest ecosystem. They are dependant on mature forests to provide cavities in snags for their dens, and for the associated fungi and lichens that sustain them.

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