Biology Reference
In-Depth Information
Northern flying squirrel
Just how far can a flying squirrel glide in terms of horizontal distance? There's no absolute answer
to this question because there are so many variables. These include the height from which the squirrel
launched; the slope of the land, if any; and wind velocity and direction. Height is the most important of
these, because the glide ratio of a flying squirrel is about three feet horizontally for each foot of height.
Our North American flying squirrels can certainly glide two hundred feet or more, and some author-
ities say as much as three hundred feet. Considering the glide ratio, that would mean launching from a
height of one hundred feet—certainly possible in many situations, although most glides are a good deal
shorter. In theory, at least, the only limit to a flying squirrel's length of glide is the height from which it
started.
Because a flying squirrel in a long glide acquires a certain amount of velocity, one might think that
the little animal would injure itself by crashing into its landing site on the trunk of a tree. But in fact this
presents no problem for the squirrel, which, as it prepares to land, drops its tail and raises its forepaws,
thus creating wind resistance much as an airplane does when it lowers its flaps during a landing. The
squirrel, now almost in a vertical position, lands lightly against the target tree and promptly scurries off
about its business.
Nor is a soft landing the only talent that flying squirrels exhibit while gliding. By using its tail as its
main rudder, and also by moving its legs, thereby tightening or loosening the flaps of skin on one side
or the other, the flying squirrel can maneuver well enough to avoid branches and other obstacles during
a glide. In fact, a flying squirrel has been observed banking through an arc of as much as 180 degrees
during a glide.
It's widely assumed that flying squirrels are almost entirely nocturnal, but twice I've seen the little
creatures abroad in daylight. One afternoon, while it was still full daylight, I saw a flying squirrel glide
from a large maple tree to a tall balsam fir on the edge of our woods. The squirrel landed a few feet
above the ground, scampered up the trunk, and, to my surprise, disappeared into a small hole that I
hadn't previously noticed. Though I watched for some time, the squirrel failed to reappear; almost cer-
