Tree squirrels are the members of the squirrel family (Sciuridae)
commonly just referred to as "squirrels". They include over a hundred
arboreal species native to all continents except Antarctica and
Australia. They do not form a single natural, or
monophyletic group; they are related to others in the squirrel family,
including ground squirrels, flying squirrels, marmots, and chipmunks.
The defining characteristic used to determine which species of
Sciuridae are tree squirrels is dependent on their habitat rather than
their physiology. Tree squirrels live mostly among trees, as opposed
to those that live in burrows in the ground or among rocks. An
exception is the flying squirrel that also makes its home in trees,
but has a physiological distinction separating it from its tree
squirrel cousins: special flaps of skin called patagia, acting as
glider wings, which allows gliding flight.
Sciurus carolinensis, common name eastern gray squirrel or grey
squirrel depending on region, is a tree squirrel in the genus Sciurus.
It is native to eastern North America, where it is the most prodigious
and ecologically essential natural forest regenerator.
Albino and white squirrels
One of the ways that squirrels impact human society is inspired by
the fascination that people seem to have over local populations of
white squirrels (often misidentified as being albino). This
manifests itself by the creation of social group communities that form
from a commonly shared interest in these rare animals. Other impacts
on human society inspired by white squirrels include the creation of
organizations that seek to protect them from human predation, and the
use of the white squirrel image as a cultural icon.
Although these squirrels are commonly referred to as "albinos",
most of them are likely non-albino squirrels that exhibit a rare white
fur coloration known as leucism that is as a result of a recessive
gene found within certain Eastern gray squirrel (Sciurus carolinensis)
populations, and so technically they ought to be referred to as white
squirrels, instead of albino.