In Great Britain, Ireland, and in Italy numbers have decreased drastically in recent years.
This decline is associated with the introduction by humans of the eastern grey squirrel (Sciurus carolinensis) from North America.
The coat of the red squirrel varies in colour with time of year and location. There are several different coat colour morphs ranging from black to red.
Red coats are most common in Great Britain; in other parts of Europe and Asia different coat colours co-exist within populations, much like hair colour in some human populations.
The underside of the squirrel is always white-cream in colour.
The red squirrel sheds its coat twice a year, switching from a thinner summer coat to a thicker,
darker winter coat with noticeably larger ear-tufts (a prominent distinguishing feature of this species) between August and November.
A lighter, redder overall coat colour, along with the ear-tufts (in adults) and smaller size, distinguish the Eurasian red squirrel from the American eastern grey squirrel.
However, the population in Scotland is stabilising due to conservation efforts, awareness and the increasing population of the pine marten, a European predator that selectively controls grey squirrels.