The red squirrel or Eurasian red squirrel (Sciurus vulgaris) is a species of tree squirrel in the genus Sciurus common throughout Europe and Asia. The red squirrel is an arboreal, primarily herbivorous rodent.
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. 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.
The red squirrel has a typical head-and-body length of 19 to 23 cm (7+1⁄2 to 9 in), a tail length of 15 to 20 cm (6 to 8 in), and a mass of 250 to 340 g (9 to 12 oz). Males and females are the same size. The Eurasian red squirrel is somewhat smaller than the American eastern grey squirrel, which has a head-and-body length of 25 to 30 cm (10 to 12 in) and weighs between 400 and 800 g (14 oz and 1 lb 12 oz).
The long tail helps the squirrel to balance and steer when jumping from tree to tree and running along branches and may keep the animal warm during sleep.
The red squirrel, like most tree squirrels, has sharp curved claws to help it to climb and descend broad tree trunks, thin branches, and even house walls. Its strong hind legs let it leap gaps between trees. The red squirrel also can swim.
The coat of the red squirrel varies in colour with time of year and location. There are several 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 coexist 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 red squirrel from the eastern grey squirrel. The red colour offers camouflage when seen against the bark of pine trees.
Red squirrels occupy boreal, coniferous woods in northern Europe and Siberia, preferring Scots pine, Norway spruce and Siberian pine. In western and southern Europe they are found in broad-leaved woods where the mixture of tree and shrub species provides a better year-round source of food. In most of the British Isles and in Italy, broad-leaved woodlands are now less suitable due to the better competitive feeding strategy of introduced grey squirrels.
The red squirrel is found in both coniferous forest and temperate broadleaf woodlands. The squirrel makes a drey (nest) out of twigs in a branch-fork, forming a domed structure about 25 to 30 cm in diameter. This is lined with moss, leaves, grass and bark. Tree hollows and woodpecker holes are also used. The red squirrel is a solitary animal and is shy and reluctant to share food with others. However, outside the breeding season and particularly in winter, several red squirrels may share a drey to keep warm. Social organization is based on dominance hierarchies within and between sexes; although males are not necessarily dominant to females, the dominant animals tend to be larger and older than subordinate animals, and dominant males tend to have larger home ranges than subordinate males or females.
The red squirrel eats mostly the seeds of trees, neatly stripping conifer cones to get at the seeds within, fungi, nuts (especially hazelnuts but also beech, chestnuts and acorns), berries, vegetables, garden flowers, tree sap and young shoots. More rarely, red squirrels may also eat bird eggs or nestlings. A Swedish study shows that out of 600 stomach contents of red squirrels examined, only 4 contained remnants of birds or eggs.
Excess food is put into caches called "middens", either buried or in nooks or holes in trees, and eaten when food is scarce. Although the red squirrel remembers where it created caches at a better-than-chance level, its spatial memory is substantially less accurate and durable than that of grey squirrels. Between 60% and 80% of its active period may be spent foraging and feeding. The active period for the red squirrel is in the morning and in the late afternoon and evening. It often rests in its nest in the middle of the day, avoiding the heat and the high visibility to birds of prey that are dangers during these hours. During the winter, this mid-day rest is often much briefer, or absent entirely, although harsh weather may cause the animal to stay in its nest for days at a time.
No territories are claimed between the red squirrels, and the feeding areas of individuals overlap considerably.
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